Idle Quality Issue - Page 2 - ZR-1 Net Registry Forums

cadillac531 · 12-02-2021

Quote:

Originally Posted by A26B

Spark plug gap was revised from 0.035 to 0.050, just to improve idle.

I didn't change them to the .050, I still have them gapped at .035.

tccrab · 12-02-2021

Any ECM from any year ZR1 will work in any year ZR1.
The PROM or MEMCAL chip is year specific.

Crabs

cadillac531 · 12-02-2021

Quote:

Originally Posted by tccrab

Any ECM from any year ZR1 will work in any year ZR1.
The PROM or MEMCAL chip is year specific.

Crabs

OK, Great. That's what I thought, but figured I would double check.

cadillac531 · 12-05-2021

So about 15 years ago, I bought an LT5 that came with an ECU, well, unless something has to be done differently, this one doesn't work for the LT5. I installed the PROM and plugged in all 4 ECU connectors, but when I switch the ignition on, I get the SYS in the dash and it won't start.

I, then re-installed the PROM into the original ECU, and it starts fine. It, also seems as though my ECU issue is heat related. I started it and let it idle, and tapped on the ECU and the ignition didn't break up and die. I'm guessing there might be a solder or some element inside the ECU that is breaking down after 20-30 minutes of driving.

Are there solders or components in the ECU that are common to fix that maybe I can open it up and take a look? Has anyone had an ECU refurbished? Where is there a good shop to send the ECU to?

Thanks.

conesare2seconds · 12-05-2021

I think Marc H rebuilds them.

cadillac531 · 12-05-2021

Quote:

Originally Posted by conesare2seconds

I think Marc H rebuilds them.

OK. I also found this webpage today while doing some searching: http://www.zr1ecm.com/index.html

I'm going to contact this guy too and see what he thinks.

Thanks.

32valvZ · 12-09-2021

Are you sure the prom was seated 100 percent? I had a similar issue where when I dropped the hood I would hear the idle change a bit... I thought it was strange, but let it go.... until one day it wouldnt start at all. I opened up the ECU and one of the locks for the prom wasnt fully seated... car was fine after that. Have you had a chance to drive the car around after putting the ECM and prom back in? Just a few thoughts I had.... Good luck!

cadillac531 · 12-09-2021

Quote:

Originally Posted by 32valvZ

Are you sure the prom was seated 100 percent? I had a similar issue where when I dropped the hood I would hear the idle change a bit... I thought it was strange, but let it go.... until one day it wouldnt start at all. I opened up the ECU and one of the locks for the prom wasnt fully seated... car was fine after that. Have you had a chance to drive the car around after putting the ECM and prom back in? Just a few thoughts I had.... Good luck!

When I removed the PROM, the locks were pretty tight. I haven't had a chance to drive it around with the PROM re-installed, but that was the very thing I was planning to do next. I just have to find a day I can take it out and drive, while also having my wife waiting at home with the truck/trailer if it does die out.

I'll post up again once I have a chance to run it for about 40 minutes. That should be more than enough time for it to act up again.

12-02-2021	#12
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,654	Re: Idle Quality Issue Any ECM from any year ZR1 will work in any year ZR1. The PROM or MEMCAL chip is year specific. Crabs __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]

12-05-2021	#14
cadillac531 Join Date: Jul 2005 Posts: 243	Re: Idle Quality Issue So about 15 years ago, I bought an LT5 that came with an ECU, well, unless something has to be done differently, this one doesn't work for the LT5. I installed the PROM and plugged in all 4 ECU connectors, but when I switch the ignition on, I get the SYS in the dash and it won't start. I, then re-installed the PROM into the original ECU, and it starts fine. It, also seems as though my ECU issue is heat related. I started it and let it idle, and tapped on the ECU and the ignition didn't break up and die. I'm guessing there might be a solder or some element inside the ECU that is breaking down after 20-30 minutes of driving. Are there solders or components in the ECU that are common to fix that maybe I can open it up and take a look? Has anyone had an ECU refurbished? Where is there a good shop to send the ECU to? Thanks. __________________ Constantine Registry Founding Member #0235 1991 Corvette ZR-1 -- Stock, 94 ZR-1 exhaust system, muffler delete. 1956 Chevrolet Belair -- Pro Street, 531ci Cadillac, 8-71 Blower, 8pt roll bar, built TH-400, 9" rear, 1,100 HP -- Street Car. https://www.youtube.com/watch?v=z8y4cwcvK0s 1968 Mustang "Pegasus" -- Zeeker Chassis, 584ci Dart Block, Brodix Big Brodies, 2-1150 Dominators, FTI 'Glide, 1168 hp, best ET & Trap(holding back) 8.57@159 -- 7.9X -- 1/4 mile car. 1970 Chevelle -- 468ci, TKO600, shaved and smoothed everything.

12-05-2021	#15
conesare2seconds Join Date: Jul 2016 Location: Greater St. Louis Posts: 490	Re: Idle Quality Issue I think Marc H rebuilds them.

12-09-2021	#17
32valvZ Join Date: Nov 2007 Location: Sunshine State Posts: 1,071	Re: Idle Quality Issue Are you sure the prom was seated 100 percent? I had a similar issue where when I dropped the hood I would hear the idle change a bit... I thought it was strange, but let it go.... until one day it wouldnt start at all. I opened up the ECU and one of the locks for the prom wasnt fully seated... car was fine after that. Have you had a chance to drive the car around after putting the ECM and prom back in? Just a few thoughts I had.... Good luck! __________________ [B]1990 #2815[/B] [COLOR="Red"][B]Red/Red[/B][/COLOR] Ported Plenum & IH (by Pete) Haibeck Chip Rebuilt FPR (by Phil) FIC Injectors Watson LT Headers 3" Stainless Works exhaust Lingenfelter Open Air Lid Bill B Built Transmission Shifter & C Beam Plates [FONT=Impact][COLOR=red]1992 [COLOR=black]#[/COLOR] 091[/COLOR][/FONT] [FONT=Impact][COLOR=#ff0000]Red/[COLOR=silver]Gray[/COLOR][/COLOR][/FONT] [B]SOLD[/B]