I have a 95 Z28 with 126k mi on it. The car has been acting wierd the past few days. The car is way down on power, blowing out blk smoke really bad, barely idleing at all. I changed the spark plugs yesterday and all of the old plugs were real black looking. At first the car only started jerking and studdering at low rpms in a high gear (ex. 6th gear @ 1800rpms). Now it does it through every gear and it seems to be getting worse and worse.
It also throws a SES light every now and then and when the light is on, the car runs better. Is there any sensor that could be making my car think its running lean and therefore over compensating and making it run really rich?

Please help me.......this is my only car to drive.
Thanks!
Brent

 

yes, I have a feeling it's the 02's.

Go to Advance, AutoZone, O Reilys and get a OBD scanner. it will most likely say 02 lean or something.

 

Check for intake leaks, intake elbow, any emission equipment etc etc.

 

Yep, check for codes. I think that if an O2 is far enough out-of-wack, the PCM goes back into open loop, and stops looking at 02's.

But cheak your codes before you start buying parts...If it is an O2 code, you might want to look over your wirring and connections. - JM.

 

Hey, thanks for the ideas guys! I actually changed out the o2's a couple of months ago. I'm gonna go get those codes checked out tomorrow. Does the car have to have the ses light on inorder for a diagnostic tool to read it? because the light only comes on sometimes. And will those codes tell me exactly what is wrong or will it just give me an idea of where to look? As for my emissions equipment, I did away with my smog pump and all that a few years ago.

 

The code will remain in the PCM even if the light is not lit.

Here's a dumb question, have you looked at your air filter lately?

Don't bother getting some place like AZ to try to scan it. They will think the car is OBDII because of the connector you have but it's actually OBDI and they won't be able to scan it. Then they'll tell you that you have a "computer" problem.

 

nope, the light goes off and on so it doesn't burn out IIRC.

 

No. If the poblem is "active", the SES light is on. If the light goes out, the problem is no longer active, but the code is "stored".

 

You installed AC Delco O2's, right? I've seen more than a few LT1's that didn't like Bosch. - JM.