'91 missing and would like a second opinnion - Page 2 - ZR-1 Net Registry Forums

ZR-1Mikko · 02-03-2010

If I can get this thing running again I wont even care if you beat me

Fuel filter was changed 2 years ago. After reading "Crabs" story I'm very hesitant to just start throwing new parts at it.

bdw18_123 · 02-03-2010

Have you tried another ECM? When I lent my ECM to Tom C so he could troubleshoot his issue, it made his car run with a misfire. My ECM was bad and I didn't even know it (my Z isn't running yet). He took it to Jeffvette and it did the same thing in his car. Maybe borrow someone's ZR-1 ECM and see if it helps at all?

Demps · 02-03-2010

Sure sounds like ignition. Were the coils' resistance checked while motor was hot? I wouldn't throw parts at it but check them hot as others have had problems with non- GM coils. Problems will not always show across the coil/ wire.

Zr1 Destroyer · 02-09-2010

This sounds like the problem I had a while back.....I checked evrything and also replaced coils, injectors, sensors, fuel filter and still had a crazy miss in it at about 2500 rpm's that would stop the car in its tracks.

Soooo, I have a good buddy that happen to have an extra DIS module laying around......I swapped it and my car screamed and the miss was long gone.

Good luck....

ZR-1Mikko · 02-13-2010

Thanks guys for the tips!

I may have just found something.
Turns out my fuel pressure shakes around 45 on idle and goes down as I raise the rpm's. If I remember correctly it should be around 55?

ZR-1Mikko · 02-21-2010

Hey Ken if you are out there I wanted to see if I would be able to borrow your ecm to check if that is my problem....

kenthompson · 02-22-2010

Quote:

Originally Posted by ZR-1Mikko

Hey Ken if you are out there I wanted to see if I would be able to borrow your ecm to check if that is my problem....

PM'd you back, but this still sounds like fuel. Relay?

Glad to help if I can.

KT

kenthompson · 02-24-2010

FYI, since Mikko hasn't gotten back to this yet (more why in a sec)

We swapped the ECM out of 1790, and using the chip that Mikko had, into his car. Didn't seem to help much. Car still has a slight hesitation off idle, and runs poorly (at least according to what I remember mine running like. I.e. rip your head off at the mash of the throttle in first gear)

I thought for sure the secondaries weren't opening. Curious part was that no error codes were being generated (at least no SES light was on, even intermittantly)

I took a flashlight and verified that the secondarys did in fact work by observing them through a rapid throttle acceleration (i.e. wacking the throttle hard enough to make them react), and both sides do work.

After swapping the ECM, and listening to the car as it ran through my neighborhood, I can distinctly hear a "lean" condition when he gets on it.

So, that starts to indicate fuel problems.

We hooked up a fuel pressure gauge and achieved 50 psi at KONEOFF. Running, the pressure dropped to 42 psi. At Key off, the pressure rapidly reduced to around 20 psi, indicating a possible injector not properly seating.

Pulled the primary fuel pump fuse, and the car started and ran temporarily with the pressure rapidly reducing from 50 psi to 10 psi before the engine stalled.

I'm guessing (and suggested to Mikko) that we change the fuel filter and see if that affects the car at all. He indicated that he had recently changed the fuel pumps out.

He was going to do that later this evening after he left my house.

I'll let him carry forward with this.

KT

ZR-1Mikko · 02-24-2010

So the fuel filter is changed and still the same problem! It ran just a little bit better, but the same studder is still there through all rpm's.

Also wanted to add to Ken's description, that when the engine is warm it doesn't idle the way it used to - and makes the fly wheel to make a lot of noise.

ZR-1Mikko · 02-24-2010

I'm thinking that it must be a bad injector...which would mean my 2years old Accel's would have failed on me

The way this issue came up was:
Drove the car one day in normal city driving in good weather. No issues at this time. Parked it outside for one night. This was a Vegas winter night, which are not very cold, but little bit chilly. Went to start the car the next morning and discovered this issue. In the beginning I was able to get the car run normal for little bit sometimes by luck, but recently the studder is there at all times.

I did ohm out the injectors and they all ohm out similar cold and hot...

02-03-2010	#11
ZR-1Mikko Join Date: Dec 2005 Location: Las Vegas Posts: 108	Re: '91 missing and would like a second opinnion If I can get this thing running again I wont even care if you beat me Fuel filter was changed 2 years ago. After reading "Crabs" story I'm very hesitant to just start throwing new parts at it. __________________ If you don't put the miles on it, someone else will...

