The great misfire mystery
12-13-2008, 07:24 PM
#91
Registered User
Join Date: Dec 2008
Posts: 1
Misfire
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 !!!
03-04-2009, 07:31 PM
#92
Registered User
Join Date: Mar 2009
Location: Valencia, CA
Posts: 2
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.
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.
08-25-2009, 05:08 PM
#93
Registered User
Join Date: Aug 2009
Posts: 14
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!!!!
12-15-2009, 12:45 AM
#95
Registered User
Join Date: Apr 2000
Location: Sacramento
Posts: 42
hi, bro
i am not an expert but:
1. check the hood for leaks
2. check if any water gets under hood onto the contact points.
3. Check both contact points of your wires. A---> B All of them.
4. Check the integrity of your wires. ( simply, if u think the're old = replace)
5. Fuel injection system: check the cleaner (don't know how to say it in eng. I am russian, sorry) Might be with the moist in the air, the crap there gets bigger.
p.s. From what you described it, sounds like i pure electrical problem.
this might seem weird but:
open the hood and **** her up with water, see what she'll do. If she misfires under that condition, u got an external problem.
I am not an expert, but hope my .02 wil help.
i am not an expert but:
1. check the hood for leaks
2. check if any water gets under hood onto the contact points.
3. Check both contact points of your wires. A---> B All of them.
4. Check the integrity of your wires. ( simply, if u think the're old = replace)
5. Fuel injection system: check the cleaner (don't know how to say it in eng. I am russian, sorry) Might be with the moist in the air, the crap there gets bigger.
p.s. From what you described it, sounds like i pure electrical problem.
this might seem weird but:
open the hood and **** her up with water, see what she'll do. If she misfires under that condition, u got an external problem.
I am not an expert, but hope my .02 wil help.
12-17-2009, 10:27 AM
#97
Registered User
Join Date: May 2000
Location: Charleston, SC
Posts: 4,738
Can't believe this thread is still going....
Kind of random, but I swapped teh plugs once, but I used the same wires all the way up to November 2007. So almost 4 years no issues.
Kind of random, but I swapped teh plugs once, but I used the same wires all the way up to November 2007. So almost 4 years no issues.
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...
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...
12-17-2009, 10:29 AM
#98
Registered User
Join Date: May 2000
Location: Charleston, SC
Posts: 4,738
Try swapping a coil pack to see if there is an issue with the coilpack, and the misfire moves to another cylinder.
03-01-2010, 06:16 PM
#99
Registered User
Join Date: Mar 2010
Posts: 1
Great thread!!!
Just joined this site because if this thread. Great info in the beginning of it. Was wondering why my tune-ups were only lasting about 8,000 miles. I did notice some heat damage but nothing that really made me worry, guess I should have looked a little closer. My wires have a lifetime warrenty though so i'm not going to spend $40 or more to protect them from heat. I thought of a cheaper method using wire loom and then I will rap in aluminum insulating tape. The tape i'm going to use has a reflective aluminum coating wich should keep some heat off the wires (and the plastic loom should keep them from arcing on the aluminum). I guess i'll post back in this site in about 6 months and find out if it worked. Thats usually how long my tune-ups last before the wonderful P0-300. Total cost for shielding about $8 and will be covering all 6 wires.
I have replaced plugs and wires everytime the misfire came up and all three coil packs last time, still to no avail. This time I did a backpressure check on the muffler and catalytic converter and a fuel pressure check/regulator check/ leak down. Everything was ok, just bad plugs and wires again. I use bosch or AC delco plugs and bosch wires everytime. So hopefully trying to shield the heat a little will keep me out from under the hood a little longer this time.
P.S. 98 Camaro 3800, paid on call firefighter and hazmat tech so this car has lights and siren and the engine gets stomped on. Poor thing!!!
I have replaced plugs and wires everytime the misfire came up and all three coil packs last time, still to no avail. This time I did a backpressure check on the muffler and catalytic converter and a fuel pressure check/regulator check/ leak down. Everything was ok, just bad plugs and wires again. I use bosch or AC delco plugs and bosch wires everytime. So hopefully trying to shield the heat a little will keep me out from under the hood a little longer this time.
P.S. 98 Camaro 3800, paid on call firefighter and hazmat tech so this car has lights and siren and the engine gets stomped on. Poor thing!!!
06-05-2010, 12:16 PM
#100
Registered User
Join Date: Jun 2010
Posts: 1
I had the same problem of misfire with my 96 Camaro 3.8l. I replaced wires, plugs, fuel pump and filter, MAF sensor, and coils. Ran good for a while but then would misfire when it was rainy or snow had melted off the car. Water runs down onto the coils from above where the air inlets and wipers are located. Replaced all the coils and made a plastic deflector attached using the plastic rivets for the weather strip (which didn't/doesn't stop the rundown of water). It is now good. Thanks to all who previously posted in this thread. It's good to know you're not alone with the problem.
