Gentlemen, I have a easy question for ya'll. Can a bad computer tune cause the front 4 cylinders to be lean and the rear 4 to be black sooty rich?
I always thought the pcm controled the left bank and right bank as 2 individual groups. If I can eliminate the pcm then it must be my new Bosch 36 lb. injectors. I can't imagine the odds of installing 4 new bad ones on the back 4 cylinders and 4 good ones on the front 4 cylinders, but as I have found out anything is possible.

Thanks for the help,
Dean

 

To test the injector theory, move two of the rear injectors to the front and watch the plugs for a while (move 1 on each side).

Yeah, I could see a tune causing this problem because there is the cylinder balance table, and you can adjust each cylinder individually that way. How that table would get out of whack, I don't know, but it's possible.

 

The computer controls each injector individually. There are two tables for this, idle and off idle. i doubt anbody jacked with them, at least not intensionally. You would need to monitor EGT's at each cylinder to trim it out correctly.

 

Thanks for the help fellas. I'm inclined to believe the tune is the culprit. The odds of getting 4 out of 8 bad injectors and installing all 4 bad in the back is unlikely. The engine in question is a 11.3 CR 383, CC 233/239, Combo stage 2 heads etc. Swapping the injectors is a good idea.

Thanks again,
Dean

 

Gentlemen, the tune was the culprit. It seems the person who edited my pcm adjusted correctly for the front 4 cylinders and incorrectly for the rear 4.
Bryan@pcmforless emailed a new tune and it's running much better. Best $50 I ever spent. Thanks Bryan.

Dean