My '93 Z28 hasn't always has a rough idle, moreso lately than ever before. It usually only happens coming up to a stop light/sign when the car is in drive with the brakes applied. Last winter I had replaced the opti cap + rotor, GM ICM, NGK plugs, wires and a GM coil and it has ran great since then. Yesterday my fiance and I were pulling up to a house and stopped the car, while still in drive to check it out, and the car sputtered and died. Tried starting once and it just cranked, but on the second attempt it fired up just fine.

No codes have been stored, I tried pulling them with a paper clip. I checked fuel pressure this morning: 35psi at idle with vacuum line connected, 44psi with line disconnected, and it dropped to 28psi and held steady there after shutting it off. My gauge doesn't have a long enough hose to test run while monitoring it, but I'll try to get ahold of one. Any suggestions? Mods are in sig.

edit: Car has 129,XXX miles, and is running fine otherwise. May be a slight misfire at partial throttle but very hard to tell.

 

Kinda of the same problem as mine, only I actually have a misfire. Putting in new plugs and wires in a week. As far as your problem goes, sounds like maybe your fuel pump is starting to act intermittent. I would keep an eye on it and see if it gets worse when warm, etc etc.

And you're sure the paper clip trick worked?

 

I would clean the idle air control passages. (IAC)

 

Fast - Yep, I've pulled codes numerous times with this car. It blinks a series of lights if no codes are stored.

Joe - I'll give that a try, haven't touched that yet. Anything in particular work for that? Brake cleaner? Alcohol? Electric parts cleaner?

I just stopped at the store to pick up new plugs and a fuel filter just to be sure. When I have all the plugs pulled I'm going to do a compression check; most likely not related to this issue but will be good to know.

 

Good stuff, let us know how that turns out! Good luck!

 

After first 25-30 minutes I found #7 spark plug wire burned, not sure if it would cause this or not but it needs addressed. I pulled the A/C while I was in there today, woo!

 

Yeah, I would definitely replace it. Particularly if it is cracked or severely damaged. If you can afford it. Replace them all so they all have the same resistance, etc.

Nice job on the A/C.

 

I was going to say Fuel Pump or Fuel Filter, but yea replace the plugs!

 

After getting Mexican with the fiance and getting some groceries I pulled the rest of the A/C out sans the box on the firewall. I didn't get to the compression check, but I'm going to order Taylor's OTVC kit. I had good luck with it on my last Z, as well as the Taylor fire sleeves. So when that comes in I'll do the comp. check. Plugs did look okay, each with just a slight whitish ash covering, no carbon buildup or anything. All still gapped at .050, but they did only have ~10k on them. Time to take it for a spin!

Anyone have a 1LE A/C delete pulley for sale?