Last edited by zoomerboomer; 06-05-2010 at 12:18 PM.
03-30-2011, 08:56 AM
#101
Registered User
Join Date: Jul 2009
Posts: 75
Re: The great misfire mystery
hi, bro
i am not an expert but:
1. check the hood for leaks
2. check if any water gets under hood onto the contact points.
3. Check both contact points of your wires. A---> B All of them.
4. Check the integrity of your wires. ( simply, if u think they're old = replace)
5. Fuel injection system: check the cleaner (don't know how to say it in English. I am Russian, sorry) Might be with the moist in the air, the crap there gets bigger.
p.s. From what you described it, sounds like i pure electrical problem.
this might seem weird but:
open the hood and **** her up with water, see what she'll do. If she misfires under that condition, u got an external problem.
I am not an expert, but hope my .02 wil help.
i am not an expert but:
1. check the hood for leaks
2. check if any water gets under hood onto the contact points.
3. Check both contact points of your wires. A---> B All of them.
4. Check the integrity of your wires. ( simply, if u think they're old = replace)
5. Fuel injection system: check the cleaner (don't know how to say it in English. I am Russian, sorry) Might be with the moist in the air, the crap there gets bigger.
p.s. From what you described it, sounds like i pure electrical problem.
this might seem weird but:
open the hood and **** her up with water, see what she'll do. If she misfires under that condition, u got an external problem.
I am not an expert, but hope my .02 wil help.
Okay... Our Russian Compadre here is absolutely correct!This post addition points exactly to the source of what started me down the the path to getting "Lost in OptiSpark land". Several weeks ago... just after a very heavy heavy rainfall... My 1993 Camaro Z-28 Lt-1 would not start. Period. Even though my car has less than 73,000 Miles on it... I assumed that because of the age of the vehicle that more than likely, any combination of a failure in the Optispark Distributor, spark plugs or spark plug wires were the probable culprits.
So I went through the process of changing out everything... including making the mistake of installing one of those < $100.00 cheap Optis... and finally bought a decent Delphi Optispark Distributor and put it all back together. Naturally... the engine fired right up but I had the additional problem of having a very loose spark plug and this will be covered in another thread.
Nonetheless... time passes...the engine consistently starts without any trouble...until it rains a torrential downpour. Once again... the car just would not start. On inspecting under the hood... I could not believe how much water and condensation had covered absolutely everything inside the engine compartment. I scratched my exasperated noggin for a minute and yelled out... "WTF?" It was then that I remembered being puzzled after seeing how much flaky rust and corrosion was present on the left rear portion of the exhaust manifold when I R&Rd them to replace the gaskets...which were completed rusted through... and that prompted me to look up under the hood...and Voila!
The problem here is caused by three things:
1. The hood louvers vibrate loose from their insert points over time.
2. If you have heavy rain weather, the water will leech under the hood and flow all over the place when the water flows in between the underside of the hood and the insulation pad attached there. Water weighs 64 lbs per cubic foot and so, with enough of it migrating inside the closed hood...eventually it gets heavy enough to cause the heat insulation pad to degrade, tear and the water it was holding will dump out all over the engine.
3. If you park your car on an incline with the nose of the car positioned on the elevated end... the problem will be much worse because the channel cuts in the hood will act like water sluices and cause even more water to pour down inside the hood and all over the motor.
The solution I've come up with is to simply replace the old inserts or in the absence of finding them on eBay or elsewhere...just remove the old hood inserts and use s heavy application of Permatex Black RTV to water-proof and seal up the hood ...for good!
Thanks for the "Occams' Razor" insight, Maxik!
This link to my photobucket shows the components involved:
http://s557.photobucket.com/albums/s...CAMARO%20Z-28/
Last edited by rsm93z28; 04-01-2011 at 07:57 AM.
04-13-2011, 12:41 PM
#102
Registered User
Join Date: Jul 2009
Posts: 75
Re: The great misfire mystery
I searched the entire site and failed to locate the proper original thread that might have already covered this material. So if this field has already been ploughed... please let me know and I'll delete this wordy (but I think ultimately very useful) post:
The Great Misfire Mystery for me is over. The engine is fixed and running with great power and smoothness! Here is how it happened:
Okay... and so finally... I have gone entirely through "OptiSparkLand" and emerged in one piece... but not before doping out practically every imaginable thing under the sun to solve the problem of the engine stumbling and misfiring after installing almost all the sensors, a GM approved Delphi OptiSpark unit, AC-Delco factory numbered spark plugs. AC-Delco factory approved spark plugs, New MAP Sensor, New IAT Sensor, New IAC Valve, Throttle Body Service, New PCV, New re-hosing all the vacuum lines, New NASCAR quality heat protective insulated full wire length boots, BNIB (Brand New In Box) Alternator, New GM Water Pump and drained, cleaned & re-filled the coolant system.
