4-7 firing issue; posting for a member

[tccrab]

Ran into a problem similar to this a few years ago.
The short story is, in testing fuel injectors I had stuck my Volt Meter probe into the female sockets of the ECM plug and in doing this I had stretched out the connectors such that they didn't make good contact with the male ECM pins any more.
http://www.zr1.net/forum/showthread.php?t=10828

Maybe, just maybe, somewhere along the way somebody did something similar to your ECM plug.

'Crabs

[GOLDCYLON]

Secondary driver modules is another place to check since she is a 91?

[Tyler Townsley]

Originally Posted by Jason 91

I loved driving this car when it ran well, but this issue has been very frustrating. Mainly because I don't have the expertise to figure it out on my own and I've taken the car to local shops relying on their know-how or lack thereof.

I'm going to try another repair shop here locally and see if I can get someone to work with me through this issue. I’ll pass along your collective thoughts. And if anyone has any ideas on local places to use, please let me know. Like I said above, I just don’t have the expertise and haven't found a consistently good technician since moving to Colorado several years ago.

This has been very frustrating, as I'm sure you can imagine. Thanks for the ideas and support here.

Jason

Jason call Rod DeWild in Denver 720-284-4965 he has the expertese to help you, before moving on to LS7's he had SEVERAL 4 cam twin timing chain LT5 / ZR1 motors including a 427 cu in version running an automatic.

Tyler

[scottfab]

Originally Posted by scottfab

....snip....
I take it there is no spark at all on 4 or 7 ?

If you have spark..... yes pursue the fuel angle.
Maybe your authorized cheby dealer put the wrong injectors in?
Or otherwise did not get the connectors on right on the injectors?
Time to get dirty my friend.
Or find a friend that works the tools for you.

Bottom line is you have a ZR-1 that is ill and we want it
back on the road healthy.

[tomtom72]

I know that this is off the wall....but after an injector r&r on Jim's car, I may be wrong on who owned the car, a miss developed. It got tracked down to a pinched wire in the injector harness. I think it got pinched between the I/H and the plenum upon reassembly.......just thought I'd toss that out there.


Mr. DeWild also said the same thing about our DIS modules when I bought a spare from his stock pile of LT5 parts.....just a fwiw.



Tom

[XfireZ51]

scottfab,

I emailed a friend, whom I respect a great deal, about the DIS module.
Here is his response regarding the dead short coil

"Dominic,

The shorted coil will put a large load on the driver. Even current limited, with the coil shorted it won't take any of the load. The entire load will be in the driver which will cause it to heat up excessively."

So you were correct with your assessment although I'd still consider the likelihood to be negligible.

[Pete]

Originally Posted by Jason 91

First off, I would like to thank LGAFF for posting this up based on our conversation Saturday night. I'm the member who is having the issue and I appreciate the conversation and ideas on this.

I loved driving this car when it ran well, but this issue has been very frustrating. Mainly because I don't have the expertise to figure it out on my own and I've taken the car to local shops relying on their know-how or lack thereof.

This started awhile back when a couple of the injectors were marginal and it was suggested that I replace them which I did. The car actually ran worse after the injector change so the coil packs and spark plugs were changed at my request, but this didn't make a difference. I finally picked up the car from the guy who couldn't pinpoint the real issue.

The car was due for an emissions test and I took it in. It failed, of course, and I should have known it would have.

From here, I took it to a local Chevy dealership north of Denver which prides itself on Corvette sales and service. They quickly diagnosed it as a bad ignition module and said that they double checked everything because these can't be found.

I called Kurt at White Racing who suspected that this wasn't my issue and was thinking it was a bad ECM. So he shipped the ECM and this didn't fix the issue. He sent me the ignition module which didn't solve the issue either. Kurt accepted returns on both of these items, as a note.

When I went to pick up the car, I talked to the technician and service advisor who assured me that they checked everything possible that they could think of twice. At this point, the dealership made it clear to me that I needed to pick up my car and pay for the bill since they had my car now for over one month (due to back and forth trying new parts and locating an ignition module) and there was nothing more they could do for me until I found a good ignition module. In fairness, I'm sure that this is a standard practice given the time they had the car, but it simply added to the frustration.

I called and requested an emissions waiver on the car given what I had spent to try to get it running right and the ignition module availability. I was denied and told that this car is common and there are parts everywhere. It was even asked of me if I had tried AutoZone.

I'm going to try another repair shop here locally and see if I can get someone to work with me through this issue. I’ll pass along your collective thoughts. And if anyone has any ideas on local places to use, please let me know. Like I said above, I just don’t have the expertise and haven't found a consistently good technician since moving to Colorado several years ago.

This has been very frustrating, as I'm sure you can imagine. Thanks for the ideas and support here.

Jason

Jason,since you tried IM and ECM with no luck then i have 2 questions

Where/who's injectors did you buy/install?
I have found a few stock new injectors that were bad.
The pinched wire is also very doable.

What coils did you buy/install?
There were issues with some performance aftermarket coils.

I know it's frustrating but trust me it's something silly.
Pete

[Jason 91]

I thought that the injectors were RCs, but they actually came from Fuel Injector Connection. The coils are factory and were bought from the dealership.

#4 and #7 have no spark for certain. I was reading further through the FSM tonight (Chart C-4) and it seems like the diagnostic flow goes quickly to a faulty ignition module. I’m a novice (at best), but I can see where if someone wasn’t thorough they might jump to this faulty ignition module conclusion.
Thanks for the ideas you guys are providing here. There’s a lot to be looking for that could be simple and I really hope it is at this point.
Jason

[Jason 91]

Tyler, I also meant to mention that I reached out to Rod DeWild today and left him a message.

LGAFF, you mentioned this guy as well Saturday when we talked. I was thinking of someone else when I mentioned that I thought I knew him.

Thanks,

Jason

[ZZZZZR1]

Originally Posted by Jason 91

I thought that the injectors were RCs, but they actually came from Fuel Injector Connection. The coils are factory and were bought from the dealership.

#4 and #7 have no spark for certain. I was reading further through the FSM tonight (Chart C-4) and it seems like the diagnostic flow goes quickly to a faulty ignition module. I’m a novice (at best), but I can see where if someone wasn’t thorough they might jump to this faulty ignition module conclusion.
Thanks for the ideas you guys are providing here. There’s a lot to be looking for that could be simple and I really hope it is at this point.
Jason

Are the injectors yellow / orange? If so they are FIC's rebuilt injectors and you should test to see if they work. (rebuilt ones are known to fail too)

You should be able to see the injectors without pulling the plenum.



David