02-03-2010	#12
bdw18_123 Join Date: Apr 2009 Location: Prather, CA Posts: 809	Re: '91 missing and would like a second opinnion Have you tried another ECM? When I lent my ECM to Tom C so he could troubleshoot his issue, it made his car run with a misfire. My ECM was bad and I didn't even know it (my Z isn't running yet). He took it to Jeffvette and it did the same thing in his car. Maybe borrow someone's ZR-1 ECM and see if it helps at all? __________________ [IMG]http://i13.photobucket.com/albums/a292/bdw18_123/_zr1netforumsigphoto.jpg[/IMG][B] 1990 Corvette ZR-1 [/B][I] White/Flame Red, #2299, mostly stock, 144K miles.[/I] -Cams timed to the '93-'95 405HP LT5 stock timing. -IAT sensor relocated to below front bumper. -Haibeck hoops installed in airduct. -OBX cat-back exhaust. [COLOR=DarkRed][B](SOLD - December 2012 [/B][/COLOR][COLOR=DarkRed][B]:hello:)[/B][/COLOR] 1993 Corvette Coupe Black/Black, 6-speed (SOLD - October 2009 :hello:)

02-03-2010	#13
Demps Join Date: Jan 2006 Location: Niceville Posts: 997	Re: '91 missing and would like a second opinnion Sure sounds like ignition. Were the coils' resistance checked while motor was hot? I wouldn't throw parts at it but check them hot as others have had problems with non- GM coils. Problems will not always show across the coil/ wire.

02-09-2010	#14
Zr1 Destroyer Join Date: Oct 2005 Location: Candy Apple...yUmMy Posts: 1,137	Re: '91 missing and would like a second opinnion This sounds like the problem I had a while back.....I checked evrything and also replaced coils, injectors, sensors, fuel filter and still had a crazy miss in it at about 2500 rpm's that would stop the car in its tracks. Soooo, I have a good buddy that happen to have an extra DIS module laying around......I swapped it and my car screamed and the miss was long gone. Good luck....

02-13-2010	#15
ZR-1Mikko Join Date: Dec 2005 Location: Las Vegas Posts: 108	Re: '91 missing and would like a second opinnion Thanks guys for the tips! I may have just found something. Turns out my fuel pressure shakes around 45 on idle and goes down as I raise the rpm's. If I remember correctly it should be around 55? __________________ If you don't put the miles on it, someone else will... Last edited by ZR-1Mikko; 02-13-2010 at 11:33 PM.

02-21-2010	#16
ZR-1Mikko Join Date: Dec 2005 Location: Las Vegas Posts: 108	Re: '91 missing and would like a second opinnion Hey Ken if you are out there I wanted to see if I would be able to borrow your ecm to check if that is my problem.... __________________ If you don't put the miles on it, someone else will...

02-24-2010	#18
kenthompson Join Date: Jul 2007 Location: Las Vegas Posts: 298	Re: '91 missing and would like a second opinnion FYI, since Mikko hasn't gotten back to this yet (more why in a sec) We swapped the ECM out of 1790, and using the chip that Mikko had, into his car. Didn't seem to help much. Car still has a slight hesitation off idle, and runs poorly (at least according to what I remember mine running like. I.e. rip your head off at the mash of the throttle in first gear) I thought for sure the secondaries weren't opening. Curious part was that no error codes were being generated (at least no SES light was on, even intermittantly) I took a flashlight and verified that the secondarys did in fact work by observing them through a rapid throttle acceleration (i.e. wacking the throttle hard enough to make them react), and both sides do work. After swapping the ECM, and listening to the car as it ran through my neighborhood, I can distinctly hear a "lean" condition when he gets on it. So, that starts to indicate fuel problems. We hooked up a fuel pressure gauge and achieved 50 psi at KONEOFF. Running, the pressure dropped to 42 psi. At Key off, the pressure rapidly reduced to around 20 psi, indicating a possible injector not properly seating. Pulled the primary fuel pump fuse, and the car started and ran temporarily with the pressure rapidly reducing from 50 psi to 10 psi before the engine stalled. I'm guessing (and suggested to Mikko) that we change the fuel filter and see if that affects the car at all. He indicated that he had recently changed the fuel pumps out. He was going to do that later this evening after he left my house. I'll let him carry forward with this. KT __________________ 1990 Grey/Black Too many for the sig.