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

01-10-2012	#1
phrogs Join Date: Jul 2004 Location: Kalamazoo MI Posts: 1,753	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 02:50 PM.