STILL NO SPARK ON TWO CYLINDERS

[SDZR-1]

Before I disassembled my top end for a starter and injector replacement I had checked for spark to all cylinders...everything was good. While my plenum was off, I decided to change wires and plugs. After reassembly the car was still running a bit rough, but it was definately a different rough than prior to injector replacement. After checking for spark I determined that cylinders 2 and 5 had no spark to the plug. I figured the only logical explanation for this was that I had a bad coil, so pulled everything apart to install coilpacks when I discovered that 2 and 5 werent even on the same coil and was a little confused....but I put it back together still hoping that it was more than one coil or something of the sort. I was sadly disappointed when it sounded no different than prior to coil replacement and cylinders 2 & 5 still had no spark....I am very very frustrated at this point (and trying to hold my temper back and used it on someone who deserves it...haha) because now I am looking at doing a 3rd plenum pull to figure this all out. The only other idea I have is that the plane that the coils mount to has shorted out....but dammit, I want to be sure this time so was hoping someone had somewhat of a similar experience. So if this is what my problem is....how much more cash am i gonna have to shell out, this is getting rediculous...what a way for a zr-1 to welcome it's new owner.....I guess it ran well for my 1500 mile journey home, so at least I didnt experience these probs on the road.

thanks,
Jarvis

[guinnessdood]

Jarvis,

Have you checked the new wires for proper resistance? Maybe you got some bad wires? Or more likely some bad ends on the wires...check them out. Are you certain that it's NO spark and not NO Fuel? If the connector on the injector is not all the way on...no fuel. What wires/plugs/injectors did you buy? Right now I am betting on the injector connectors. I had one that was not all the way on when I changed my injectors (Accel) (ran like crap on 7 cylinders)...I was able to get to it with a flathead screwdriver and push it the rest of the way on. If you bought Accell or MSD injectors the nub on the primary injectors need to be ground off to get the connector to fit properly.

[SDZR-1]

Originally Posted by guinnessdood

Jarvis,

Have you checked the new wires for proper resistance? Maybe you got some bad wires? Or more likely some bad ends on the wires...check them out. Are you certain that it's NO spark and not NO Fuel? If the connector on the injector is not all the way on...no fuel. What wires/plugs/injectors did you buy? Right now I am betting on the injector connectors. I had one that was not all the way on...I was able to get to it with a flathead screwdriver and push it the rest of the way on. If you bought Accell or MSD injectors the nub on the primary injectors need to be ground off to get the connector to fit properly.

No...havent check wires for resistance...but thought it would be odd to have two at once since they were new. I installed accel injectors, delco wires and plugs. There was no spark going through either wire when I pulled them off I heard no spark and also no spark to a screwdriver when placed near the wires end. Also, I did grind the nub off of the primary injectors. I am pretty certain that all of the connectors went on all the way because i specifically listened for each of them to click when the wire holder fell into place on the injector. thanks for the quick reply.

[guinnessdood]

Originally Posted by SDZR-1

No...havent check wires for resistance...but thought it would be odd to have two at once since they were new. I installed accel injectors, delco wires and plugs. There was no spark going through either wire when I pulled them off I heard no spark and also no spark to a screwdriver when placed near the wires end. Also, I did grind the nub off of the primary injectors. I am pretty certain that all of the connectors went on all the way because i specifically listened for each of them to click when the wire holder fell into place on the injector. thanks for the quick reply.

Jarvis,

Do you have a Factory Service Manual? http://www.helminc.com/helm/Result.a...H2AE6VM2S42BJ4

If not...you should get one from the link above or on eBay. Best money you will spend on your Z. Make sure you check all of the things I mentioned and hit us back....we'll get it figured out...can't be anything too serious. You could always try swapping coil packs around too...see if it changes cylinders. I know that removing and replacing the plenum gets old...just gotta have patience. BTW...if you do the throttle body coolant bypass that saves some time and hassle. Do you drain your coolant resivoir? That helps too. I am speaking about making the plenum pull a little easier. Are you plenum gaskets in good shape? Hope so...they're not too cheap.

OK, I'm going to get on a soap box here.

We have a lot of guys who are pretty bright, know their way around a LT5 and can help troubleshoot a car over a vast distance, which is fairly difficult. The only bad thing is when the owner of the car does not fill us in on what has been changed or been found. Had you mentioned the plugs on 5 & 2 where the suspect coils, we could have told you they were not a grouped pair. You did not make any mention of brand new plug wires in your previous posting.

I will add this, the grounding plane is not a high failure rate part. I have only come across it once. If it is bad, I have a spare part that you can borrow, as it is no longer available from GM. But cylinders 5 & 2 do share a common connector going from the DIS to the ground plane. Dark Green and yellow wire coming out of the DIS connector.

[tccrab]

Sounds suspiciously like the problem that I had last year after I replaced my fuel injectors.....
http://www.zr1netregistry.com/forum/...ead.php?t=2206

Good luck!

[SDZR-1]

Originally Posted by Jeffvette

Dark Green and yellow wire coming out of the DIS connector.

Are you referring to this as a single wire that is colored dark green/yellow....or as two different wires (1 green, 1 yellow)?

[SDZR-1]

Originally Posted by tccrab

Sounds suspiciously like the problem that I had last year after I replaced my fuel injectors.....
http://www.zr1netregistry.com/forum/...ead.php?t=2206

Good luck!

Well as luck would have it, there are 4 other zr-1's in my tiny little town of 350 ppl. I bet I could borrow an ecm just to determine if that is my problem. 3 of these are sitting in our shop, but the '91 isnt as easy to access as it is in the trailer...is a 90 ecm the same, or should I be certain to try to 91?

Oh, mine's a 91 btw.

Thanks everyone,

Jarvis

[guinnessdood]

Originally Posted by SDZR-1

Well as luck would have it, there are 4 other zr-1's in my tiny little town of 350 ppl. I bet I could borrow an ecm just to determine if that is my problem. 3 of these are sitting in our shop, but the '91 isnt as easy to access as it is in the trailer...is a 90 ecm the same, or should I be certain to try to 91?

Oh, mine's a 91 btw.

Thanks everyone,

Jarvis

Jarvis,

Jeff was referring to ONE single wire. You can swap in the 90 ECM...but you need to swap in your 91 PROM into the 90 ECM. There is a plate on the bottom of the ECM with a bunch of small screws. Take off the plate and there sits your PROM. Don't try the 90 ECM without swapping in your 91 PROM...they are different.

[Kevin]

Stupid question, how did you determine you didn't have spark?