The great misfire mystery

Yo everyone!

I haven't posted to this board for a while, but as I was reading I found a message from a few days ago regarding misfires. Hopefully the following information I will provide will help some of you, as I was battling this problem for 2 years.

First of all, I have a 97 Firebird, 3.8 V-6 automatic with 86,000 miles. My misfire problems started as early as 36,000 miles when the dealer replaced the stock plug wires. Since then, I've replaced wires 2 additional times, plugs 5x, all 3 coils, ignition module, and the camshaft position sensor. And you know what? Misfires kept coming back.

The problem causing these pesky misfires? Engine heat. Our 3.8 V-6s are nestled underneath the dash somewhat, so ventilation isn't very good, especially on the passenger's side of the engine. I finally kicked this problem when I found my #6 MSD Spark plug wire boot cracked and cooked a bit from the heat when the wires weren't even that old. Now these are expensive wires, so the stock ones will burn even easier. Make no mistake, the excessive heat will destroy the wires prematurely, which is why GM was replacing them in the first place.

All 6 of my MSD wires tested fine with an ohm meter--just the boot was cracked on #6. Here's what I did to fix the problem:
1) Replaced all 6 plugs.
2) Carefully removed 4 of the 6 wire boots from the #4, 6, 1, & 3 wires.
3) Installed spark plug wire sheathing that I bought from Napa AutoParts on the #4, 6, 1, & 3 wires--from the boot end until it meets the wire looms on each side of the engine.
4) Reinstalled new boots on these 4 wires.
5) Installed Protect-A-Boot Spark plug wire boot protecters from Design Engineering (at Checker Auto Parts--see www.cskauto.com) on all 6 spark plug wire boots.
6) Reinstalled the wires.
7) Installed new #6 nylon wire looms. I believe the ones I got are from Made For You. Their wire looms won't melt or disform. I bought the 8mm looms and drilled them out slightly to fit the larger wires.

Since the #4, 6, 1, & 3 wires are nested under the manifolds, they get the hottest. The excessive heat will destroy the wires prematurely--worse if the wires are stock ones. With the boot protecters and heat sheathing, the wires and boots will be protected from this heat and last much longer. Note that the boot is fully protected using Design Engineer's boot protectors.

By the way, my car did not come with the metal boot protectors that some cars came with. But I heard from some that the boots sometimes will arch on these.

Well I hope this helps someone avoid the hassles I had trying to solve the misfire mystery.

Man!!! That's the greatest description of how to eliminate our "mystery" misfire problem. Is there some way this post can be added to the board so everyone with this problem can just reveiw what gig said? Much props to you for taking the time to type that all down. I'm sure many of us can benifit from what you posted....Thanks a million!!!:bow:

Good looking out bro. :)

I used to live in Waipahu but moved out here almost five years ago.

I've changed my plugs twice in 12 months! I was beginning to think there was a problem with my car. Thanx for the help!

I remember when he posted this on the "other" board almost a year ago (WOW!!!! time flys like a mothah) when i posted about my trouble replacing the plugs/wires then.

way to dig up a thread. :rolleyes:

heh, just kidding. ;)

does anyone know if the misfire problem is pretty common on newer tubular manifolded 3.8Ls?

thank you :)

Hey dudes!

I'm back for a post! Just to let you all know, my solution to the misfire mystery is time proven up to 17,000+ miles! Without adding the sheathing and boot protectors, after changing plugs I would get misfires at 7,000mi for double plat plugs (Autolite double plat plugs) and 10,000 for racing plugs (Autolite racing plugs). So looks like my solutions works. By the way, I also adding the Napa sheathing from the coil to the wire looms too. This fully protects the wires from the heat.

I just bought some AC Delco 41-101 plugs for my car, and will be installing them in a few weeks. From what I've read, these plugs and the Rapid Fire 14 are what GM recommends for our cars/3.8 engine. It's a real pain to change plugs (I put 15,000mi/yr, so with the Autolite AR103 racing plugs I'm currently using I would have to change every year), so with these I figure I can run them for at least 70,000mi or more. On the box the warranty is 100,000 miles. Anyone use these?

Originally posted by MustangEater82
does anyone know if the misfire problem is pretty common on newer tubular manifolded 3.8Ls?

thank you :)

gett headers only take you about 20-30 mins to change the plugs, and can be done from the top of the car.

my friend and i both have 2000 f-bodies with the 3800, we both got this prob at the same time almost within the hr, kinda odd, but he got new plugs ans fuel filter and it calmed down, mine did too just i didnt do anything, now they are acting up a lil. so the heat issue makes alot of sense.

thanks alot

Originally posted by viper03af
gett headers only take you about 20-30 mins to change the plugs, and can be done from the top of the car.


ehhh not in the mood to spend liek $500 for a 3 hp gain...

I have tubular manifolds I am sticking with them...

I woudl rather spend the extra half hour changing the plugs then an extra 12 hours installing the headers :)

Originally posted by 00SilverStar
my friend and i both have 2000 f-bodies with the 3800, we both got this prob at the same time almost within the hr, kinda odd, but he got new plugs ans fuel filter and it calmed down, mine did too just i didnt do anything, now they are acting up a lil. so the heat issue makes alot of sense.

thanks alot

500$$$$ summit has pace setter for lik $289:eek:

I was just about to post a new thead about my sons 99 3800 Camaro (51,000 miles), when I read this one. The problem that he is having is, while in second gear (it's a 5-speed), the car starts to "buck". It feels like it's missing but I am not sure. It may also do it in other gears but it seems most noticable going through second. Does this sound like the poroblem that was discussed or something else?

