ninetythreez

My 93 Z28 is idling low and erratic. It has a tendensy to try to cut off when I press the throttle also. I removed and cleaned the throttle body. I installed a new Throttle Position sensor and cleaned the old IAC valve(may need a new IAC Valve??). I checked all my vacuum hoses and the 2 PCV valves also. Could it be my spark plugs? My car sat for 2 months not being cranked while I was away also...Help

hsyr

My car had similar problems. Rough idle, would sometimes stall out. Backfire occasionally. Then when I would go WOT the whole car would just cutout. Is your SES light coming on? Mine did and I got DTC 36. Ended up being that my opti was shot. Get it scanned first that way you have a good idea.

ninetythreez

I have a spare opti. Are they really hard to replace? I hope the opti I have is for a 93-94. How do you tell the difference in the 93 and other optis? I have already replaced everything except my IAC valve. I have a new TP snsr, coil, ICM,Air temp sensor, plug wires. I have not replaced my rear cylinder plugs yet. I have 6 of the 8 installed already. I don't think 2 bad plugs would cause my car to run this way. Someone help me on the OPTI I.D. please!!

LT1Squirrel

do you have an SES light?

ninetythreez

yes but i also have a no restriction exhaust that probably makes my o2 sensors light up all along..It ran great before I let it sit for 2 months...

Fastbird93

First, FIND OUT WHAT CODE IS CAUSING THE SES LIGHT TO COME ON. Use the procedure shown HERE to flash the codes (Thanks Shoebox for the reference pic).

Whatever code comes up, there's a link in my sig with direct scans from a 93 Service Manual for ALL the DTC's for the 93 model year.

Don't just start throwing parts at your car without first using the obvious clues (SES light being on) to figure out what is wrong. It's a waste of time, and more often than not ends up being a waste of money too.

MentalCaseOne

Yes. Number one spark plug's insulator craked by the electrode. a Very fine hairline crack from the tip down and into the spark plug itself. Dude I was rushing to buy a new opty cause the car felt like it was a preggo girl with morning sickness!! it was exhaust popping too. Shaking like a druggie on a 10 day Acid Diet. Totally un-cool.

I guess all that oxygen in the exhaust was making all that bank run rich and misfiring on the other cylinders too. I dont know but it was bad.


Marvin

ninetythreez

OK. I have a fuel pressure problem. New Walbro pump 2 months ago. Less than 50 miles on it. makes a sound like it flushes pressure off of it after it motors up. I can hear it in the tank as it is the electric motor pessures up and then you can hear the pressure flush out as the gauge also looses pressure from 20 lbs and then suddenly back to 0! I am gonna check fittings on my pump...