Intermittent SES Light

[VetteMed]

Injectors can tick, especially if stuck...

[tomtom72]

The area you say the "tick" is coming from is where the coil rack is located, and quite a few other electrical connections as the DIS box connections are also in the same location.

Andrew is also correct in that the pintel type injectors do make a distinct "ticking" noise sort of like what solid lifter old school small block chevys used to sound like at idle.

I'm puzzled by the different set of DTC's that autozone retrieved. Or maybe I missed something here?

we don't have a DTC 35 in the LT5 library? The rest are consistent with what you listed in the original post.

I know this isn't much diagnostic help. I just wanted to post a response to you so that you would not think no one is listening. Let me go back to the FSM and I'll post up after I think about this a bit! I hope Dom or Pete see this and post up.....that's better than me doing this!


Tom

[tomtom72]

Okay:

23 = low intake air temp. will set if no VSS signal but motor running more than 2 minutes. Or ignition on motor off ( as in just scanning for stored DTC ) coolant temps greater than 86* Check the connection at IAT & ECM is my best guess or bad wiring.

35 = doesn't exist for an LT5

46 = VATS system fault. I don't get this one. It seems that two way serial data communication between the CCM & ECM is snafued some where, wiring issue or ground issue most likely as you have the correct key.

62 = oil temp above 286* try resetting the oil life monitor is what I get out of the diagnostic aids. It's that or the wiring is snafued again!

Something strange going on here. Not much of these DTC's make any sense. Unless the ECM is out to lunch? You don't have access to a know good ECM just to swap in to see what happens with all these DTC's?

Don, you don't have your own scanner, right? Throwing parts at this issue is not a good idea. Do you know anyone that is near you that has a scanner with our software so you can do the scan. Do you have a fuel pressure gauge? I'd do the F/P test just to eliminate that side of this equation one way or the other. After that I'd move on to ignition, then finally to start checking all the wiring at the indicated malfunctioning sensors. Sorry man that's all I can come up with, not much I know!


Tom

[c4zr1]

I do not have my own scanner. Thinking about buying one though. I do have a pretty repupable shop I take other stuff too. When you say someone with a scanner with our software. What does that mean? What should I ask the shop guy about what software he has? I can probably come up with the Fuel Pressure switch to check the FP's out.
I do appreciate the feedback from everyone up to this point.
On my ECM I did get it rebuilt, but I may have someone here in town I can borrow a 91 ECM from.

Thanks!
Don

[ScottZ95ZR1]

Originally Posted by c4zr1

IOn my ECM I did get it rebuilt, but I may have someone here in town I can borrow a 91 ECM from.

Thanks!
Don

Hi Don!

While your ECM was out for rebuild you had my spare. Did you drive the car enough then to be confident it fixed your issues - I mean are the issues you're seeing since swapping back to your rebuilt computer the same as before ?

[scottfab]

I think you'll find having your own scanner to be $ well spent.

[c4zr1]

Hi Scott!

I does seem to have the same issues as before. I drove the car very little while I had your ecm. I probably did not drive it enough to really know it was the ecm like I thought. The ecm might not have been the real problem.

Don

[ScottZ95ZR1]

Originally Posted by c4zr1

Hi Scott!

I does seem to have the same issues as before. I drove the car very little while I had your ecm. I probably did not drive it enough to really know it was the ecm like I thought. The ecm might not have been the real problem.

Don

I ask only because I recall reading at least one thread where someone had their ECM remanufactured to find it was still faulty. Hopefully that is not the case here.

I know Marc Haibeck has had success having them repaired - hopefully by the same company Tom Henry sent yours to. Best of luck to you.

[tomtom72]

Don, Okay on this scanner thing, I would agree with Scott Fabre as it's the second best money I ever spent on my tool collection. A Tech1A is the schizzel but you need all the software so you can run all the functional tests in the FSM. The Master Tech would be the tits, but again you need OBDI / LT5 software suite to be effective.

I have an antique snap-on MT2500 with GM OBDI software package for power trains & ABS systems. However it will not do the functional tests in the FSM. But, it's better than relying on purely "generic" OBDI software as it gives me the complete LT5 library of DTC's as listed in the FSM....no translation needed.

I am sticking to the first set of DTC's you posted and my original first guess. Check the fuel pres at high engine load & high rpm. You proly had some oil in the MAP hose or sensor or both and the new MAP solved that issue. Make sure annually you clean the PCV valves. The lean O2 and the the DTC I said were related make sense if fuel starvation is an issue.

Also, when using someone's ECM, a 90 can use any year ECM with a 90 PROM, and you have to drive it enough to let it learn the car & your driving habits. That takes about 30 minutes at the least under varying conditions. They actually learn how you drive the car and adjust to it, but it takes time. Unless things have changed, the guy Gordon told me to call said the issue is that LT5 ECM's are unique. As of two years ago GM has not let anyone see the schematics and with out those ya can't fix much! It's not the parts, but the circuit diagrams that count. Maybe that has changed, but the guy told me that most places that say they can fix an LT5 ECM are using the L98/LT1/4 diagrams and extrapolating. After all they are all OBDI ECM's except for the LT4 ECM. I wonder if the MCN has those schematics on file? I still have my Minox! LOL


Tom

[c4zr1]

Tom,

Thanks for the feedback!
Where is the best place to order a Scanner that has the LT-5 software with it?

Thanks!
Don