I have a 1987 z 28. It has a 5.7 liter motor, with no catalytic converter on it. It idles rough when I have it in gear (automatic), and the SES light would come on. When I take off, the SES light would go out and it would run pretty smooth. I took it to a shop to have the code read. They told me that it was telling them that I had a bad oxygen sensor. They were going to replace it when I told them that the car does not have a catalytic converter. They told me that the SES light comes on because of my lack of a cat, so they did not replace it. I changed the wires (accell - 8mm), plugs (ac delco), cap (accell), rotor (accell) and fuel filter (ac delco). It did make a difference in the idle. It's smoother, but it will still die out sometimes. The SES light is always on now. I am going to disconnect the negative battery cable, to reset the computer. My question is: has anyone else had this problem after removing the catalytic converter? I appreciate any information that I can get to this post.

Thanks in advance.

dave

 

because the O2 sensor is before the cat, removing it shouldn't have any effect on it. so if u are getting a problem code saying its ur O2, then yes it need to be replaced.. oh and how much did u pay to have the shop check the code??

 

Try getting rid of the Accel stuff. Some people here have stated before that they have mysterious idle problems even with their brand new Accel cap and rotor and it all magically went away when they got rid of it. It is my personal opinion (and only that), that the Accel cap/rotor/coil is crap. I know two people personally as well as countless accounts posted here who've had problems with them.

You should start by doing some tune-up procedures like setting the timing, minimum air, TPS voltage at idle. Then check fuel pressure. Check for a failing ignition coil, clogged or clogging fuel filter. Even a clogged air filter. All the little stuff can add up to a car that doesn't run right.

Also, check on this site's technical articles section for how to pull the trouble codes and post your results here. You're in the right place, and if you're willing to ask questions, read a lot, put up with some crap, get dirty, and do some work yourself, and just plain learn, then you can get your car in top shape in a blink. When you figure out how to pull the trouble codes, you'll probably kick yourself for paying someone to do it (which is what I think breathment was about to get at..).

You don't have to disconnect the negative battery cable, just the fuse in the inline fuseholder that's bolted to the fender-area near the battery. That is the ECM/fuel pump fuse.

 

Hey, thanks for replying to my post. I think the mechanic I was telling you about was thinking about the emissions that are returned to the intake, via the catalytic converter. He also told me that G.M. makes o2 sensors for cars without cats. That part didn't make sense to me, especially since it would be illegal to operate a car without one. I'll go ahead and replace the o2 sensor and see if it helps.

The shop didn't charge me to run the code...I'm friends with one of the guys that works there, but they did charge me for some brake work they did. Pretty cool.

The only reason I bought accel parts was because I read one of the technical articles on this site that recommended accel. I had this idle problem before I put on the accel parts though. I think moving up from 7mm wires to 8mm wires was a step in the right direction.

I've only had my z about a month. I just haven't had time to do the reading on getting the codes myself, but it is something that I intend on doing.

Thanks again for the help.

dave