paging GMtech

[wantmorepower]

Hey....just read your reply to another post and realized that you are a pro at fixing chebies. Anyway, if you have a minute, try this on for size.

I have been struggling with a misfire problem for a few months now. So far i have been too cheap to take it to a real mechanic to fix the problem. as of now i have been playing shade tree.

Here is my problem. Repeated misfire in cylinder #6. Here is what i have done myself to try and fix the problem.

- Changed all of the plugs and wires. <--- PAIN
(Still missfire #6)
- Changed plug #6 again.
(Still missfire #6)
- Changed coil pack for #6 cylinder
(Still missfire)
- removed ignition module for diagnosis
checked out at autozone and seems to check OK.
{counter guy ran it about 8 times to make sure}
(Still missfires)
- Removed corrosion appearing build up from bottom of the ignition module and the base to which it is attached. Applied dielectric grease to the bottom of the ignition module and the base. Removed rusty looking build up on the post of all of the coil packs. Applied dielectric grease to all of the coil posts and re-connected wires.
(Still missfires)

Sitting here typing this post. Still missfires......LOL.

Really though, i don't know what to do next besides lay down the dinero to my mechanic.

Did i miss something GMtech? Is there another tree i should be barking up? I was given the advice to check for arcing but to this day have not been able to see any kind of arcing at wire number 6. If you can help me fix my problem i will forever be in your debt. LOL.

[wantmorepower]

LOL just noticed that i was a rookie... even though i have been a member since august of 2001.

[morbid]

i'm going through something similar at the moment. though my misfires were my own doing. i decided to do some 'preventetive' maintenance by replacing plugs and wires. now i've got terrible problems.

anyway, you don't mention anything about the wires. tak off the wire for #6 and test it with an ohm meter if you have one. my stock wires test at ~2.7 kilo-ohms for the longer ones like #6. if its more than 3 kohm, its probably bad.

if you don't have an ohm meter, try replacing all the wires (a major pain i know), its worth a try. i mean you seem to have changed out everything else. :D

[Gmtech1005]

ok, It is sounding like most of you ignition circuit is ok. The whole corrosion build up on the coil pack base doesn't sound too good. There is always a chance that there may be a problem with the base. You need to go pick up a spark tester. It is a spark plug looking tool that has a clamp on it that you clamp to ground. Then you plug the number 6 wire to it, and watch it with the car running. Pay attention to the spark and how good or bad it looks. Compare it to a known good cylinder.

http://buy.snapon.com/catalog/Pro.as...%5FCat%5FNAME= Ignition&store=snapon%2Dstore

That is what the tester is and looks like. Copy that and paste it and it'll take you to the site. Anyway, back to the diag. That is the easiest way to check if you have good spark to the cylinder. That will check all of the ignition up to the plug. If you have good spark to the tester. It leaves me thinking you may have a fuel delivery problem to cylinder #6. Now, the O2 sensors are most likely ok because otherwise you would have fuel trim problems on all cylinders. Your PCM or (powertrain control module) watches those o2 sensors to determine whether your engine is running rich or lean, and then adjusts the fuel trim to get the ideal mixture. So that kinda rules out an o2 system problem. You may have an injector problem. If it's not ignition, it then looks to be fuel right.. [img]tongue.gif[/img] Anyway, then you gotta check to see if you are getting a good signal to the injector. But anyway, first check the spark and make sure you don't have an ignition problem. Let me know how ya do.

[morbid]

wow, i wish i had one of these! i thought something like this might exist but then i figured that can't be because it would make everything too easy. [img]tongue.gif[/img]

[Kelly Rosato]

Go to Autozone and buy a Noid light for 6.00 and make sure that injector is getting a good firing pulse. Then swap the injector for the one next to it (#4) and see if the misfire moves to #4.

[wantmorepower]

BTW .... regarding the misfire issue. Do our cars.... 95 up 3.8 have a crankshaft/camshaft sensor? Could this be a possible or likely culprit to a specific cylinder missfire problem?