Thanks
Joe:D

sounds like it to me, thats how mine started out. i got the taylor 8mm wires from thunderracing and and new plugs, car runs like new now.

and you can do plugs from the top on factory headers., just it took me from 9am to almost 1pm before i was done, and i have some cuts on my hand now.

Hey all--

Regarding this misfire problem--I recommend using good spark plug wires, like MSD. So far, I have 50,000 miles on my wires, and they still work like new. I have heard some problems with Taylor and Accel wires, which is why I have stayed away from using them. Note that using the heat sheathing on the wires and boots will make them last a lot longer, and insure your misfire blues are gone.

Thanks

I just put convoluted tubing on mine to keep them from touching the manifold, but will go get some heat sheathing for ALL of my plugs. Did'nt know it had that much to do with the V6 misfires

Sweet! This info is way useful. I seem to have misfire problems every so often. Like many of us, I've changed plugs and wires numerous times. One question though, of anyone whose had this problem, did your "Service Engine Soon" light come on? Mine will seem to come on, stay on for a few days and then eventually go off. While the light is on, my car runs kind of crappy. As soon as it goes off, it'll run fine. I can always tell when my light is about to come on because I'll start to feel a light "misfire" tugging while driving. Also, when my car switches from 1st to 2nd gear, it'll jerk. I do know that something as simple as running a different octain than normal or even adding an injector cleaner to a fill up will bring this on. From what I understand, the computer needs to "sync up" with what's going on with the engine and will eventually correct itself. However, if I've done none of these things and this happens, I've always assumed that it was an ignition problem. In your experiences, once this starts, is it constant or does the misfire only seem to happen after the car has been on and warmed up? That's when it seems to happen to me the most. One note about my experience, this is not a constant thing with my car. It only seems to happen every so often. I've almost become immune to my "Service Engine Soon" light.

Originally posted by MacPHYST
Sweet! This info is way useful. I seem to have misfire problems every so often. Like many of us, I've changed plugs and wires numerous times. One question though, of anyone whose had this problem, did your "Service Engine Soon" light come on? Mine will seem to come on, stay on for a few days and then eventually go off. While the light is on, my car runs kind of crappy. As soon as it goes off, it'll run fine. I can always tell when my light is about to come on because I'll start to feel a light "misfire" tugging while driving. Also, when my car switches from 1st to 2nd gear, it'll jerk. I do know that something as simple as running a different octain than normal or even adding an injector cleaner to a fill up will bring this on. From what I understand, the computer needs to "sync up" with what's going on with the engine and will eventually correct itself. However, if I've done none of these things and this happens, I've always assumed that it was an ignition problem. In your experiences, once this starts, is it constant or does the misfire only seem to happen after the car has been on and warmed up? That's when it seems to happen to me the most. One note about my experience, this is not a constant thing with my car. It only seems to happen every so often. I've almost become immune to my "Service Engine Soon" light.


Man mine does the exact same thing!!!! Feels like i gotta shift kit when it goes to second lol. My ses light also goes on and off when it feels like it. So I guess engine heat is the main problem, this is one of those posts everybody should read.

Just finished the mod and the car is running great. Thanks for the info.

Well, mine is going in the shop tomorrow. Not looking forward to seeing the bill from the Pontiac dealership. However, my wires are under warranty so maybe that'll help a little. I've tallked to the shop forman earlier and spoke of the heat shielding, routing, etc. He mentioned that he'll look into what can be done and that we'll chat about it in the morning when I drop it off. Hope they can fix it right away. Can't go too long without a car. :(

Well guys... I did my plugs and wires today.

I have a 2000 with tubular manifolds so I assume it was a little easier for me. My car is pretty stock with 38,200 miles on it.

I used
-8.5mm Msd wires (from www.ammperformance.com $50)
-NGK TR-55 Plugs (from www.mascperfomance.com)
-MSD 1000* heat sheating 6' roll (from Summitracing.com Part # MSD3412)


When I pulled looked at my old wires the # 6 wire was actually laying on my exhaust manifold, when I pulled it off, it was burnt in 2 spots, and and the boot crumbled apart, it also looked burned up at the tip of the plug. Also the number 2 wire had rubbed agianst something and worn through the outer coating, and the #4 wire looked burned up at the plug.


I cutt the 6' roll of heat sleeving in 1 foot sections(giving me 1 foot for each wire) I then with a utility knife shaved off the MSD logo off the spark boot, just enough to cut it off not dig into the boot. I then put the heat sleeves on eave wire, zipp tied it at the end and used electrical tape to make it look a little nicer.

I resued the old metal boot shields that were factory on the car, I twisted them over my new plugs with heat sleeves on them.

Then I startd doing the plugs on the car(I uesed a handy tool, its like a socket wrench with but doesn't have a handle, just a circular disc that ratchets. I used the a regular wrench to start the bolt and the new tool to finish) IT was pretty easy. I picked the tool up at advacned auto for $8, its worth it, a regualr wrench woudl have take forever since you coudl probably only turn it one click in most spots. I then installed my newly gapped plugs at .045 to finger tight with the new tool.

then I installed each plug boot, they offered mor then enough protection in my opinion, I ran the passenger side wires straight up and over the motor instead of behind the alternator when they were factory installed.


First impression, car ran alot better and smoother, I plan on taking it to the track and seeing the difference. My stock wires were not doing so well.


