My Mom's Duramax is acting funny.

Background Story
Moms D-Max had a plug-n-play chip from Western Diesel Performance on it. Great chip. But about 3 years ago the truck began acting funny. It would start, idle, and drive just fine but when you would begin to decelerate and stop the motor would begin to idle funny until you stopped, did it for a few more seconds, then go back to normal. I pulled the chip to see it it made a difference and it did. All was back to normal...and stock. But the truck ran great again and we didnt really miss the chip cause Mom's foot has all the power the family needs. It's all good.

Fast forward 3 years to the past few weeks...

Now the truck is doing it again. Its still 100% stock drivetrain wise.
As you decelerate it idles funny as if its missing 2 cylinders but the truck doesnt shake or sputter like a missing engine. It just SOUNDS that way. It still starts and drives just fine but when decelerating it does the odd-idle. And what else is odd that when it does IT, the tach doesnt seem to change with the sound. And as before, after being stopped for a few seconds it goes right back to normal.

The truck does not smoke at start up, or any other time for that matter. There is no check engine light on either. The mileage has dropped from the usual 17-19 to about 13.


Some people have told us its the injectors.

Im no mechanic but to me...that seems like a good guess but there is no smoke and it runs great, aside from its little deceleration tick.
I think its something electronic simply because the last time it did this, it was an electrical problem that was easily removed...but...there is no check engine light. I know check engine lights arent bulletproof but still...

Who know, maybe Im wrong on both counts.

I figured I'd ask here first before the parents decide to run out and drop, what...5K on new injectors?

Anyone have any ideas?


Thanks

 

Pay the diagnostics fee at a dealer first, go from there.

 

could be any number of things.definatley hook iit up for computer diagnostics...

 

you said its a 2002, so that makes it a LB7 dmax


Take it to the dealer have them check the balance rate on the injectors, an the FPRV ( fuel pressure regulator valve )

something you can do, is check the oil. does it smell like diesel is it super thin?

 

when i had my 02 d-max it was doing the same thing i took it in and they changed out all 8 injectors and it only lasted about 3 weeks and started doing the same thing again so i got rid of it anf got my 08 dodge

 

GM has seriously increased the warranty on those LB7 injectors. There's a good chance they are still covered if they are the problem. Can't remember exactly, but I think they're covered for close to 200k miles.

 

Thought I heard that GM extended the injector warranty to 200,000 miles on the 02's to maintain resale on that model year. Hope that helps. Twogun