My injector drivers produce ground to 2 of 8 injectors for about 1 minute then come on as if someone flipped a switch. I have professionally determined that the PCM is faulty by checking all other potential trouble. Has anyone else experienced this? Exchange PCM's are hard to find and mine will have to be repaired via R&R to Cardone. Does anyone have a good one to sell?

 

What year is the car?

The injector driver circuits changed a LOT over the years, from batch fire to sequential fire. It's very important to know what the year is.

 

My car is a 95 lt1 coupe i should have included that in my post ! Rookie mistake

 

I recommend getting a noid light and checking all the injector connectors. That should help narrow down the problem.

 

I own an auto repair shop. I am very hesitant to replace computers unless my techs can absolutely prove there is a problem with one. The injectors all ohm out to specs and connections are good the problem is lack of ground signal from the computer for about a minute. The grounds then come on and the car runs fine. Availability of reman or used computers is zip. I think my only bet is to send mine in for rebuild. I still have that feeling I may be missing something so I reached out to the Vette community to see if this has happened to anyone else

 

That sounds like an intermittent ground problem.

The ground needs to be there between the PCM and the engine block. There might be a bad battery cable ground connection to the engine block. It should be above the oil filter on the side of the block (unless they moved it for LT1s). I don't know how the PCM is grounded to the engine on LT1s. On early L98s they used the same bolt as the negative battery cable. Later L98s used a stud on the bell housing.

It could also be a problem in the PCM connectors, like corroded pins. That is not really likely if ALL the injectors stop working at the same time. The common connection is the ground, so it still might be a corroded ground pin in a PCM connector. You said all the connections to the PCM are good. Did you verify that with an ohmmeter? One problem with intermittents is that you might happen to be measuring when they are OK. Wiggling connectors and wires should help bring out problems.

 

Thanks for good ideas have visited all possible grounds and pins and they appear good i will recheck before last resort of pcm replacement

 

Have you checked both the pins & sockets pluging into the PCM for corrosion?

 

The C4 wire harness is notoriously fragile and subject to insulation cracking and breakage over the years. there are also so VERY cheesy splices in the harness where the grounds are attached.

One extremely weak point is behind the wiper motor. The trunk line on the firewall has several ground wires that are clipped onto the trunk line ground in the main harness. Then the only protection is a wrap of black tape. The GM vendor was obviously the low bidder for the harness....

grab and wiggle THAT area of the main harness that's on the firewall at the wiper motor. This is where the 5 grounds come from that attach to the block by the oil filter,. and the attachment is WEAK at best.

Next you should do the wiggle test on the injector harness section. I had to chop out the entire driver side of the in j harness and solder in new wire. It was all cracked and cross signaling under the conduit sleeve. The passenger side looked like new....go figer?

It may come down to a bad PCm but finding a replacement should not be that hard. It might end up being a used unit,. but that's damn sure better than no unit !

Look at FleaBay for LOTS of used PCMs that often come with some form of warranty.

Good luck

a couple options :

http://www.ebay.com/itm/Chevrolet-ECM-ECU-PCM-Engine-Computer-Repair-Return-Service-/221558581044?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1995%7CModel%3ACorvette&hash=item3395eba734&vxp=mtr


http://www.ebay.com/itm/NEW-VIN-PROGRAMMED-94-95-ECM-PCM-ECU-Corvette-Engine-Computer-16181333-88961148-/400807039157?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1995%7CModel%3ACorvette&hash=item5d51f610b5&vxp=mtr