In my opinoin if you are going to do plugs and wires, take a little more tiem and do it right...

Mine blew out for the second time within 2000 miles :mad: Last time it was my #6. Just yesterday It happened when leaving work, let me tell ya it's really fun trying to drive in traffic up a mountain when your cars popping and wont go :rolleyes:

I'm going to Copy this and show it to my mechanic monday, the car never even made it home this time I had to ditch it 1/2 way (was able to roll to my mechanics)

Whats the difference between sheathing? Wire looms? and boot protectors?

thanks gig:cool:

Great info... typical that I find this just before I'm doing an LT1 swap, and after I've canged my plugs/wires 3 times and had my car into GM 3 times :rolleyes:

Regarding the service engine soon light, I was having this problem prior to changing my plugs and wires. I did get cheap wires and the bosch +4 plugs. RUNS MUCH BETTER. The light kept saying misfire cylinder 1. I usually got this to come on by giving the car alot of gas trying to get onto the interstate with a short on ramp. I have not been able to trip the light since I changed the plugs two weeks ago. I was told by three different chevy dealerships three different things. Dirty injectors, carbon build up messing with the EGR valve, and bad wires. Well the bad wires appears to have been the issue.

yes the bad wires are 90% of the cause

Shouldn't GM know about this then? My bro took his car to a pontiac dealer about that and i don't think they said anything bout what it could be, they just said that it was misfiring but no SES light was on. Thanks for this sticky, hope it solves his problem. Funny thing is i just made another post about something he bought when he was trying to fix it.

So it is always the wires?, never plugs or coil packs?

I never even knew that they had that problem. *knock on wood* Mine has 150K on it and has never had that problem. It surprises me because my car has had several problems since I got it (it had 80K on it).

Had the SAME problem as everyone...
'97 Camaro RS 3.8L 3800II engine
started getting the bucking/misfiring, then it got worse, went away, got worse. Took it to the chevy dealer and they replaced the fuel injector, it got better for a couple days then stedily got worse. Changed out the coil packs, was good for a few days, then got worse again. I'm ordering the DEI protect-a-boot packs and installing them w/ borsch platinum 2 plugs and new plug wires...will let you know how things work out!!! Thanks to everyone for finnally fixing this crazy problem!
:bow: :bow: :bow: :bow: :bow: :bow: :bow: :D

OMG!!!! passenger's side, farthest back plug wire...fell apart IN MY HAND!!! this heat thing is really a pain in my :mad: !!!!!!!! ANY way got the new plugs and plug wires in....RUNS LIKE A CHAMP!!!
already have a new fuel injector and just changed the oil!

Waiting for the DEI protect-a-boot covers to come in...WILL def. let you know if this solves the great misfire mystery!!!!!!!!

Be carefull with this!

I purchased a 97 Camaro(v6) with 97,000 on it and it displayed a simmilar problem with #3 misfire code.

At 105,000, I am looking for another motor to replace the one with the #3 piston rod sticking out of the side of the block.

Good luck!

Hey everyone-

-99 3.8L Camaro 80,000 miles with the same missfire type problems as described in this thread. About six months of back and forth to the shop (tune ups, filter changes, plugs & wires) the problem slowly would come back. Finally my mechanic decided to heat the engine to driving temp. and then we discovers the coil packs were only producing 40-50% less than they should once engine temp was up. Replaced coil packs and problem has not returned in 8 months (knock on wood).
Hope this helps some people :)

It seems to be a heat problem w/ not just one component. Plug wires seem to go first and the shops just tell us it's the fuel injector/filter...but it's not. Then the wires just worse, specially the back passenger's side wire, while the coil packs start suffering.

here's what fixed my problem:
DEI protect a boot <- very important!!!
new plugs N wires w/ high heat sheathing
New ignition coil packs
new fuel injector/filter <000 dunno if that helped anything but the guys at chevrolet thought that was the problem so i suppose it didn't help anything ;)

and now she runs like a champ!! Just turned 100K and goes like it just rolled off the assembly.

My '96 has had very similar symptoms so I am extremely glad to have found this thread. I have been having intermittent misfire problems with #5 - can anyone tell me which cylinder is #5, or point me to an image with a cylinder map for the '98 3800 engine?

Many thanks!

This month I had another engine put in my '96 Camaro, a 3.8 from a '97 with 50,000 miles on it. The lovely valve in the heater hose busted causing a head gasket to blow in the original engine. Great. I had this great idea to, instead of getting it repaired for $1700, get another engine put in it for $2100. My old engine had 132,000 miles on it anyways. Seemed smarter to spend a little more on a different engine with a 2yr warranty. So, all went well until they started up my car with the replacement engine. SES light flashing. Found a misfire on #4. Replaced the coils from one engine to the other. The light turned off. I drove my car 30 miles home from the mechanics, excited to have my car back after a month of thumbing it.

Unfortunately, I've had a misfire problem... again. I bought new coils, still misfires. I replaced the plugs and wires, still misfires. Same #4 cylinder. Could it be a fuel injector? I ran some fuel injector cleaner through a couple tanks of gas, really isn't any better.

It's manual and it misfires on the lower half of the gears. It runs smooth until it warms up, then the jerking starts. I can make it miss less, but I'm a little ticked that $2500 later, it still runs badly. Any ideas? I'm hoping it's something easily fixable.

