Howdy all,

we're facing a problem with a 1997 K1500.

She is very difficult to start, does after several cranking, and when she starts, the idles is very rough, throwing a lot of black smoke.
If you let her idle, she will run very low, about 500 rpms or less, rough, and die.
You can rev it up a bit, always rough and smoking a lot, and as soon as you release accelerator she dies.

More than a month ago, she has been experiencing stalls previously, because of a dead PMD.
Being a bit short of money, he tried to keep running with a used PMD, with more or less luck.

While she was experiencing this PMD problem, we hooked a laptop with AE scanner, and here are the codes we found :
several ones about shift,
others about IP. Note the PO266 showing : cylinder 2 injector circuit contribution / balance defaut
Despite these codes, she was running fine, except stalls
http://www.dieseltowingresource.com/attachment.php?attachmentid=7820&thumb=1&d=1248562537 (http://www.dieseltowingresource.com/attachment.php?attachmentid=7820&d=1248562537)

Yesterday, we received the new D-Tech PMD and install it, remote mounted on a heat sync (the one from SSDiesel kit), outside engine bay.
The guy crank, and shefired right away, idling like a charm.
He let her iddle for a while. After 5 minutes, she started herself idling down to 500 rpms and started stumbling hard, black smoke, and died.
He killed batteries to try starting her again, as she was stalling after few seconds.
Then, we tried to swap to the old PMD which was causing stall but was allowing to run fine : same result.
- We pull out the resistor from PMD (#9)
- We connected the PMD on the stock harness to see if te extension was fine
- we disconnect both batteries, then disconnect the PCM for a while
still no luck.

The AE scanner shows these codes http://www.dieseltowingresource.com/images/smilies/eek.gif :
http://www.dieseltowingresource.com/attachment.php?attachmentid=7821&thumb=1&d=1248562537 (http://www.dieseltowingresource.com/attachment.php?attachmentid=7821&d=1248562537)

I forgot to mention that the IP is 3 months old and was said to be brand new..., remember at previous scan, that P0266 was showing...


What the hell mean these codes ?

After we disconnect the PCM for a while, cyl 1 and 5 do not show up in the code list, and she was running just a little smoother...

any idea ? we're a bit lost, and the young guy is really really sad and disappointed...

bump?

I do believe this problem has an electronic origin. The problem is that I've no idea where to look for.
IP harness ?, PCM itself ? Optic sensor ?

injector balance codes with specific cylinders listed.

I guess it's like a misfire perhaps? When my OS filter harness went bad the truck would randomly misfire(you can really tell with the straight exhaust and stacks and it coughs pretty loud). I would get a P0251 with the bad OS filter harness.

Sorry i can't offer anything more than that. I've never seen this before. Hopefully someone else can be of more help. :o:

Thanks for your 2 cents Dave ;)
Do you think disconnectiong the optic sensor will help in diagnosing ?

Fuel pollution or dirty optic sensor ?

can you get a sample of the fuel? check and see if it's cloudy.

If the fuel is cloudy then the OS will have a harder time seeing through it.

you may be able to disconnect the OS and see if that helps with diagnosis.

Finally, it is cured. The CPS was the culprit.
After we changed this Censored sensor, she fired almost fine, and did really good after I performed a time set...

No more codes now, and nice sleep for us tonight :D

Congrats! Diagnosis is so often the hardest part of the cure!

Chaser

Finally, it is cured. The CPS was the culprit.
After we changed this Censored sensor, she fired almost fine, and did really good after I performed a time set...

No more codes now, and nice sleep for us tonight :D

Finally, it is cured. The CPS was the culprit.
After we changed this Censored sensor, she fired almost fine, and did really good after I performed a time set...

No more codes now, and nice sleep for us tonight :D



I'm having the exact problem on my 95 Tahoe with 6.5 TD. Matuva what is a cps?

I'm having the exact problem on my 95 Tahoe with 6.5 TD. Matuva what is a cps?


CPS is the "crank position sensor".