Rain/Idle Issues

**JoshieDoom** · 12-15-2008, 05:30 AM

Anybody have any rain problem with their f-body?

Seems like if i drive my car in the rain its fine, but as soon as i let it sit in the rain with it idling it starts acting like its missfiring, shaking the whole car, even lurching at idle in drive.

Engine is dry as a bone, filter is dry... PCM is wet... could this be it???

BTW... no codes...

**shady milkman** · 12-15-2008, 05:34 AM

:nilly; shit your pcm is wet? water might be pooling around the pcm..causing little shorts..try putting a rag or doing the pcm/wire delete mod ....good luck.

**JoshieDoom** · 12-15-2008, 05:36 AM

Probably buy a stainless cover today.

Read a few over on tech with these issues. Im gonna lube up the connectors and see if it helps.. cant be good for the pcm

**shady milkman** · 12-15-2008, 05:39 AM

Originally Posted by JoshieDoom

Probably buy a stainless cover today.

Read a few over on tech with these issues. Im gonna lube up the connectors and see if it helps.. cant be good for the pcm

in general water+ electrical equipment = fail ...might be a good time to get a 99+ pcm and have frost..or you if you have the software...tune it for a 98 and re-pin it into the car

when i get my hp tuners i will be doing that..so i can tune on the fly

**JoshieDoom** · 12-15-2008, 05:51 AM

hmmmmmm....gas guage doesnt work tho does it?

**shady milkman** · 12-15-2008, 05:55 AM

Originally Posted by JoshieDoom

hmmmmmm....gas guage doesnt work tho does it?

yea it can..i believe hp tuners has to do something..like splice in an ecovan's gas settings thingy...then it works

**JoshieDoom** · 12-15-2008, 05:59 AM

Originally Posted by shady milkman

yea it can..i believe hp tuners has to do something..like splice in an ecovan's gas settings thingy...then it works

I have to get back out soon so Ill throw some aluminum tape over it and see if it still does it

**hutch1999** · 12-15-2008, 07:11 AM

water is getting in the connections of your o2s most likely. Disconnect them and use dielectric greese inside the connections. Or your o2s could be going out also.

I had the same exact problem as you

**Firebirdjones** · 12-15-2008, 07:25 AM

Wow,,,I think I would look first into why that PCM is getting wet in the first place. Sounds as though you have a rear hood gasket leaking or something up in that corner of the car letting water in. Shouldn't be happening though,,,mine stay bone dry. I never understood why GM stuck those damn computers out there anyway, seems much safer under the passenger side dash where they used to be,,,much drier,,,less temperature variance etc...

**JoshieDoom** · 12-15-2008, 07:51 AM

Aftermarket hood...

A cover will fix it i think.

Ill check the 02s next time I get it in the air. You can hear it popping in the exhaust really loud when it does it, the cutout magnifies the sound a ton.

**Firebirdjones** · 12-15-2008, 08:10 AM

Um,,,get rid of the aftermarket hood??? If it's not sealing the back properly then it's not worth the money,,,or you need to find a solution to sealing that thing properly. The gasket is actually on the cowl,,,why is the aftermarket hood not sealing???

Maybe it's just me but the water getting in is the main problem here,,,no?? Simply covering the computer is a bandaid fix that isn't solving the real problem here..

**Firebirdjones** · 12-15-2008, 11:17 AM

Something else you could check that I forgot to mention would be to pull the screens and check the rain gutters in the corners of the cowl. It's common for debri to collect in there and not allow the rain water to run off as it should.

**JoshieDoom** · 12-15-2008, 09:15 PM

You buy me an 800 dollar hood and have it painted and ill do whatever you like

I honestly dont know what the main issue is. Could be the 02s, could be the computer.. dont know really. Seems like the 02s would throw a code. The cover would be a permanent fix. The car is a dd with 155k. Its not perfect by no means

**hutch1999** · 12-16-2008, 07:39 AM

sometime if you throw codes but the light is off, mine was somehow like that. Take it to someone with a good scanner that show code history.

**Firebirdjones** · 12-16-2008, 08:41 AM

Originally Posted by JoshieDoom

You buy me an 800 dollar hood and have it painted and ill do whatever you like

I honestly dont know what the main issue is. Could be the 02s, could be the computer.. dont know really. Seems like the 02s would throw a code. The cover would be a permanent fix. The car is a dd with 155k. Its not perfect by no means

I thought your issue was the pcm being wet??? Thats what I gathered in your first post. Then you alluded to your hood being aftermarket when I said your cowl seal may have been leaking,,,as if the hood was the issue???

Maybe I'm reading you wrong here. I am by no means trying to insult your hood. Sorry if it cost you $800 but for that kind of money it better damn well seal the cowl or I'd be sending that thing back. Just my humble opinion.

But that PCM should not be getting wet, and I would eliminate that threat first before chasing around other ideas. Especially since you said the car acts up when sitting in the rain,,,which would give a chance for the water to pool in the corners of the cowl area. Niether of mine pool water in those areas in the rain, which leads me to believe you have a clogged water drain in the cowl corner,,,or that hood seal is not sealing??

**JoshieDoom** · 12-16-2008, 10:16 PM

98 is different. PCM is different. I looked at it while putting on the ac drier decal. I didnt buy the hood BTW. it was on the car when i got it, i would have went OEM which i will. The 98 allows water to be run off on the damn computer. Seal stops right in the middle allow it to drain right on it. Hutch said his problems like this was the 02 sensors but when its dry and i wash my car and dump the suds on the windshield it does it . Pretty sure its the ecu. No insults were taken btw

Ill will buy the cover and report back

**hutch1999** · 12-17-2008, 06:40 AM

well good luck. btw mine was fine until water was splashed directly underneath the car.

If it is the PCM ls1tech has them pop up in the classifieds

**typhoon1110** · 12-17-2008, 08:48 AM

could be a coil getting wet and shorting

**0rion** · 12-17-2008, 01:55 PM

Originally Posted by Firebirdjones

Something else you could check that I forgot to mention would be to pull the screens and check the rain gutters in the corners of the cowl. It's common for debri to collect in there and not allow the rain water to run off as it should.

this is the first thing that came to my mind. I would pull those screens and make sure your drain is not clogged over there.
The next thing I would do is put electrical grease in all the plug boots on both the plug side and the coil side. What wires are you running on it?

**JoshieDoom** · 12-17-2008, 08:58 PM

Stock wires. Changed them 1/2 a year ago and globbed the dielectric grease to them on both ends.

Never had an issue till about two months ago.

Ive heard of getting a spray bottle at night and while the car is running spray parts of the engine and listen for a miss and look for a spark.. I have yet to do that.