Thanks,
Chris

PS - As far as the cylinders, the wires coil side, top to bottom or back to front are 1,4,5,2,3,6(most easily accessible). One at a time will help link them with the corresponding plug. Or 2,4,6 on passenger and 1,3,5 on driver.

http://www.turbov6camaro.com/images/wires.JPG

hope this helps

I have a 3.8L '97 Camaro and from what I have learned that there was a recall on the spark plug wires from way back when:

Campaign - Spark Plug Wires/Driveability Complaints
Number: 99057
Date: 11/01/99
Campaign - Spark Plug Wires/Driveability Complaints
Special Policy 99057 - Spark Plug Wire
Replacement # 99057

99057 -- Special Policy Adjustment -- Spark Plug Wire Replacement

1995-1998 Chevrolet Camaro and Pontiac Firebird Model Vehicles

Equipped with 3.8L Engine (RPO L36, VIN Code K)

Condition

Some owners of 1995, 1996, 1997 and 1998 model year Chevrolet Camaro and Pontiac Firebird vehicle equipped with 3.8L engine (RPO L36, VIN Code K) may experience driveability complaints such as rough idle, misfire and/or illumination of the Malfunction Indictor Lamp (MIL) (code P03-X-misfire). These conditions may be due to cracked spark plug boots, connector terminal corrosion or unseated terminals.


I didn t have problems with mine until around the 50k mileage mark and didnt know about the recall. I just replaced the sparkplug wires and it ran like a champ since then; up until now.

I am now getting a misfire in my #1. I had to replace the rear main oil seal this weekend so I had the opportunity to replace all my spark plugs(originals,134k mileage) in the process with Bosch Iridium plugs and the wires again. But I still have the misfire in #1. So I am about to go out and replace the coils to see if that will help. Just wanted people to know about the recall Chevy had with the plug wires.

Well I replaced my ignition coil for the #1 cyclinder and it didnt help. So now I am stuck.

Any suggestions (replaced sparkplugs, sparkplug wires and ignition coil)

My Camaro has had the same problem. I didn't think it was as bad as the other cases I've read, so I just changed the spark wires, and it seems to have fixed the problem.

Maybe I'm a newb for asking, but does this misfire affect 3.4L engines also?

Maybe I'm a newb for asking, but does this misfire affect 3.4L engines also?

It shouldn't.

but 3.4Ls will can have misfires, make a thread about it I am sure we coudl figure out your problems.

I'm looking at buying a 2002 Camaro V6 with the 3.8. Was this problem cleared up by the final year of production?

*UPDATE*

If you read up there you say I did the heat sheathing and msd wires and plugs.

at 38,200 miles


My car now has 52,000 miles
I was getting some knock and other things since I can log know with hptuners, I was suggest to try a colder range of plugs(autolite 605s, and it didn't fix my knock problem.

So last night I pulled my plugs, just to see, and figure couldn't hurt to swap plugs before race season(too hot in summer in FL)

and my plug boots were 100% fine, plugs looked good, and wires looked good from what I can see. Its only been 14,000 miles but they looked great and nearly brand new, not even dirty(well at the boots).

Car runs fine, no misfires detected with hptuners before or after.



not sure if it affects it but my car had been 100% outdoor car in FL, so its been exposed to more then the average heat.

I'm looking at buying a 2002 Camaro V6 with the 3.8. Was this problem cleared up by the final year of production?


for the most part 99+ cars didn't have nearly the problem since they switched to tubular manifolds but it was still somewhat present. But, its an easy fix regardless. This would not be a reason to keep my from buying a car by far.

for the most part 99+ cars didn't have nearly the problem since they switched to tubular manifolds but it was still somewhat present. But, its an easy fix regardless. This would not be a reason to keep my from buying a car by far.

Good thing. Three years old, 20K miles, near-perfect condition (smoked in :cry: according to the ashtray residue, but dealers have been trading it around trying to sell it in an SUV marketplace).

:p

Thanks!

whats the firing order for a v6 2.8l camaro. 1988

my '98 was having misfire problems. rough idle, horrible mileage. took it to the shop and they said my injectors were sticking. they put some "cleaner" crap through the gas tank and it did nothing. so i took it back and told them to actually clean the injectors themselves. took them two times but no more misfire.

My 99 Firebird has the old cast manifolds. I may start to look for a set of tubular manifolds. I had a good running car until I found out my coil packs screws had loosened over time, after I tightened them, I had all kinds of power now the contact touched well and the misfire went away.-Tim

Hey Gig. I was having the same problem after making a tune up to my car.
Wires, Plugs, filters were changed You know, the usual.
The misfire occured, then the coils were changed too and the problem was still there.
Untill I joind this page and found out what You suggested, I found a cooked wire on cylinder 6.
So after replacing it the car runs much better.

Thanks for the advice.

Daniel Chairez
Tijuana Mexico.

my 98 3.8 had a po420 and p0300 and it would miss whenever i got on it. i changed the plugs, fuel filter, and even went as far as changing the cattalyc converter( which got rid of my p0420) the p300 has not returned but still misses whenever i get on it real hard. when i changed my plugs i saw the wires looked like they were in flawless condition. does this sound like the problem. i guess ill change the wires today.

well changed the wires and nothing changed but while i had everything apart i did resistance checks on my ignition coils and found that the middle ignintion coil was completly open no continuity at all. changed that ignition coil and now it runs like a champ!!!

it read 0 ohms of resistance? I checked the primary and secondary terminals of all my coils... they all read good (low resistance)

I've changed wires, plugs, sparks, coils, ICM still getting p0300 "General Misfire" so I'm thinking its clogged injectors?

