Sick Computer?

[Boosted92LX]

What a way to start... Bought my first SN95 last Friday. 97 GT. Ran beautifully, was very pleased with it. It did throw a CEL on the way home, and I stopped at an auto zone to get a scan. Only code was insufficient catalyst. I figured the high flow cats just weren't doing enough and MIL eliminators would solve that...Still ran fine. I don't know if it was coincidence or not, but drove it in an incredible rain storm the next day and it hasn't been right since. Intermittent dead miss. Rough idle that comes and goes. Threw more codes, P0153- o2 slow response, p0420-bank 1 catalyst below ... p0430- catalyst below bank 2, p1150 lack of ho2 switches fuel at trim limit. p1152 lack of " " sensor indicates rich.

I removed plug wires to check for water, found none. Replaced coil packs with spare set, car ran better for 30 minutes... miss came back. replaced plug wires with good wires. (also spare) Miss went away for about 30 minutes, this time CEL cleared... then came back along with the miss.


What's bad about all of this is the engine problems come and go. Anytime I've ever had a bad o2 sensor the car ran bad ALL THE TIME. I just went through this crap with my fox, changed o2's, plugs, wires, etc etc all the while the codes were telling me I had o2 sensors out, and it wound up being a bad pcm. Replaced that and it ran like a new car. Just like my 97, the problem was intermittent.


So, past experience tells me to replace the pcm, codes tell me to replace o2 sensors. Thoughts or suggestions?

EDIT: Jacked the car up and disonnected all of the 02 sensor connections looking for water. Found none, sprayed connections and reconnected. No change.

 

[5.0Droptop]

Check the puter make sure no water there? Maybe water leaking in somewhere.

Clean the maf meter

 

[Boosted92LX]

Check the puter make sure no water there? Maybe water leaking in somewhere.

You know I thought about that for about 5 seconds, then thought naw, no way. I'm going to check it and see, I guess.

Clean the maf meter

I'll try this.. but wouldn't it cause continuous problems as opposed to intermittent?

BTW, thanks for replying Shawn. Hope you get to feeling better, bud.

 

[5.0Droptop]

Does it have a in fender air filter on the end of a cold air kit? If so check the filter as well.

 

[5.0Droptop]

You know I thought about that for about 5 seconds, then thought naw, no way. I'm going to check it and see, I guess.



I'll try this.. but wouldn't it cause continuous problems as opposed to intermittent?

Hard to say. The computer can compensate but if it swings from one extreme to another it cannot keep up.

 

[Boosted92LX]

Does it have a in fender air filter on the end of a cold air kit? If so check the filter as well.

It's got a BBK CAI with a K&N in the fender. Will check..

 

[Boosted92LX]

4.6

 

[5.0Droptop]

If the filter is wet that could slow air flow. i would think that could cause issues.

The sensors read rich. Lack of air flow.
Dirty maf
Maybe a sensor.

 

[Boosted92LX]

Agreed, but it's had 5 days to dry out. I'm thinking maybe just dirty, then on top of that maybe wet kicked the whole thing off? I did pull plugs and look at them. amazingly they're not fouled.

 

[5.0Droptop]

You will find it.

 

[Boosted92LX]

I'll check that maf tomorrow and buy a cleaner/oil kit for that K&N... Good direction. Thanks Shawn.

 

[5.0Droptop]

I hit a huge puddle one time and it killed the wideband sensor in my wife's car.

 

[5.0Droptop]

I'll check that maf tomorrow and buy a cleaner/oil kit for that K&N... Good direction. Thanks Shawn.

Mske sure you follow the directions on oiling the filter. People tend to over oil them and not let the filter sit as instructed and then the oil fouls the maf.

Maybe the filter was really dirty and got wet the crusted up.

 

[Boosted92LX]

It's gotta be on the intake side. No way 4 o2 sensors all go out at once.... although that would be my luck.

 

[5.0Droptop]

It's gotta be on the intake side. No way 4 o2 sensors all go out at once.... although that would be my luck.

That was my thought process as well.
But I've been wrong before.

*waits for someone to post a book of things to check*

 

[Boosted92LX]

I'm out- good night!

 

[5.0Droptop]

Later mang.

 

[ChuckStyles]

I worked on a few of these cars over the years and I'd check the intake tubes running from the main tube to the plenum.

Did you look underneath the car? Had a friend install an aftermarket midpipe and he didn't zip tie the o2 sensor wires so the insulation melted and screwed them all up.

 

[Boosted92LX]

Yeah i checked the wires under the car for damage, they were good. Will also look at intake tubes, thank you!

 

[5.0Droptop]

Did you check your tach gear. Ive seen them wear down and throw the computer off.