moparman

Get the car scanned. You can look at the O2 sensors with a scan tool and see what they're doing.

Blacksmith

I also have a 93 z28. the ignition coil will cost about 15 bucks. the ignition module i haven't replaced yet. they are both easy to change. i'm also having trouble with my 93 z. right now it won't start. if i do get it started, it will run fine for a bit. but when the crap hits the fan, then it is very slow from take off (from a light for example). when it's creeping along, i'll give it gas and nothing happens but a stuttering and sputtering motion. so then i let off the gas. then it seems to clear up when i next give it gas. but then it seems to want to die out on me. once it clears that crap, then it runs fine. but once i let the car sit for a few hours, it won't start up. i'll play around with the gas cap (to make sure i'm not choking out the fuel system with lack of air). i've even released fuel from the fuel release valve under the hood to get the car started sometimes. somebody helllllllllllllllp!!!

MRBoss429x

How do I check fuel pressure. Im going to pick up a gauge. Do I attach it to the shrader valve and turn the key, but not the engine one to get fuel running, then try at WOT? Should I do this when the car is running fine or after 20 mins when its poopy? I read shoeboxs thing but need a little more help. Mine is 93 btw. THanks

Black1995Z

That would make sense.... my car just threw a code but I cant get it scanned anywhere without paying atleast $100... since its obd1 with an obd2 interface. Do you know of any shops that can scan a 95Z? Napa, autozone, oreillys, pepboys?
Last year autozone couldnt cause of the obd1 with obd2 style connector. Maybe they have better tools

84 monte SS

You dont HAVE to get it scanned. Just Swap the 02's from side to side and see if the problem follows. That will tell you if its really the 02. Its kinda obvious that its the 02 sensor being all the plugs on one side were black. If it was opti or fuel pressure the fouled plugs would be random. The 02 sensors are the only thins that control an entire side of the motor. Also if you have headers on the car and had to slpice in extentions for the 02 that maybe a connection is bad. Let me know if you figure out the problem.

Black1995Z

Well, I have one new O2 on the way, I had my drivers side head gasket blow out on me, so I was going to replace it instead. I was told the green coolant can foul O2s.
Thats why I was stumped to see the passenger side plugs all carboned up.
I will get back to you as soon as they arrive.

Kurt Crosbie

Possible clogged catalytic converter. I had the same problem and removing the cat solved it. Also could be faulty o2 sensors. That would explain why its running ****ty in closed loop.

TruDualed95Z

I'm having very similar problems and I've replaced the opti, opti harness, plugs and O2's and the problem is still persistent. I also just ordered a new set of wires that should be here the middle of next week so hopefully this will clear up the problem.

Mine has a horrible miss and the biggest problem I've noticed and everyone around me has noticed has been the ungodly backfiring/popping.

84 monte SS

Any progress?

MRBoss429x

Well fuel pressure was 39.5 with the lines primed and 37.9 at idle warmed up. Those are of the regular specs but dont know if this means its my problem. Im changing plugs/wires right now and have done the drivers side and was disappointed because the plugs/wires dont look all that bad. In fact they look pretty good so its not lookin like that was the problem.

chrism400

I would do this next. Fuel pressure is not your problem if you are in the upper 30's.

MRBoss429x

I did this when I replaced the coil. Still no improvement.

jkucz31

I didnt check but did you even to the plugs yet. my friend 05lt1 ran great for the 1st 2o minutes then warmed up and ran like **** turned out to be his wires

84 monte SS

Did you try the 02's?

MRBoss429x

plugs and wires done and car still acts like shiat. What next, ICM?