I've changed wires, plugs, sparks, coils, ICM still getting p0300 "General Misfire" so I'm thinking its clogged injectors?check the fuel lifter, accualy replace if it hasn't been done its only 11 bucks and take about 15-30 minutes to change......

then if that dont help look into the injecotors and fuel pump

yes, its a new fuel filter
so its either clogged injectors or bad fuel pump @ 38k miles

I wonder if changing my "Injector Flow Rate vs KPA" to 21.99 lbs across the board would cause this misfire?

yes, its a new fuel filter
so its either clogged injectors or bad fuel pump @ 38k miles

I wonder if changing my "Injector Flow Rate vs KPA" to 21.99 lbs across the board would cause this misfire?
chang e it back and see what it does

i changed it back to stock so it definately isnt the tune.
its obviously clogged injectors @ 38k miles
I'm going to do a seafoaming, maybe rip the suckers off
and put them in a cleaning agent-solution, then hook each of them
up to a 12v dc
battery(to open it up and let the cleaning agent in)

think I can just do a fuel pressure check to see if the fuel pump is giving enough pressure? duh Obviously
Its just weird that the fuel pump would act up (showing signs that its going out) without completely going dead.

Hello,
I have a p3### misfire code for the number 3 cyl. on a 96 camaro 3800 the SES light is on and blinks, i know this means i can damage the cat so i need help asap.

I changed plugs,wires,coils ECT to no avail my gap is set right and wires are clear of manafold. i am at a loss. the car runs verry ritch, i can smell raw gas coming from the exhaust. so im guessing the fuel filter/pump is ok. it also has starting problems, sometimes takes 3 tries to start. I want to fix this ASAP as i just bought the car and would like it to run right.

Also after changed all the parts the miss got dramaticly better but its still there, i dumped some injector cleaner in it and its helped some but not alot.

PLEASE HELP!!

Don

i heard its also bad to run on a constant misfire.
what about seafoam in the gas tank, couldnt hurt?
cylinder 3 is p0303
have you changed the ICM recently?
When cars run lean misfires show up alot more.
I would think that running rich would cover it up?

what kind of damage can be caused if the misfire is left untreated

ICM? sorry man but could you plz tell me what that is the ICM is ?? Ignition Control Mod? if its under the coilpacks it tests out ok via autozone.

I did a compresion check and i have 180# on number 3 . I did have a cloged cat tho, the prev owner let the wires ground out on manafolds and let raw gas into the cat. i have a pipe in there now and i have alot more power now but still have the number 3 missfire, im also worried abought the o2 sensor behind the cat. i heard i can buy a o2 mask for it.

meanwile i still have the damn missfire. p0303 cyl #3 missfire not the p0300 random missfire. im thinkin cloged injector? plz advice guys. at 2,000 rpm it goes away, and its getting spark?!?

Thx Don

p.s. Wish u could of seen what came out of the cat, balls of melted crap, and see the diffrence in power! i owned a 3800 firebird and i know it would spin the tries off the line, and well with a miss, that isnt gonna happen and thx for the replys

Ignition Control Module, yes, it sits under the coils.
the coils connect with the ICM.
the o2 mask = o2 simulator (it tricks the computer into thinking the o2 is fine) Or you can get computer tuning to remove it
180 psi sounds barely low, might have a head gasket leak?
I did, but mine was at 90psi at the lowest

I am still getting my p0300 general misfire code. I've checked everything!!
The only thing I have left to do is get my Air-to-Fuel Ratio % back to a decent amount (through tuning)
Its running pretty lean and that'll make a misfire show up more...
Im sorry I cant help!!

oh yeah, I did a compression check #1 cylinder was at like 180psi, then i took it to a shop and they told me it was only 90psi!!!!!
so I brought it back home, did a compression check it was at 180psi again!
FREAKING WEIRD!!!
I took it apart and you can totally tell I had a coolant leak because the #1 cylinder is all clean as shiny. The other cylinders are black

Ignition Control Module, yes, it sits under the coils.
the coils connect with the ICM.
the o2 mask = o2 simulator (it tricks the computer into thinking the o2 is fine) Or you can get computer tuning to remove it
180 psi sounds barely low, might have a head gasket leak?
I did, but mine was at 90psi at the lowest

I am still getting my p0300 general misfire code. I've checked everything!!
The only thing I have left to do is get my Air-to-Fuel Ratio % back to a decent amount (through tuning)
Its running pretty lean and that'll make a misfire show up more...
Im sorry I cant help!!

Computer tuning? my friend had a snapon obd2 scanner/programmer can it be done with that? if so couls you explain how?

Thx
Don.

i dont know much about the snap on? does it really program?
I would think it could only read/scan?

Ok Here Is THat Latest,

After a new computer she stoped missing ALOT now it only misses under hard acceleration, so now i got to figure out what that is

i changed my spark plug wires and my ignition coil(s) but my car is still jumping between 1 & 2 gears from after having the engine on for a while. why is it doing that still?

I had the same misfire problem. Because I didn't fix it soon enough, the catalytic converter also went bad because of bad spark plugs, so what i'm saying is not to wait.

Anyways, this is what I did to fix the misfire:

First is a tune up, change the spark plugs, spark plug wires and fuel filter. Don't buy stock parts, invest in some good plugs and wires (MSD). It ran better but still misfired. I bought some heat resistant wire sleeves and boot protectors, but my mechanic advised me to return them because they are junk. So the next step was the ignition coil pack. That was replaced and it ran like a champ, mifire was solved 100%...up until the engine blew because of a bad oil change at Valvoline...bastards. >:0

But if you did all that and it still is misfiring, I believe the fuel injectors are the last thing needing to be replaced.

