Re: Crank No-Start/Idle 91 ZR-1
 

Your symptoms sound the same as mine, that I have overcome in the last couple of days. I thought my Cam Sensor was ok BUT upon advice from Marc, I disconnected the wiring harness from the Cam Sensor to the ECM. Engine fired up and ran straight away. Put another Cam Sensor in ( borrowed secondhand) and car is back to normal.
Hope this works for you 🤔

Cheers,
Russell 🇦🇺

Re: Crank No-Start/Idle 91 ZR-1
 

I read your thread right after I posted my latest update. I was skeptical that it would work mainly due to not having any injector pulse. I still ran out and tried it immediately. Unfortunately no workie. Thank you for looking out!!!

Re: Crank No-Start/Idle 91 ZR-1
 

Hi Baggy,

even if your tests results highly suggest that you have a faulty ECM, would you have a ZR-1 friend around to perform a swap test to finally confirm it ?

If not, I guess the cheapest option at the moment is to use your warrantly. The technician who performed repair should be able to confirm the failure by placing your ECM in its own test car and then investigate if the failure is related to the rework or something new.

I do not see ECM for sale on Ebay or corvette forum so far.

Re: Crank No-Start/Idle 91 ZR-1
 

Howdy everyone, I would like to post the fix and round out this thread. We received the ECM back from rebuilder on 12/4 and installed it on 12/5. Vehicle started and ran like a top! Rebuilder said that some solder bridges on the original boards were cracked, some broken, and were missed on the original inspection.

Thank you all for your help, knowledge and support. Learning a new system and diagnosing it has added another feather to my cap. I wish you all a Merry Christmas, Happy Holidays, and a great 2025!!

:saluting:

Re: Crank No-Start/Idle 91 ZR-1
 

Glad to hear that you?re back up and running again Baggy.

Cheers, and Merry Christmas from down under.
Russell 🇦🇺

Re: Crank No-Start/Idle 91 ZR-1
 

Good to know there may be a vendor for restoring ECMs.

Re: Crank No-Start/Idle 91 ZR-1
 

Sounds like zr1ecm.com (Macroblock) can fix ZR1 ECMs :thumbsup::thumbsup:

ECMs with some solder bridges on the original boards cracked, and some broken.

Re: Crank No-Start/Idle 91 ZR-1
 

What did they charge to repair your ECM? What was the turnaround time?

Re: Crank No-Start/Idle 91 ZR-1
 

I can confirm, I have been able to repair almost every C4 Corvette ZR1 ECM I've worked on. The few that are not repairable I strip for parts.

Based on the numbers, there are 10-15 ECM failures per year. Of the ones I've worked on, IC's U13, U15 and U4 are the most troublesome.

Baggy Toaster's ECM had a defective U13. In this instance I was forced to substitute his defective U13 with a discrete outboard microcontroller to perform the functions of this IC.

The difficulty with these ZR1 ECM repairs comes from lack of parts. There are none. More often than not, I am forced to invent a workaround for an ECM's specific failure. This is very time consuming.

Fortunately, I have a hardware and software background in electronics, so I was able to create a bench-top ZR1 ECM emulator, which provides much faster diagnostics than testing on-car.

My work comes with a 2-year warranty.