Ok got a Real good Electrical problem come on in - ZR-1 Net Registry Forums

phrogs · 01-10-2012

Ok this is on a 90 ZR-1 I know what I am checking and how to check it but not sure of what else my problem could be other than the ECM so im posting here to see what some of you think.
I also have it posted on the ZR1netregistry.

I have known for some time my #6 Cylinder has not been firing. I finally got a chance today to open it up and verify that my primary injector for sure is not firing and double check all of my wiring.

The car runs like ****, I have a tech 1 and figured out how to turn off cylinders, when I pick #6 there is no change this is just another verification that 6 is not firing.

I have newer Injectors, Replaced all plugs, wires, and coil paks I have checked everything and all ohm within specs.

Compression in #6 is good as well.

I have good spark.

#6 spark plug is clean as a whistle no carbon at all while the other spark plugs do have carbon and have been firing.

I decided to pull the plenum and do an injector spray test.

I removed all of the injectors from the Injector housing's and unplugged all of them but #6.

For this to work the Ignition module must be plugged into the harness I just pulled it off of the plenum and pluged it back into the harness.

I placed a Container under the injector to see if it sprays fuel and low and behold #6 Injector is not spraying fuel.

I also tested the #1 primary injector the same way and it sprayed no problem so I know my troubleshooting method works.

I plugged in the #4 primary injector harness into the #6 injector and it sprays when doing the same test so the injector is fine it is something electrical.

I had checked the ohms on the injectors before I pulled the plenum just to see what they were reading, all were around 14-15 ohms.

#6 was in the 14-15 ohm range so its right there with the rest of them its fine I also know from the above test that it is in working order.
That also means that my wires and conections are good from the ECM yellow plug to the #1 inj fuse. They checked out fine.

I also checked the individual wires from the # 6 injector primary plug and the wires are at .005 ohms or is it .05 ohms I had my DVM set on 200 ohms just like when checking the injectors its one of those readings. I checked the ECM to injector wire and I also checked the injector ground to the fuse and it reads the same so the wire's are good.

So no breaks in the wires that would be to easy!

I removed the female wire for the #6 injector from the Yellow weather pack plug and checked it on the ECM pin by sliding it onto the male pin as if it was in the plug it is tight with a nice drag to it and fits nicely so I do not suspect that it is not getting a conection. Then re-installed back into the yellow weather pack.

The only thing left is the ECM in my eyes.

Is it possible that the ECM could have an issue and not fire one injector?

Does anyone know how I could check that the ECM is sending a signal to the Injector? Im sure there is a tool out there for it but I do not have one

Please help I need my car running

Fire away with your thoughts I feel I have checked what I can without a Extra ECM to verify that it is not the ECM.

**Ok UPDATE**

Just got this from Marc Haibeck so if anyone has any issues with your ECM try these guys out I will be contacting them today and will update the cost and if its a rebuilt or exchanged unit.

Hi Johnny,

You did a nice job covering all of the possibilities and describing it. I agree that the most likely suspect at this point is the ECM.

I have had good experience with K & B Products for ECM repair.
http://www.kandbcorvetteproducts.com/

They have repaired 5 out of the 6 ECM's that I have sent them. On the one unit we gave up trying to fix it and they did not charge me for a repair.

Best of luck.

Marc

WB9MCW · 01-10-2012

WOW This is a good one for sure - I think you are right time to do a ECM sub.

Let's see what the others say!

ittlfly · 01-10-2012

Does anyone know how I could check that the ECM is sending a signal to the Injector? Im sure there is a tool out there for it but I do not have one.

I think you are talking about a noid light. It plugs into the harness at the injector. You crank the engine and the light flickers to show that the ECM is sending the fire pulse to the injector....Napa carries them....or any of the tool truck..ie: Snap on, Mac etc

phrogs · 01-10-2012

Quote:

Originally Posted by ittlfly

Does anyone know how I could check that the ECM is sending a signal to the Injector? Im sure there is a tool out there for it but I do not have one.

I think you are talking about a noid light. It plugs into the harness at the injector. You crank the engine and the light flickers to show that the ECM is sending the fire pulse to the injector....Napa carries them....or any of the tool truck..ie: Snap on, Mac etc

Yeah thats it!

