Misfiring Issue

[ne0hisda0ne]

Hey Guys,

I've posted this at afbforums.com but most of them are V8 owners and don't really know anything about our V6. Couple months back, my car started misfiring at above 5 grand. So since I didn't have the money to diagnose and fix I just didn't go over 5 grand. Knowing this is prolly an ignition problem, I figured it would just be a simple coil replacement. Ok, now last week I was about to leave from work, jumped in my car and started her up. Right when she starts up I can tell she's misfiring BAD. I can smell gas, so that's telling me I'm getting fuel, but something isn't sparking. SO I immediately go to the closest part store and purchase a coil. I get back and replace the oldest coil (replaced all 3 in the 7 years I've owned her), figuring that would prolly be my culprit. Started her up and same issue. I've checked wires, not plugs yet, but I will soon. SO I started swapping coils around to try to get the bad one out of the loop. It seems that any combo still gives me the same result. I also started taking one plug wire off at a time and seeing if the car will get worse and I think it was fine one everyone of them as if leaving a wire off didn't make it get worse. So I'm stumped now. Could this be a control module or just a coroded spark plug? I have a 1998 Camaro V6 with modified 80 series suckmaster dual exhaust, modified air intake box (still have the baffles) and I have ported my heads (getting ready for headers). I have also replaced my catalytic converter many times in the past because I have had misfire issues before. I've also rebuilt pretty much the whole top of the engine except fuel injectors (which may be my culprit, maybe). Anyone got any other ideas maybe?

[bigbrian442]

Re: Misfiring Issue

do you have a check engine light? If so it will tell you the cylinder that is miss firing. You could have more then 1 bad coil.

[cam98aro]

Re: Misfiring Issue

pull your plugs or put a timing light on and see which ones arent firing

[J.T.]

Re: Misfiring Issue

Also even wires that look good can be bad. Learned that lesson yesterday.

[flamingchicken]

Re: Misfiring Issue

werd, even a small crack can allow arcing.

[Rob Bell]

Re: Misfiring Issue

Try running it in the dark and look for arcing. You could also pull the ICM and get it tested at probably most parts stores... I'd call first though.

[ne0hisda0ne]

Re: Misfiring Issue

do you have a check engine light? If so it will tell you the cylinder that is miss firing. You could have more then 1 bad coil.

That's what boggles me, actually no it isn't coming on. Last time it came on was over 2 weeks ago for my damn EGR valve, which I refuse to replace as I will remove it and install a delete kit and remove the code from the computer, figuring while I was in there I'd play with parameters (by a pro of course, not me, I'll just be dishing out the green). So yeah in the past the SES light would go off and I would run to autozone and it'll tell me it was misfiring on cyclinder (enter number here) and then I'd diagnose it that way. *sigh*

[ne0hisda0ne]

Re: Misfiring Issue

pull your plugs or put a timing light on and see which ones arent firing

yeah, I need to borrow someone's timing light. Ok so I read somewhere that you can test the resistance of the coils, so I did and I get 2 different reading from all 4. (old-6.5k, new-6.5k, old-8.5k and (on the bench) old-8.5k) anyone know what our coils resistance should be?

[inheritthefire]

Re: Misfiring Issue

I'm not sure about the coil resistance, so I can't really help you out there...

But, I had a similar problem about a month ago, where my car would misfire while idling, and it got to the point that at low rpms, if there was a stress on the engine it would actually stall out and die on me.

Took it to a mechanic, who, at first glance, said it was most likely a computer issue, and/or a fuel pump.

After a bit of poking and prodding, he figured out it was actually a fuel pressure sensor. My car was running way too rich, practically the entire winter.

These cars are definitely a love/hate relationship...

**Edit - Forgot to mention, my car did throw a code, it ended up being a P0300, random/multiple cylinder misfire.

[ne0hisda0ne]

Re: Misfiring Issue

I hope it's not a fuel pump, isn't the fuel pump located in the fuel tank? Heard that's a nightmare. Is this true?

Just some history I have recently replaced my fuel filter, so I don't think that's the issue.

Also if I smell fuel when starting it and giving her some gas would this still point towards a fuel pump? I assumed it was just squirting gas in a cylinder that wasn't getting fire.

[cam98aro]

Re: Misfiring Issue

I hope it's not a fuel pump, isn't the fuel pump located in the fuel tank? Heard that's a nightmare. Is this true?

Just some history I have recently replaced my fuel filter, so I don't think that's the issue.

Also if I smell fuel when starting it and giving her some gas would this still point towards a fuel pump? I assumed it was just squirting gas in a cylinder that wasn't getting fire.

the fuel pump is located in the tank, and you can either drop the tank (which is a PITA) or cut a hole in your hatch to access the pump

if you smell fuel, it means that your engine is getting fuel and flooding out, or there is a fuel leak somewhere i would guess that your fuel pump works, but you can always test your fuel pressure to see what it is at.

[ne0hisda0ne]

Re: Misfiring Issue

the fuel pump is located in the tank, and you can either drop the tank (which is a PITA) or cut a hole in your hatch to access the pump

if you smell fuel, it means that your engine is getting fuel and flooding out, or there is a fuel leak somewhere i would guess that your fuel pump works, but you can always test your fuel pressure to see what it is at.

Damn, that's what I figured, well atleast I have some more things to check if all esle fails. I thank you everyone for your advice. Hopefully just replacing coils, module, wires and plugs will fix this issue. I was just curoius if anything else could cause my symptoms. And as I suspected there are. *sigh* :cry:

[cam98aro]

Re: Misfiring Issue

Damn, that's what I figured, well atleast I have some more things to check if all esle fails. I thank you everyone for your advice. Hopefully just replacing coils, module, wires and plugs will fix this issue. I was just curoius if anything else could cause my symptoms. And as I suspected there are. *sigh* :cry:

do plugs and wires before anything else

having a misfire can foul a plug out and it may never be the same again

i know on my other car, it was running rich and the plugs wouldnt work right until i cleaned them completely, and then put them in the spark plug cleaner

[ne0hisda0ne]

Re: Misfiring Issue

Well I did them last year around the same time, so I guess that's why I'm a lil' confused...plugs should last longer than a year right?

[flamingchicken]

Re: Misfiring Issue

That's what boggles me, actually no it isn't coming on. Last time it came on was over 2 weeks ago for my damn EGR valve, which I refuse to replace as I will remove it and install a delete kit and remove the code from the computer, figuring while I was in there I'd play with parameters (by a pro of course, not me, I'll just be dishing out the green). So yeah in the past the SES light would go off and I would run to autozone and it'll tell me it was misfiring on cyclinder (enter number here) and then I'd diagnose it that way. *sigh*

so if you go out and romp the hell on it, it doesnt throw a light? mine was missing so bad at one time that the ses light was actually blinking.