I have a 92 z with a 355 tpi, zz9 cam, 24 lb/hr injectors, vortech heads, headers, and a fast chip. Engine has been in the veh for about 5 years and havn't had any problems till recently. After the veh sat for 4 days while I was on a trip the radio got jacked and when I went to start the veh it had a very long crank time and ran poorly. After a few minutes of driving it started running ok. however over the next few days the condition became more persistant and now it runs like a three legged dog if it starts at all. First started off searching for problems and replaced the cap & rotor, spark plugs, 02 sensor, and coolant temp sensor. Veh ran ok for a few hours then when taking a lunch break it started happening again. Misfired like a timing misfire even when going 60 mph. Used a motis scan tool and had an abnormally high reading from the map sensor so I replaced that too. All other sensors read normally otherwise. replacement of the map did nothing. Attempted several other things. Unplugged all other sensors one by one, checked timing and timing chain, used old ecu chip, tested the ign module, compression tested all cylinders, performed leak down tests, pulled valve cover to check for damage, inspected wiring, buzz boxed injectors, ohm tested injectors, checked for vac leaks, plugged off egr valve, and fuel pressure checked ok with 35psi. Did have codes 15 coolant temp sensor, 21 tps curcuit, 23 iat sensor, and 43 elec spark control circuit. Any suggetsions are more than welcome.

 

Sounds like you're about where I;m at. Except mine will not start at all, and it broke down on me suddenly. Sounds like an electrical problem like mine, good luck! I can't find my problem, but I'll be watching this thread... please let us know when/if you get ir figured out.

Dave

 

Yeah, after checking what I have I'm pretty sure it is an electrical issue given that the condition was intermittent and all the mechanical components check ok. The only problem is that I have half assed wiring diagrams and connector pinouts to test the wiring that would effect it and the only other thing that would be left after the wiring is the pcm which is never a good thing.

 

After replacing many components I decided to load test all the wiring going from the ecu connectors to each sensor. I did not find any wiring issues so I decided to replace the ecu. After installation of the new ecu I found that the veh still would not start. I decided that the only stone left unturned was the distriutor even though there wasn't any real problems visualy and O wrong parts tested the ign module and said it was good. After replacement of the distibutor the veh started but ran pretty crappy and the check engine light was on for code 43 esc circuit. Further testing found that the ecu was pumping out almost 9.5 volts to the knock sensor. Installed newly purchased ecu and found that volts dropped to 4.3 volts. The veh runs now with a pretty choppy idle and running rich but at least it's running. Thinking about going to a tuning/chip burning dyno place to finally get a handle on the idle and control the fuel.

 

Try replacing the esc module?