XfireZ51 · 01-10-2012

If the wires are good, could be an injector driver. I would do an ECM swap.

phrogs · 01-10-2012

Yeah Now that I'm fresh out of ECM's

bdw18_123 · 01-11-2012

Sounds like there is a good chance it is the ECM, especially after all the extensive troubleshooting you have done already.

My '90 Z had the same issue, although the only reason I found out there was even an issue (car wasn't running then) was because I loaned my ECM to Tom (tccrabs) for troubleshooting he was doing at the time and his car ran crappy just like you describe with yours. He also took it to Jeff Flint (jeffvette) and his car ran the same crappy way with my ECM. They even swapped out PROMS and that didn't help.

So obviously it was the ECM itself that was causing the misfire (probably a bad injector driver on the board or something, I don't know. I sold it to Haibeck for the $100 he was offering for bad ZR-1 ECM's), it wasn't the original computer though, it was a rebuilt one that was put in sometime in 2001. I am now running an original ECM that I bought from sgreg back aways with the PROM that came with my car and it is running great.

Pete · 01-11-2012

Quote:

Originally Posted by XfireZ51

If the wires are good, could be an injector driver. I would do an ECM swap.

That's the only thing i can think of.
Isn't there any other Z boys by you to try one of there ECMs.

Pete

tomtom72 · 01-11-2012

I have an ECM that has a DTC 61, secondary vacuum fault code. It is an internal issue. It does let the car idle fine, it just restricts the driving rpm to 3k. I'll ship it to you as I think it would be okay as a test swap @ idle if you think it would help?

The ECM is the original one from my 90 btw. I just don't have a EPROM to put in it.

A noid light would do the same thing though.

Tom

tccrab · 01-11-2012

Johnny:

I had a similar misfire, although mine was intermittent.
http://www.zr1.net/forum/showthread....ght=probe+plug
If you've never stuck the probe from your volt meter into the ECM plug, then I wouldn't worry about it.
But if you have...............

TomC
'Crabs

01-10-2012	#2
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,607	Re: Ok got a Real good Electrical problem come on in WOW This is a good one for sure - I think you are right time to do a ECM sub. Let's see what the others say! __________________ http://i119.photobucket.com/albums/o...9mcw/SIG-2.jpg http://i119.photobucket.com/albums/o128/wb9mcw/vcm.gif "The Budget should be balanced, the Treasury should be refilled, public debt should be reduced, the arrogance of officialdom should be tempered and controlled, and the assistance to foreign lands should be curtailed, lest Rome will become bankrupt. People must again learn to work instead of living on public assistance." - Cicero, 55 BC " We the people are the rightful masters of both Congress and the courts, not to overthrow the Constitution but to overthrow the men who pervert the Constitution." - Abraham Lincoln

01-10-2012	#3
ittlfly Join Date: Jul 2009 Location: Redding Calif Posts: 223	Re: Ok got a Real good Electrical problem come on in Does anyone know how I could check that the ECM is sending a signal to the Injector? Im sure there is a tool out there for it but I do not have one. I think you are talking about a noid light. It plugs into the harness at the injector. You crank the engine and the light flickers to show that the ECM is sending the fire pulse to the injector....Napa carries them....or any of the tool truck..ie: Snap on, Mac etc __________________ 1994 ZR-1 # 0102...SOLD

01-10-2012	#5
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,669	Re: Ok got a Real good Electrical problem come on in If the wires are good, could be an injector driver. I would do an ECM swap.

01-11-2012	#7
bdw18_123 Join Date: Apr 2009 Location: Prather, CA Posts: 809	Re: Ok got a Real good Electrical problem come on in Sounds like there is a good chance it is the ECM, especially after all the extensive troubleshooting you have done already. My '90 Z had the same issue, although the only reason I found out there was even an issue (car wasn't running then) was because I loaned my ECM to Tom (tccrabs) for troubleshooting he was doing at the time and his car ran crappy just like you describe with yours. He also took it to Jeff Flint (jeffvette) and his car ran the same crappy way with my ECM. They even swapped out PROMS and that didn't help. So obviously it was the ECM itself that was causing the misfire (probably a bad injector driver on the board or something, I don't know. I sold it to Haibeck for the $100 he was offering for bad ZR-1 ECM's), it wasn't the original computer though, it was a rebuilt one that was put in sometime in 2001. I am now running an original ECM that I bought from sgreg back aways with the PROM that came with my car and it is running great. __________________ [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:)

