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-   -   The great misfire mystery (https://www.camaroz28.com/forums/v6-tech-22/great-misfire-mystery-78028/)

gig 02-05-2003 09:46 PM

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.

kahouna23 02-06-2003 12:21 AM

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:

ImportKILLER 02-06-2003 12:46 AM

Good looking out bro. :)

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

96 camaro 4 life 11-25-2003 11:11 PM

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!

morb|d 11-27-2003 05:07 AM

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. ;)

MustangEater82 02-05-2004 10:26 PM

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

thank you :)

gig 02-07-2004 08:30 AM

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?

viper03af 02-09-2004 02:04 AM


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.

00SilverStar 02-09-2004 10:41 PM

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

MustangEater82 02-10-2004 01:26 AM


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 :)

viper03af 02-10-2004 01:32 AM


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:

JoeMack 02-25-2004 01:20 PM

bucking
 
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

00SilverStar 02-25-2004 06:23 PM

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.

gig 03-02-2004 04:14 AM

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.

stangkilla1 03-05-2004 06:27 PM

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


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