Miss that is developing? (Help)

[TFENT]

Originally Posted by Paul Workman

One crisis at a time, I recon!

First, that fuel pressure thing needs to be resolved. Sounds like a new regulator is in order.
Second, you might either clean and install or buy some standard (AC Delco) plugs and begin again with a fresh, clean set. Then we can go from there.

FWIW, with the fuel pressure all over the map, the fuel flow is too, and the ECM and O2s are not able to provide accurate fueling information - mostly rich, is my guess, which will foul the plugs to the point it may well be a subset of your starting problem.

Just my 2 cents.

P.

Paul:

Your 2 cents is worth it my friend.

Just to clarify.

Plugs:
The plugs are brand new after the sooty ones were removed, maybe 10 miles on them.

FP Readings:
Normal at part throttle very steady, varies with load 38-55psi. Then vibrates excessively under WOT 48-60+ psi. Hard to tell how high/low it goes as u can barely see the needle its moving so fast.

No Start:
If you let the car sit all night and go to crank it it starts just fine no prob. If you turn it right off and try it again it's a 50/50 shot it will start back up. Again if you let it sit for hours it will start right back up no prob. FP readings are normal. 45-50psi and slowly leaks down to 30's after 10 mins or so.

[tomtom72]

Okay Tom. Your call as yours is a 90 also. I can ship you the ECM with the AUAH Prom installed or with out the PROM installed. Just say the word and I'll get to it.


Tom

Done deal! shipped via USPS Express Mail. Tom you have a PM with the tracking number!

[TFENT]

Update 9-20

Thanks to Tom I received a spare ECM to try in the car. For the last several days the car has refused to start, as stated before it had fuel pressure and spark. After it once again refused to start today we immediately swapped out the ECM and cranked her over. She started right up and at first back fire a bit then smoothed right out and never miss fired after letting it sit there for several minutes. Then once it was a little warmed up I juiced it a bit. Again it back fired at first and then was quick to react to the throttle response. VERY quick to respond to it actually. I believe the back firing is from all the gas in some cylinders that were not working properly and it being cleaned out. No i am not going to jump on a limb here and say it's cured for fear of jinxing myself. But initially it seam to be much smoother of an idle and it's running and responding "normal". The real test will be after a few days of seeing if she wants to start "on command" and then taking her out for a few WOT runs to see if we get any codes. If at that point she performs as designed I will know I had several issues and one being an ECM that didn't want to accurately work all the time.

I will keep you all posted.

BTW Tom sent me this ECM overnight express mail and wouldn't let me pay for it. Man what a BROTHER!!!

[tccrab]

Originally Posted by TFENT

Update 9-20

BTW Tom sent me this ECM overnight express mail and wouldn't let me pay for it. Man what a BROTHER!!!

The Brotherhood Of The Beast is ALIVE AND WELL!!!

TomTom72, U Da Man!!

TomC
'Crabs

[tomtom72]

Tom, I'm glad that there seems to be some sort of help with the ECM. I just question if it is the ECM or the EPROM. Sorry for sticking my two cents in on this issue.

How many cold solder joints could one of our ECM's have, or is it likely that our ECM's could have gizmos become intermittent on the main board?

Or, is it more likely that cold solder and bad/intermittent gizmos could happen to our EPROMS?

Humor me, just swap out EPROMS, take mine and put it in your ECM and let's see what transpires?

Just tossing this out there as a fwiw. Lord knows I'm not an electronics wiz-kid, word!

Oh, take your time with this trouble shooting. No need to waste any money on parts till you are satisfied with your diagnostics. Soooo, keep the ECM for as long as you feel is needed to run this issue down to ground!


Tom

[TFENT]

Tom:

I can't thank you enough... I can see the light at the end of the tunnel now and feel like we took a huge step in figuring this thing out.

I will definitely swap out the PROM's and try them out. Good suggestion.

But if I do need a new PCM/ECU where do I get one?? Suggestions?

[tomtom72]

Okay Tom, I found a place....I can't remember where I ran across him. I think it was over at the other ZR-1 section at the other corvette forum...I think.

Anyway I was going to send him my original ECM, it took a dump on me awhile back with a DTC61...grounding issue I think on that circuit?

Link: http://gmautocomputers.com/
I was going to call them first to see if I could get a sense of their confidence level in working a ZR-1's ECM. Their site says that they can fix them all.

The only other suggestion I can offer up is either corvette recycling, Les Stanford Chevrolet(?), or partszoneonline.com is where I got my spare ECM five yrs ago.


Tom