I still haven't changed a coil pack yet, but the interesting thing is that the misfire seems less prominent or even almost non-existent in the cooler weather, but when it gets up above 85 or so, it rears its ugly head stronger. Anyone else experienced a misfire that varied with the ambient temperature?

Next I need to see if it is different when it rains/high humidity vs dry out...

 

I think I remember someone telling me in another thread that coil packs could become weaker as they heated up. I changed all of mine and my misfire went away. Today, for the first time, the light started flashing while sitting idling, code was a 300, random misfires but I could not tell it was misfiring, before, I could hear it and the car would not pull itself.

 

I just had a terrible 305 misfire. Changed plugs and wires on my 96 with no luck. Had previously changed a coil pack and ended up changing the other 2 which fixed the problem. When I took them off they were both cracked on the bottom. It isn't difficult to do and not expensive either. Worth the try I would say.

 

Thanks for the inputs. The P0171 System Too Lean (Bank 1) trouble code is back and I also had the P0305 Cylinder 5 Misfire pending code come back (SES light just blinks at WOT), so my car is back at the shop, since I have an extended warranty with zero deductible, they can pay for the T&M.

The tech at the shop said that they previously swapped coil packs and the misfire stayed on the same cylinder, which sounds odd. They did not try actually replacing the coil pack. The shop techs seem very stubborn to the suggestion, and he tried to tell me that a coil pack shares a common ground again. As Z28Pete pointed out, there are two routes. Perhaps multiple coil packs are bad as dgreenw7 found on his?

If these coil packs fail so often in 3800 Camaros, is it because they're under the cowl and subject to more heat than if they weren't? It seems like a design flaw since this seems a common failure point on these cars.

 

Hmm. There's a possibility it could be the ICM, but it doesn't commonly fail. The coil packs on these cars don't fail as often as you think, what makes it seem common is when 2 or 3 people on a forum have a problem, it gets magnified. Try switching the coils yourself if you don't trust them, it's easy to do.

 

I think the coil failing is pretty common across the board. 3.1,3.4 or 3.8s and its been like that for the last 18 years or so.

Keeping plug wires to long kills the coils. Its not a design issue its a maintenance issue. You keep a plug wire so long that 80,000 volts is not enough to get thru it, I am sure that voltage will find a way out.

 

So the update is the cylinder 5 coil pack was replaced by the shop, and we shall see if the problem has truly been nailed. ;-)

 

So what have you guys found are good intervals for plug/wire replacements? I usually replace them at the same time, but not unless I see/feel a problem...

 

No more then 5 years for my pesonal cars. You can get 6 or even 7 out of them but you are putting your coils at risk.