nophix

My '94 z28 has been running great since a massive amount of maintenance in August. Head gaskets, Delco Opti, full tune up, blah lah..


Recently with the cold weather, it has this random die problem. Sometimes it fires back up, sometimes it doesn't for quite a while.

Here's what I've found. All injectors ohm out to 13-13.6. 12 volt at rails on all connectors. Fuel pressure is well in spec, verified with a gauge. Has spark. When it dies, I can fire it off Ether, it will run for a few seconds.

The car will run fine for days, then just randomly goes through these retard streaks. I drive 140 miles a day for work, all interstate.

Battery, alternator are new, all connections have been checked and cleaned.

Somewhere this thing is losing injector pulse width.

It is popping a code 18-injector circuits. The question is why? I'm lost. This is my daily driver right now thanks to the lovely Wisconsin deer, and my new one won't be here until January.

Injuneer

It's telling you the injector circuits are not as secure as you seem to feel. There is at least an intermittent failure of one circuit, maybe more. Could be an issue with an injector driver in the PCM. One injector would not shut down the engine.

And you are sure there are no other codes... DTC 16 would indicate an intermittent failure of the low resolution cam position signal from the Opti, and when that sets, the PCM shuts down the fuel system. DTC 16 does not turn on the SES light, so it's a code that often gets missed. Is it possible you have a damaged "short" Opti harness, with bare wires, or corroded or bent connector pins?

Have you done a scan to verify that the PCM is zeroing out the pulse width when it shuts down? Do you have a data log showing a failure?

https://www.camaroz28.com/forums/com...95-lt1-874306/

nophix

I just ran it out again, and I did in fact get a code 16. I'm using the Scan 9495 software.

I forgot to save the log when I shut down my laptop. But doest the low res circuit also control spark reference? I was under the assumption that if that failed, I'd lose spark as well. I get spark right away, but no injector pulse.

I was able to restart right away after the code cleared, though.

Injuneer

The PCM uses the low resolution signal to time the injectors and the spark. The factory manual (I only have 94 and 96, not 95) indicates fuel pump and injectors are disabled. Does not mention spark.