Chevy/GMC 6.2L and 6.5L Discussion of Chevy and GMC Trucks with 6.2L and 6.5L Diesel Engines

6.5L - lots of black smoke during acceleration

Old 09-23-2018, 09:10 PM
Tahoe2DR's Avatar
Thread Starter
Join Date: Mar 2018
Location: Washington, DC
Posts: 5
Likes: 0
Received 0 Likes on 0 Posts
Default 6.5L - lots of black smoke during acceleration

I have a 1999 6.5L with about 300K miles that puts out a lot of black smoke when I accelerate. I think it's something with the wastegate or EGR but looking for help to diagnose.

I got code P0236 (Turbocharger Boost Sensor A Circuit Range/Performance.) I replaced the Wastegate solenoid and cleaned the inside of EGR valve as best I could and the codes went away, but not the black smoke. I get the correct vacuum from the pump (the needle is steady at 25 in-Hg) and about 14/15 in the wastegate line, the needle fluctuates. Should it fluctuate? With the solenoid removed, should I be able to blow through it?

The wastegate actuator arm moves when the engine is off and is pulled up when the engine is idling. Is there more I can check? Is it possible to take the wastegate apart?

Previous Issues/History:
-When I bought the truck, it showed code P1653, would idle fine but rev up to redline if I tapped the gas pedal. I replaced the PMD and the run-away RPMs went away after 10 or 20 restarts.
-The injector pump was replaced by a previous owner. (I have the old pump if anyone wants it) Could the issue be injector timing?
-Could black smoke be leaking injectors?

Thanks for reading.
Old 02-10-2019, 08:47 AM
racer55's Avatar
Diesel Bomber
Join Date: Oct 2012
Location: Scugog Island ONT.
Posts: 1,848
Likes: 0
Received 103 Likes on 103 Posts

when the engine is idling safely attempt to pull the wastegate open against the force of the diaphragm,if you can easily overcome the actuator it is most likely faulty-it should take a good amount of effort against a finger or 2.

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.