damn misfire gallore

every damn time it rains out or is wet/damp, my car misses like a bastard. I have my o2 sensor connections wrapped up with electrical tape and my PCM is in a plastic bag since thats a common problem on these damn F-bodys with the water running off the windshield onto the PCM.

it random misfires so bad to the point I will be in cruise control and it will start to slow down and I hafto drop a few gears to stay acclerating…

now, while its missing, if I floor it…it clears up instantly…same with anything from 75% throttle to 100%…anything under 75% it misses…

popped the hood a little while ago with it running, no arching anywhere that I can see…I am still on the stock wires with 60k on them, but their not getting wet…

the only thing I noticed that was getting wet was their was a pool of water on my intake manifold around the entire base of injector 6 from the water running off the windshield…the only thing I can come up with that is the water is seeping into the intake manifold through the injector mount and im getting water in my gas?? could this be possible??

if ur getting water in thru and injector this would also mean there is an relivant air leak which when it was dry could cause leaning issue or high idle also.

well it did this with my stock injectors, and I just put in my new injectors (new to me, used injectors) and it didnt change a thing

my idle sometimes hangs around 1500rpms-2k when I throw my car in neutral and am on the brakes slowing down, but once I stop…it idles down to a grand where the idle is set at.

as far as lean issue, my car did this before it went for the cam swap, and actually did it the morning on the way to dropping the car off at the shop…if it had a leak on the dyno and was going lean, he would have picked it up…

Is the car throwing a CEL?

I would change the plug wires and go from there. My work van had a bad coil pack on the #8 and threw a CEL. It had the same problem.

yah, only when im driving…when its missing the SES blinks, and well the power loss/sound of the car is obvious.

your van only did it when its wet out??

It did it randomly. It’ll store the code. I would try the wires first. If you still have the issue, replace the coil pack on the cyl it’s misfiring on. Bad coil packs seem to be a common problem on LS-based engines.

its random misfire…so its a P0300 code…

usually bad coil packs just pick up a cylinder misfire…and it will tell you which cylinder from p0301-p0308

when my car had the dead cylinder before, I always got the cylinder 5 misfire…the misfire just felt like a very slight vibration. I wouldnt have known it was missing if the SES didnt tell me it was…the car still had a shit load of power…

so the way my car is running now is deff. more then 1 cylinder…like I said, its a random misfire…the car wont even accelerate to the point if a bone stock civic ex pulled up next to me, he would beat me.

so something is going whacked with the whole system and its only when its wet out, but nothing seem’s to be getting wet under the hood.

its obviously an ignition issue. get some LS7 wires, replace coilpacks if needed. the water around the injector shouldnt be an issue unless your orings are bad, and if thats the case youd have bigger consistant problems. and a little water isnt a problem, most ecu connections and injector clips are a weather pack of some sort…

what could be an issue, is if the coilpack has any type of cracks in the casing water/moisture could make its way in. i know on older VW VR6’s the coilpacks would split and would cause misfire issues… start trouble shooting.

my cylinder 2 coil pack had a big chip in the corner…I threw some JB weld over it just to seal it up lol

what O2 sensors did you use, some have had problems with going with the bosch 13111’s that are long enough for the long tube headers but some people tend to have problems with them.

Do the wires, and use electrical insulating grease on all 16 boots. If you want to be cheap, just try the grease on the old wires.

If it’s not that, go for the coils. My old Grand Am would do the EXACT same thing when it was damp out, and it was because the coil was cracked, leaking and grounding out the spark with moisture in the air.

I am using the stock o2’s that came with my car with SPeedtweekerz 24" o2 extensions that came with my headers.

and on my rear o2’s I have simulators which by the way, do you want them?? I dont need them.

I will check into it

dang, when i said it could be a cracked coil allowing moisture in, i get no response… no more help from me.

nah i just deleted my rears

No I saw that…and I replied to it…

I said I have a chipped coil on the outer edge and I put JB weld over it a while ago

how much are the coilpacks, i cant imagine they are too pricey. mine are like 30-50 a piece depending on what ones you get. and GM needs to sell whatever they can.

The one I bought for my van was $70-something and that was wholesale

Let me know how much the coils are…

See sig update:ninja

Be sure to use grease on the boots as TurboTravis said… The humidity/moiture in the air could be collecting in the boots causing a missfire