But in the end, the problem turned out to be THIS:
Because of the firing order design of the GM small block engines... it is possible to suffer from "sympathetic crossfire" between the wires if they are NOT properly routed and secured. The purpose of the two bolt-on metal channels is more complicated than merely being there to guide the # 7 and # 8 spark plug wires around the hot flange areas of the exhaust manifolds... they also serve to stop the inductive firing of the wrong spark plugs at the wrong time (90 degrees out of phase) and in particular...the #5 and #7 cylinders are most susceptible to this occurring because they fire nearly side by side in the latter portion of the ignition pattern. On the driver's side left bank... I routed the #5 spark plug wire over the top of the metal guide and made certain to route the #7 spark plug wire underneath the metal guide right up to the break point at the #3 cylinder...and then tucked the wire in over the top of the metal guide to the very firewall where the extra long wire allows you to install the plug wire on the #7 cylinder and then do a "U-Turn" around the wire loom at the back of the engine to keep the wire and plug insert away from the hottest portion of the exhaust down flange and pipe. I used a great deal of dielectric grease; both on the OptiSpark spark plug wire boots and on the spark plug connectors to ensure that they will remain water tight and non-conductive as well.
On the passenger side (right bank) I used the shortest wires of the set as possible and started with the #8 wire routing it over the top of and behind the metal wire guide, well out of the way of the #6 and #4 spark plug wires and used as many wire loom separators as I could find in my tool chest(s) to maintain a permanent spacing all the way through the twists and turns of the wires when routed from the right side of the front of the motor.
THIS IS A VERY IMPORTANT STEP:
Before even starting to install anything... dope out which set of four wires you will use and after doing a dry run with each wire...one at a time....have a printout of the following text along with some clear plastic tape, a roll of high temp silicone "stretch and seal" tape and a pair of scissors. This is what needs printing in a clear, bold sized font:
11111111111111111111111111111111111111111
22222222222222222222222222222222222222222
33333333333333333333333333333333333333333
44444444444444444444444444444444444444444
55555555555555555555555555555555555555555
66666666666666666666666666666666666666666
77777777777777777777777777777777777777777
88888888888888888888888888888888888888888
Use the clear wide packing tape to cover the numbered text and then cut these numbered segments into 3/4" wide strips of two equal lengths; sufficiently long enough to wrap around the wire ends at the base of the rubber connectors of both ends. Secure the bottom of the strips with a 1 1/2" wide section of the silicone stretch tape.
You will not regret having taken the time to do this because in the first place...you will know instantly if you have either grabbed the wrong wire ...or have placed the plug ends on the wrong spark plugs. Likewise, if when you are checking the two images provided by "Shoebox" for the proper insertion of the wires into the OptiSpark...it will be possible to guarantee that you have plugged everything correctly. Lastly... if you ever have to remove these wires for any reason...re-inserting them properly will be a breeze.
The last trick I used to make certain of proper wire separation was to get some "Mounting Nylon Ties" from Home Depot and use them to stagger and separate the wires at any point where I thought they might come together.
Well... that is that! I hope this information gets read by anyone in need BEFORE they wind up getting duplicate parts in overkill mode. I could not be happier with the outcome. now that the wiring phenomena is under control and the engine starts instantly, runs smoothly and has a new lease of life with better power and performance than it has had in a very long time!
The Great Misfire Mystery for me is over. The engine is fixed and running with great power and smoothness! Here is how it happened:
Okay... and so finally... I have gone entirely through "OptiSparkLand" and emerged in one piece... but not before doping out practically every imaginable thing under the sun to solve the problem of the engine stumbling and misfiring after installing almost all the sensors, a GM approved Delphi OptiSpark unit, AC-Delco factory numbered spark plugs. AC-Delco factory approved spark plugs, New MAP Sensor, New IAT Sensor, New IAC Valve, Throttle Body Service, New PCV, New re-hosing all the vacuum lines, New NASCAR quality heat protective insulated full wire length boots, BNIB (Brand New In Box) Alternator, New GM Water Pump and drained, cleaned & re-filled the coolant system.
But in the end, the problem turned out to be THIS:
Because of the firing order design of the GM small block engines... it is possible to suffer from "sympathetic crossfire" between the wires if they are NOT properly routed and secured. The purpose of the two bolt-on metal channels is more complicated than merely being there to guide the # 7 and # 8 spark plug wires around the hot flange areas of the exhaust manifolds... they also serve to stop the inductive firing of the wrong spark plugs at the wrong time (90 degrees out of phase) and in particular...the #5 and #7 cylinders are most susceptible to this occurring because they fire nearly side by side in the latter portion of the ignition pattern. On the driver's side left bank... I routed the #5 spark plug wire over the top of the metal guide and made certain to route the #7 spark plug wire underneath the metal guide right up to the break point at the #3 cylinder...and then tucked the wire in over the top of the metal guide to the very firewall where the extra long wire allows you to install the plug wire on the #7 cylinder and then do a "U-Turn" around the wire loom at the back of the engine to keep the wire and plug insert away from the hottest portion of the exhaust down flange and pipe. I used a great deal of dielectric grease; both on the OptiSpark spark plug wire boots and on the spark plug connectors to ensure that they will remain water tight and non-conductive as well.