This is the best read I have found for the P0300 code - it also explains ALL the other items (some pretty simple) that have been overlooked in chasing this problem

http://www.aa1car.com/p0300

Hey I have a 1991 3.1 Camaro with 281300 miles on it this misfire problem is it the same on these as the 3.8 or does anyone know? Also is there much difference in the 5.0 engine and the 5.7 stock engine? When this 3.1 blows I am wanting to switch out everything and take out the computer but if the 5.7 or 5.0 is good enough I will not have to. Any suggestions.

I had the same problem with my 99 3800. Last year my throttle body sensors went bad and since they are mounted in the trottle body I had to replace the entire assembly for a lot of $$$. :mad:


Recently it had been hard to start when the engine is up to temp and it idles rough and sometimes shuts off at idle. No problems when up to speed though.

Today, it got a lot worse and I scaned a P0300 (ramdom misfire). It turns out that the middle coil pack connections were corroded. Unbolt them and cleaned the terminals with a wire brush. It is running good now.

Glad to find a solution to a problem that didn't cost me an arm and a leg!

Hey guys, i dug this thread up, is there a writeup somewhere that is really detailed to help me fix my misfire problem. Car just went over 80k miles (1998) model.

I have plugs and plug wires to do, so any help is greatly appreciated...thanks...

Here is a thread i made just a little while back about the problems ive been having, i have the car stored right now, with the problem NOT fixed.

Alright, for like 300-400 miles now, every so often my car bogs down really bad. I recently put a walbro intank in it, about 1000 miles ago. The first time it happend (about 400 miles ago) the ses light started blinking, and the car seemed like it was running only 3 cylinders or something. It made a funny sound like a car with a huge cam at idle or something. The first time was around like 10-20 mph. So i didnt think too much about it. The ses light went out the next time i was in the car. A few days later I was cruising like 60mph, and all the sudden it bogged for a few seconds and came back??? light and all and went away? It seems like it happends at least once a week and maybe twice.??

Before you ask, I havent used my nitrous for a long time, because i wanted to change the pump first. So I havent sprayed in prolly 2000 miles. I changed the plugs too, thinking that might help, but didnt. Im too scared to fun my nitrous becaues i dont want anything bad to happen.

Its got almost 110,000 miles on it now, and has ran good ever since i got it with 86000 on it.

UPDATE****

Since then, i got a new magnaflow cat on it, new TR6 plugs, and some seafoam ran through it. Fuel Filter isnt too old either, and a new walbro has been installed too

Im going to try the wrapping/new plug wires cause they prolly have 20,000 miles on them, and checking out the ICM???? Anything else---coil packs??

Ill keep you updated

hmmmm My problem sounds a little different then anyone elses....

When I first start my car and its cold (idleing) it runs fine, but then when it warms up a little bit (rpms are now at 1000) About every 10 seconds it will sound like its misfiring from the exhaust. It will break up. Now when i drive, anything under about 3000rpms and under 1/2 throttle it will run completly normal with no stutters or anything....but once i get about half throttle or more and over 3k it will pull then break up really bad (like someone just turned the power off) then it will pull again and keep doing it...basically it jerks in and out of power. Now, i am turbocharged and i dont have a cat so a bad cat is out of the question. I Replaced all of my spark plugs, changed my stock plug wires to MSD high currency ones, put a new fuel filter on and took out my injectors and inspected them/cleaned them. I have a inline MSD high pressure fuel pump and thats still working 100% (if you know anything about them, their so loud you can hear them working) But my intake fuel pump could also be bad. The car is in winter storage for right now and i didnt do a fuel pressure check yet however, It still has the stock coil packs (which have 102K on them...they were never changed when i had my new motor put in which currently has 26K on the clock)...So im gonna buy some AC delco performance coil packs and change those out....Im pretty sure thats the problem but not 100% positive...

also, Before i changed out the wires,plugs etc. i thought maybe i was running too lean with the turbo so i took off my BOV (which creates a boost leak so you dont build any boost) and went for a drive...so pretty much i was NA and it didnt make a difference. Car still broke up in the same area about the same throttle %...so its not turbo related

hmmmm My problem sounds a little different then anyone elses....

When I first start my car and its cold (idleing) it runs fine, but then when it warms up a little bit (rpms are now at 1000) About every 10 seconds it will sound like its misfiring from the exhaust. It will break up. Now when i drive, anything under about 3000rpms and under 1/2 throttle it will run completly normal with no stutters or anything....but once i get about half throttle or more and over 3k it will pull then break up really bad (like someone just turned the power off) then it will pull again and keep doing it...basically it jerks in and out of power. Now, i am turbocharged and i dont have a cat so a bad cat is out of the question. I Replaced all of my spark plugs, changed my stock plug wires to MSD high currency ones, put a new fuel filter on and took out my injectors and inspected them/cleaned them. I have a inline MSD high pressure fuel pump and thats still working 100% (if you know anything about them, their so loud you can hear them working) But my intake fuel pump could also be bad. The car is in winter storage for right now and i didnt do a fuel pressure check yet however, It still has the stock coil packs (which have 102K on them...they were never changed when i had my new motor put in which currently has 26K on the clock)...So im gonna buy some AC delco performance coil packs and change those out....Im pretty sure thats the problem but not 100% positive...

also, Before i changed out the wires,plugs etc. i thought maybe i was running too lean with the turbo so i took off my BOV (which creates a boost leak so you dont build any boost) and went for a drive...so pretty much i was NA and it didnt make a difference. Car still broke up in the same area about the same throttle %...so its not turbo related

Hate to tell ya but i had a 3.8 maro with the same prob, although mine was mostly stock, turned out to me anintake leak on the bottom side of the #3 cyl and leaked into #5 after a nr=ew intake and gasket she was on the road again!