01-11-2012	#9
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Ok got a Real good Electrical problem come on in I have an ECM that has a DTC 61, secondary vacuum fault code. It is an internal issue. It does let the car idle fine, it just restricts the driving rpm to 3k. I'll ship it to you as I think it would be okay as a test swap @ idle if you think it would help? The ECM is the original one from my 90 btw. I just don't have a EPROM to put in it. A noid light would do the same thing though. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

01-10-2012	#1
phrogs Join Date: Jul 2004 Location: Kalamazoo MI Posts: 1,744	Ok got a Real good Electrical problem come on in Ok this is on a 90 ZR-1 I know what I am checking and how to check it but not sure of what else my problem could be other than the ECM so im posting here to see what some of you think. I also have it posted on the ZR1netregistry. I have known for some time my #6 Cylinder has not been firing. I finally got a chance today to open it up and verify that my primary injector for sure is not firing and double check all of my wiring. The car runs like **, I have a tech 1 and figured out how to turn off cylinders, when I pick #6 there is no change this is just another verification that 6 is not firing. I have newer Injectors, Replaced all plugs, wires, and coil paks I have checked everything and all ohm within specs. Compression in #6 is good as well. I have good spark. #6 spark plug is clean as a whistle no carbon at all while the other spark plugs do have carbon and have been firing. I decided to pull the plenum and do an injector spray test. I removed all of the injectors from the Injector housing's and unplugged all of them but #6. For this to work the Ignition module must be plugged into the harness I just pulled it off of the plenum and pluged it back into the harness. I placed a Container under the injector to see if it sprays fuel and low and behold #6 Injector is not spraying fuel. I also tested the #1 primary injector the same way and it sprayed no problem so I know my troubleshooting method works. I plugged in the #4 primary injector harness into the #6 injector and it sprays when doing the same test so the injector is fine it is something electrical. I had checked the ohms on the injectors before I pulled the plenum just to see what they were reading, all were around 14-15 ohms. #6 was in the 14-15 ohm range so its right there with the rest of them its fine I also know from the above test that it is in working order. That also means that my wires and conections are good from the ECM yellow plug to the #1 inj fuse. They checked out fine. I also checked the individual wires from the # 6 injector primary plug and the wires are at .005 ohms or is it .05 ohms I had my DVM set on 200 ohms just like when checking the injectors its one of those readings. I checked the ECM to injector wire and I also checked the injector ground to the fuse and it reads the same so the wire's are good. So no breaks in the wires that would be to easy! I removed the female wire for the #6 injector from the Yellow weather pack plug and checked it on the ECM pin by sliding it onto the male pin as if it was in the plug it is tight with a nice drag to it and fits nicely so I do not suspect that it is not getting a conection. Then re-installed back into the yellow weather pack. The only thing left is the ECM in my eyes. Is it possible that the ECM could have an issue and not fire one injector? Does anyone know how I could check that the ECM is sending a signal to the Injector? Im sure there is a tool out there for it but I do not have one Please help I need my car running Fire away with your thoughts I feel I have checked what I can without a Extra ECM to verify that it is not the ECM. Ok UPDATE** Just got this from Marc Haibeck so if anyone has any issues with your ECM try these guys out I will be contacting them today and will update the cost and if its a rebuilt or exchanged unit. Hi Johnny, You did a nice job covering all of the possibilities and describing it. I agree that the most likely suspect at this point is the ECM. I have had good experience with K & B Products for ECM repair. http://www.kandbcorvetteproducts.com/ They have repaired 5 out of the 6 ECM's that I have sent them. On the one unit we gave up trying to fix it and they did not charge me for a repair. Best of luck. Marc __________________ JOHNNY P Currently own 90 ZR-1 #845 DRM 500 engine package 90 #226 Parts car Hit me up if you need anything. Last edited by phrogs; 01-13-2012 at 01:50 PM.

01-11-2012	#10
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,645	Re: Ok got a Real good Electrical problem come on in Johnny: I had a similar misfire, although mine was intermittent. http://www.zr1.net/forum/showthread....ght=probe+plug If you've never stuck the probe from your volt meter into the ECM plug, then I wouldn't worry about it. But if you have............... TomC 'Crabs __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]