Well, I have been chasing this problem for almost a month! Last month, I had a valve ticking. I replaced my rocker arm nut and then put my valve cover back on. I did not realize, but my ignition wire was pinched under the valve cover, wires are really tight back there! So, I had a major short. so, I fixed that problem. Over the past two weeks, I noticed my car was running terrible under a load @ WOT. Now, the car will only idle for 30 seconds and it sounds like it's running on 5 cylinders Here is what I have done;

fuel pressure regulator; inspected it and it holds 43.5 psi. With the key on, engine off, the fuel pressure holds. Once I turn the key off, my fuel psi drops to 30 psi in 30 seconds, and to zero in about 10-15 minutes. I think this is normal. I suspected a fuel injector problem possibly. fuel injectors read 14.7 ohms (ford svo 30's). Pulled out the fuel rail and they seem to work fine.

My plugs are black, which is normal due to supercharger and I run my tune a little fat till I have time to get her on a dyno.

spark; I changed my ignition module, coil, map sensor (all parts I have left over from my 91 Vette which also had the 7730 ecm). No change? Car still runs like

One thing I do notice is that with the engine off I can see my voltage in my CM software and laptop is my tps sensor is working fine. However, my MAP sensor is reading 4.8volts. I pluged in my other map sensor which I know is good and it reads the same 4.8volts. I pluged in my two bar map sensor for my timing control I use with my supercharger. I get 2.33 volts. I have changed my plugs, gapped then @ .035, cap and rotor....Nothing?????
I get no codes, just the code 12 = no codes?

HELP before I repair this car with my SLEDGE HAMMER

 

i would change the plugs and see how that helped. if there are black there probably fouled and some could not be fireing. its a good place to start.

 

I changed my plugs wtth no results. I have completely replaced all ignition components. Plugs, wires, coil, ignition module, cap/rotor, coil.

 

Just going to throw this out there, but chased a similar
problem with mine.:

Everything checked out fine as to trouble shooting electrical, mechanical and could'nt figure it out.
Had changed everything out as to relays, most sensors
because of age of car,20 years.

Had also changed out the coolant temp sensor,( ECM Controlled). After reading up on problem decided to try
another new sensor and BINGO, no more problems

Just a thought

Later

 

I have a duplicate of pretty much every sensor including my map sensor with no results. I found my electrical problem. Burned out brake light and I replaced it with a one wire filliment bulb I had for my mazda truck I replaced the bulb....then I had to RE_ASSEMBLE MY DASH all over a two filliment bulb.

It still does not idle for crap.

What can cause a car not to idle.

Fuel; I have fuel, my plugs are black. I wonder if my fuel injectors are bad? I turn the key on and my fuel psi goes to 43, then drops to 30, then 20 in a matter of 15 minutes. fuel psi regulator has no holes in it upon inspection.

spark; I have spark

Air; vacume leaks

 

Oxy Sensor?? Fouled.
How old are the injectors, leaking?
My AFPR holds pressure alot longer than that.
Could be leaking and fouling plugs on startup.
ECM coolant sensor? again
Vacumm leak, Ecm compensating as to AFR?
But thats OL if cold and CL if warmed up.

Did this problem just start or like this from git go?
Just some ideas

Later

 

I have an extra O2 sensor and no change there. I don't think it's a vacume leak as my idle does not rev up high. It seems to run OK when it's cold...for about 10 seconds, then it really runs like poop and dies within 30-40 seconds. I had an electrical issue which turned out being a bad tail light I thought it was an electrical issue till I fixed that problem.

What or how it started was I was driving and I noticed my car was running like poop @ WOT. My car seemed to run OK during cruise, but @ WOT, it was as if it was not geting enough air or too much fuel and just bogging way down. Once I got it home, it hardly idles anymore??? I'm thinking leaking fuel injectors but not sure. plugs are black, but I run rich due to larger injectors and having a supercharged car, rich = a little more safer and room for error.



How to check for leaking or bad injectors? I figured if they were leaking, my car would try and run lean via the ECM. When I do get my car to idle and I raise the rpms, I can tell it's running pig rich. I have a black spot where the exahust dumps out of my Z.