Don

I think i got the misfire bug. Was told by a mechanic that i need new plugs and wires. Its going to be too much money to get it done proffesionally so i need to do it myself.

I was looking for the plugs but i can't even see the damn things. I have never worked on my camaro, only bought it a couple years ago. Never had a problem with it until now.

So are the plugs on the underside of the engine? Can the wires be replaced without taking anything apart? Am i going to have to go at this from underneath the car? Do boot covers actually help on a 99?

I've got 93,000 on the car and it ran great up until 2 weeks ago. Are the later model v6's cooler than earlier models? Will i most likely get another 90,000 out of new plugs and wires?

just picked up a 97 rs 3.8l with a stumble.Buddy of mine(chrysler tech) has an obd2) (engine light was on and it had a bit of a stumble at or below 2000rpm going into a hill but not pushing it enough to drop a gear,peddle into it and it was o.k. buddy came over the next eve, went for a drive to determine hot or cold ran it hard from a stand still and a serious misfire started all the way up through (was quite impressed with the accelleration for a 6) got the code # 2 cyl misfire...started checking for bad contact (corrosion on plug wires and coil packs and #1 boot seemed loose and i did not like how two was routed)pulled plug on #2 and it was new (so is the 2-5 coil pack)that was it for the night. He decided to bring home a realtime analizer from work (quite a unit) plugged in the car info run it out on the road and the car never got any serious misfiring (it showed the odd mis on various cyl, but never consistant, nor could you feel it and no engine light! will replace wires anyway but i'm quite impressed with this car ,exceding my expectations....this is supposed to be wifeys toy but i'll have to see what kind of giddyup parts i can get for this thing..... it does start hard on first attrmpt but second time bang it's going (fuel sys. not holding pressure?)

so has anybody else gone threw and replaced plugs and wires and taken it out and as soon as the mottor warmed up the miss fire came back??? also im only haveing the problem on cylinder 3... and it only happens in the 1000 to 3250 rpm range...

so has anybody else gone threw and replaced plugs and wires and taken it out and as soon as the mottor warmed up the miss fire came back??? also im only haveing the problem on cylinder 3... and it only happens in the 1000 to 3250 rpm range...

I'm actually experiencing the exact same phenomenon right now, I've replaced the ICM, the 3-6 coil, and all plug wires......now I actually think the problem is worse! I'm just hoping it will get me to the shop tommorrow! :(

Ok, after three weeks of this, heres what I've found. I replaced the 3-6 coil (had misfires on both cylinders), the ICM, plug wires( 3 and 6 feel apart in my hands), and 3-6 plugs.

This is a 98 3.8 BTW

There was no change after the coil and module.....moderate misfiring and stumbling under load in every gear but first. After I replaced the plug wires the problem actually GOT WORSE! It then started missing in first as well under any load. Scan tool says its #4 now. After spending all day friday and saturday at my uncles shop trying to figure out what was wrong (we did a fuel system treatment, injector cleaning, throttle body cleaning, vacumme test, emissions, the whole nine yards) I still had nothing.

Finally on a whim I rerouted the #4 plug wire around the back of the engine away from 2 and 6 and removed the heat shield. As best as we can figure, it was picking up interference from the other wires or shorting out on the heat shield. Keep in mind that these are cheap autozone plug wires with no insulation other than the factory wire wrap.

My car is now a case study for my uncles ASE classes he teaches...so maybe the problem will get a little more exposure!

I went to napa auto parts to get the sheathing for my plug wires they had no idea what i was talking about so i tried to look to see if i could find it no luck maybe some one could give me a dicripition of this item or a picture upload. thanks a million great post and site.:bow:

what is wire sheathing could someone help with a picture or discription. thanks

So are the plugs on the underside of the engine? Can the wires be replaced without taking anything apart? Am i going to have to go at this from underneath the car?

Yes I did but the #3 id a ^*^* took me 2 Woble Sockets.

Do boot covers actually help on a 99?

YES! the heat kills the ends w/o em

I've got 93,000 on the car and it ran great up until 2 weeks ago. Are the later model v6's cooler than earlier models? Will i most likely get another 90,000 out of new plugs and wires?

Hard To Say. LETS HOPE SO! as engines rack the miles they can get more blowby, and otherthings shortning the life

I have had the same problems as everyone else seems to have.
So far, I have performed pretty much everything anyone else has tried on this thread. Originally, the car had a #5 misfire and EGR Pintle position codes that set regularly. I would reset them with my scanner and they would return regularly, but not instantly.

After several attempts to isolate the problem/solution, here is the list of what I have done so far:
New EGR - no change at all. Both codes still set as before.
New #5 fuel injector - no change whatsoever at all
New coil pack - some better but still would misfire and set #5 code as well as the EGR code
New plug wires (equivalent to factory, with shields, and new #5 plug) - it did get better but would occasionally set the #5 misfire code.
New coil packs so that all three are new now - The misfire problem went away.
So far, after over 2000 miles the misfire code has not returned. When I put the new wires on, I did route them so that they were not any closer to the exhaust manifolds than they had to be.
It runs good.
BUT -
Now, I still have an intermitent EGR Pintle postion error code, and I have checked everything I can find, read, or think to check. I have checked the orifices and tubes and they are clear of carbon. The EGR plug is nice and tight and no bent pins. I even removed the computer and checked the connections to it.

