Just put in SVO 42# injectors and was tuning. The car ran real good when the injector constant was set at 47#, that is the BLM's were somewhere around 128, not pinned out at 160 or 108.

Then, after 200 miles of driving and reprogramming, an intermittent miss developed.

Could it be PCM related, as in burning out an injector driver because I got to close to the 50# mark??

The car is back at the shop and they are in the process of replacing the wires now. I saw it on the scope and it did scope out real nice, no spikes what so ever, even when it was missing.

And BTW, we already tried a new opti and after its install, the problem got worse ... could it be a bad plug wire ?? A body does after all have to touch the wires when changing out the opti.

Thx for any input

LWM

 

There is a guy in LT1 Speed Density Board who had failed Quad Driver Modules. There are 3 such sets inside the ECM of 93, and his case caused his injectors to stay open at all times.......remember that 93's fire all at the same time (BATCH Fire) so the problem was made worse. He ran overly rich.......and picked I think half a second when it was fixed.

In my case I have Quad Driver 1 failure, and a interminttent failure of Quad Driver 3. I have not yet replaced my ECM, but my car runs super super rich, I do not ever run it anymore because of the risk of washing down the cylinders walls. It fouls plugs in minutes....

Problem is that I do not have reference to which driver actually controls injectors? That is what I am trying to find out. If you can find out, scan it to verify if it is your problem......

Good Luck

 

my pcm injector driver craped out on me
HAd to get another pcm, if anyone knows where i can get it fixed please let me know

 

Saint,

How you figure your injector quad driver crapped out?

 

cause my number 7 injector is not gettin signal from the pcm

 

Figured I should post the result of all the detective work.

It was a burnt spark plug wire, #5 to be precise, and that was even through a set of heat boots on the wire ...
Reason it didn't show up on the scope, was because it could fire against the header instead of the through the spark plug and give just about the same voltage spike.

I suppose what gets me is the fact that this is not the first LT1 car they have done ... that mechanic shouldn't have installed the wires in such a fashion ...

Oh well

thx for the input

LWM

 

I am having huge issues I think may be related to this....intermittent miss in #1, #2 and #4 cyls. I am assuming they are too rich because they all have good spark and the tailpipe emissions are nasty burn-your-eyes rich, but my fuel trims are positive as much as 20% at idle with pretty big splits from Bank 1 and 2 as well. Adjusting the injector constant does not seem to help this at all.

Wires are new, plugs are new, opti is new and LTCC coil pack conversion recently installed last weekend. Fuel pressure is good, new fuel filter too. It has to be fuel related.

So how do you guys diagnose a bad injector driver? WIll it flash a code?

 

Sounds like you have most of it covered ... are you absolutely sure the wires are going to the correct cylinders ... sorry to bring that up, but it has happened to the best of them.

Does it get worse under load? If so ... it may be ignition related.

Running rich and not responding to injector constant changes ... it could be the PCM, I think you just have to change it out and hope for the best. You could put in a stock PCM and put back the stock injectors and see it that cures it.

LWM

 

I'm confident it is not ignition related. Load does not affect it and the condition has existed through 2 optis, a new coil, module, and now the LTCC conversion.

Injector plugs and spark plug wires are definitely on the right cyls.

I'm to the point its either the pcm or its the wiring harness...but odd it would be those three cyls only that are affected or at least primarily affected.

Also tested resistance in the injectors. read 15.0 ohms exactly on all injectors incl. the good cyls.

 

You can tell if a quad driver is out with the use of a scan tool. I have an ACTRON OBD1 scanner, and it listed Quad drivers 1 and 3 are faulty.

I believe it was 12SECONDZ out in the speed density forum whom had the same problem. He gained good time when he fixed it......