On the passenger side (right bank) I used the shortest wires of the set as possible and started with the #8 wire routing it over the top of and behind the metal wire guide, well out of the way of the #6 and #4 spark plug wires and used as many wire loom separators as I could find in my tool chest(s) to maintain a permanent spacing all the way through the twists and turns of the wires when routed from the right side of the front of the motor.
THIS IS A VERY IMPORTANT STEP:
Before even starting to install anything... dope out which set of four wires you will use and after doing a dry run with each wire...one at a time....have a printout of the following text along with some clear plastic tape, a roll of high temp silicone "stretch and seal" tape and a pair of scissors. This is what needs printing in a clear, bold sized font:
11111111111111111111111111111111111111111
22222222222222222222222222222222222222222
33333333333333333333333333333333333333333
44444444444444444444444444444444444444444
55555555555555555555555555555555555555555
66666666666666666666666666666666666666666
77777777777777777777777777777777777777777
88888888888888888888888888888888888888888
Use the clear wide packing tape to cover the numbered text and then cut these numbered segments into 3/4" wide strips of two equal lengths; sufficiently long enough to wrap around the wire ends at the base of the rubber connectors of both ends. Secure the bottom of the strips with a 1 1/2" wide section of the silicone stretch tape.
You will not regret having taken the time to do this because in the first place...you will know instantly if you have either grabbed the wrong wire ...or have placed the plug ends on the wrong spark plugs. Likewise, if when you are checking the two images provided by "Shoebox" for the proper insertion of the wires into the OptiSpark...it will be possible to guarantee that you have plugged everything correctly. Lastly... if you ever have to remove these wires for any reason...re-inserting them properly will be a breeze.
The last trick I used to make certain of proper wire separation was to get some "Mounting Nylon Ties" from Home Depot and use them to stagger and separate the wires at any point where I thought they might come together.
Well... that is that! I hope this information gets read by anyone in need BEFORE they wind up getting duplicate parts in overkill mode. I could not be happier with the outcome. now that the wiring phenomena is under control and the engine starts instantly, runs smoothly and has a new lease of life with better power and performance than it has had in a very long time!
Last edited by rsm93z28; 04-13-2011 at 12:50 PM.
11-03-2012, 04:27 PM
#104
Registered User
Join Date: May 2000
Location: Charleston, SC
Posts: 4,738
Re: The great misfire mystery
Went to a rifle range, on a long bumpy dirt road, and on the way then as soon as I turned of and accelerated up to about 70, misfireing the whole way. I am assuming a wire hitting the exhaust or something. Don't know age of ignition, but it looks like a factory install so I am going to throw some new plugs in and inspect the wires and go from there.
Last edited by MustangEater82; 11-03-2012 at 05:14 PM.
11-04-2012, 06:10 PM
#105
Registered User
Join Date: May 2000
Location: Charleston, SC
Posts: 4,738
Re: The great misfire mystery
Long story short....
replaced all 6 plugs, ohmed out wires, wires were good, new plugs in. I noticed a spot where it looked like the wires were riding and possible arcing, I protected that area and wrapped the wire in some common aircraft grade tape that is good for insulating up to 34,000 volts.
Still had a fire, drove to store, pulled code, said my #5 cylinder was misfiring, I got all new wires, replaced them, car still misfired drove it back to store, still #5, so I picked up a coil. Put new coild in and all was good. Visually checking the coil the #5 side looked good, the other side looked corroded and messed up.
Whatever, all is good now, car runs great since well I bought it 20k miles ago and have no clue when plugs/wires were last changed. I kept the wires just incase something wiered happens since they seem to be ok.
replaced all 6 plugs, ohmed out wires, wires were good, new plugs in. I noticed a spot where it looked like the wires were riding and possible arcing, I protected that area and wrapped the wire in some common aircraft grade tape that is good for insulating up to 34,000 volts.
Still had a fire, drove to store, pulled code, said my #5 cylinder was misfiring, I got all new wires, replaced them, car still misfired drove it back to store, still #5, so I picked up a coil. Put new coild in and all was good. Visually checking the coil the #5 side looked good, the other side looked corroded and messed up.
Whatever, all is good now, car runs great since well I bought it 20k miles ago and have no clue when plugs/wires were last changed. I kept the wires just incase something wiered happens since they seem to be ok.