Also thanks for the advice. I am going to pick up a spark plug wire tester tonight at autozone as well as check the resistance to the #6 wire. (even though it is brand new) It wouldn't be the first time i have bought bad stuff from outozone. Thanks for the replies.

[Gmtech1005]

See, you must always look at the big picture when trying to diag a car. If the misfire is specific to cylinder #6, it must be spark or fuel delivery to ONLY that cylinder that is the problem. A camshaft or crankshaft position sensor would give your PCM incorrect readings, and you would have problems with all cylinders. You also know your problem is not related to o2 sensors, a fuel pump, or any sensors the computer depends on for running the car. Otherwise it would also give you problems across the board. Either way, you have a lot of good advice on this post, everyone that has responded seems to have a good knowlage of what they are doing. Start with the spark tester because you want to rule out a spark problem first. Test the fuel system second. You do not wanna replace a $100+ fuel injector unless it is needed. Let us know how your tests are going, and what your results are. I am interested to see how it all ends up.

[jamie]

my misfire was constant from cylinder 6. it was getting to hot, and then missing. maybe see if its getting near a manifold or something..

[Speedin96]

I had alot of problems with my car misfiring but it seemed to be my spark plug wires... for a while.. I changed them once and it took care of it but a week later they came back but without the code this time... I could feel it and it wasn't a steady misfire it was an out of rythym misfire... like a fire fire fire duh fire fire duh fire duh fire fire fire fire fire duh... I changed them again and the spark plug wires which took care of it for again... a little while now its doing it again... i've been thinking fuel injectors your fuel injector might be stopped up? I dunno that much about them thats why I'm hoping to get some help off this too

[wantmorepower]

With the weather we have been having here, i haven't even been able to think about driving the camaro. So that meant that i didn't even think about working on the camaro.

Thanks for all of the excellent replies that have been submittied. i definately have a game plan for figuring out this problem. I have the spark plug tester, multi meter, and noid light all ready to go. It definately feels good to have a plan of attack instead of feeling like a dummy because i can't figure out the gremlins in my car.

I will post the results of my shade tree adventures as i make progress. Thanks again.

One positive note..... the more and more i have to work on this car.... the less intimidating it seems.

[Only4U]

<blockquote>quote:</font><hr>Originally posted by Kelly Rosato:
Go to Autozone and buy a Noid light for 6.00 and make sure that injector is getting a good firing pulse. Then swap the injector for the one next to it (#4) and see if the misfire moves to #4.<hr></blockquote>

god that's so complicated with the old manifolds though. changing plugs is no easy chore...

[wantmorepower]

Hey i finally fixed the missfire with #6 cylinder.
It appears that the main culprit was with the use of dielectric grease on the coil post and plug wire. All of the grease that was inside the plug boot created a airtight seal around the post. So much that whenever the plug wire was set onto the coil post it would slightly pop back up as soon as i would take my finger off of it. (It would raise up about 3/16") After all of the headaches i just noticed this last night. So after swabbing out some of that extra grease the plug snapped right into placed and stayed put. Missfire #6 cured.

Now the bad news.... missfire has moved to #4 cylinder now. LOL. But now i am so good at changing these damn plugs and wires (it took me all of 5 minutes to remove the plug and wire from number 6 last night), I should have it sorted out tonight. Thanks for everyone's input on this post.

[wantmorepower]

It is finally fixed. It feels good to be able to slip it gently into first. Bring the revs up to about 1700 rpm. Drop the clutch. Smash the gas. Take of like a bat out of hell. Thanks for the help everyone. Thanks GMTECH

[Dan90RS]

Just a reminder to let you guys know that the misfire counters are not always correct. Sometimes they will count misses on the wrong cylinder.

Just a few weeks ago I was working on a FWD L36 that kept counting misses on #1. Well I was chasing #1 for over an hour before I went after it's pair, #4. Bad plug on #4 caused miss counts on #1. ALWAYS check the pair cylinder. 1-4, 2-5, 3-6.