Still, the EGR pintle position code will set fairly often. It seems to set mostly when the car is coming to a stop and the engine speed drops quickly. It has never set when driving at highway speeds.

Anyway, for the misfire, I did all the above and it went away. My thoughts now are similar to several of the earlier posts to this thread that the plug/wires were going bad and weakened the coil packs. If it happens to me again, I will change wires and coil packs without going thru all this again. :)

If you have any thoughts on this EGR error, just post me an idea. :confused:

Thanks,
Buddy

Sorry to revive this thread, however I think I have this issue with my 2001 v6. I only notice a light miss when the car is sitting at idle. Once I hit the gas, it goes away. It is only every so often as well, ie weather change between hot/cold and damp/dry. I had a tune up 2 years ago where they replaced the plugs,cables and coils. I was looking at the cables and some of them have black marks on them....

also, Im thinking about putting the boots and heat protectors on the cables. Where do you get those? The auto parts stores around here don't seem to know what I am talking about.

Help would be awesome!
Fred

I hate to add more to the crazy #4 misfire but here are my issues and any help would be greatly appriciated.
98 camaro I have the issue where I can give it about 1/4 peddle with no problem through the gears except taking off in 1st (will buck violently. If I demand more than a quarter gas thats when I start to sputter and buck and throw a p0304 (#4). I won't get it though if it's real easy exceleration. So I changed the fuel filter, plugs, wires, coils, ignition module, and #4 injector. Did not improve the issue one bit. O2 sensor maybe? I don't know anymore. Very appravating. Should I change the wires and plugs again? HELP!

Fred,
I found the plug wire insulators at AutoZone. Online, you can find them at a variety of places such as JEGS, etc.
Sorry for such a delay in response, but I haven't logged in for awhile.:rolleyes:
Buddy

Had the same issue, replaced the coils. Car runs great now.

Guy at autozone didnt even know what the heat sheathing was, so I'm gonna run to a different autozone or pepboys and see what they have.

Has anyone considered routing some cold air to the back of the block? Maybe a 3" flex pipe from grille area up and back? Just a thought.

add me to this problem ok heres wat i got and have done.
6 codes
(2)cylinder 1 misfire
(2)egr emssion
transmission slip
o2 bank 1 sensor 2
ok
now ive replaced the plug and wire on the cylinder 1 no luck same thing
im going to try putting a new coil soon and see if that helps i found a set at my pick_n_pull for 40$ they all look aftermarket is it worth getting?
egr looked great no carbon at all so i took the tb off and found the sensor on the side of the intake was pluged up with alot of oil/grease cleaned that and now will have to clear codes and c if it comes back. there is alot of black inside the intake is this ok?

Just wondering if anyone has tried replacing their harmonic balancer for the stumbling or misfire problem. I have another type of car that was stumbling and it turned out to be the harmonic balancer but the condition was similar to the one described. Some of you have tried plugs, wires etc and still have the issue so I was wondering if this may be the problem or at least part of the problem, let me know if you have tried that. Thanks!

I have read on here that most people went to autozone and bought new coil pack`s and it did not fix the misfire problem, So I had tha same misfire problem with a po300 code, I changed plug`s and wires but still had a misfire so i went to autozone and bought 3 new coil`s and I looked at them and they looked like reman coil`s and the guy at the store said they were new and if it did not fix my problem just bring them back.... Well they did not fix the problem so I took them back and went up the street to a different auto part`s and there coil`s were packed in a box with foam to protect the coil`s during shipping, unlike autozone`s and I installed them and the problem was fixed and the car run as good as new !!!!! How many of autozone`s coil`s are the bad coil`s off of other peoples car`s that switched the good coil and returned the bad coil. I just though I would put in my two cent`s on my missfire misshap !!!

I found this thread via google and had the same exact problem. I have a 1998 3800 Camaro, automatic and no mods. 85,000 miles. Hesitation under throttle, bumpy idle, less power and a few backfires. I thought it was a fuel-pressure problem, so I switched out the fuel pump. After tons of fun and 6 work hours later, the problem went away for a few days but came back. Strong misfire occurred, check engine light started flashing. It threw a misfire on number 6 code. After reading this thread, I bought all new coils, cables, plugs and DEI "protect-a-boot" covers. Install took quite a bit of time because the #4 plug is quite a problem to take out and put in a new one. What was kind of interesting was that the #4, #5 and #6 cylinders already had metal boot covers which looked OEM. Maybe they were installed during the recall? Who knows. They work great apparently. I still used some silicone to seal them up.

But now shes running like a top. Smooth, stable idle. Reliable torque and a "like-new" engine feel.

THANK YOU THANK YOU THANK YOU to the original poster and other input offered in this thread. Hope my experience helps this case of questionable engineering.

Alright well I pretty much have the same problem as everyone with a few exceptions. I had AutoZone coils on mine 3800 and I replaced them all with NAPA ones. Now that still hasnt fixed my problem. So all that was said and done, I have replaced the ICM 3 times all under warranty. I replaced all plug wires and plugs with E3 plugs. And STILL with the spark plug tester, im getting a missfire out of the #2 coil. I have been getting this for the last 3 months now and I c ant figure it out. I dont know what else to do!!!!