backfire sound

[cbrahs]

ok, I have talked about this before (last winter on another site) and the truck is starting to do it again :bang . In the mornings when the wait to start light comes on I start her up. wait for oil and everything to stabilize then kick on manual high idle to 1100rpm. when the grid heater cycles OFF the motor sounds like it backfires. It shakes the truck and usually only does it one time (NO CHECK ENGINE LIGHT AND NO CODES). I know what a backfire is, I am just using that as an example of what it sounds like. I have been shooting videos each morning to capture it on my phone so I can post it and show the dealer. It only happens when it has cold soaked usually overnight. Once it happens it usually does not do it again hence the PAI to get it on video. I will see if I can catch it on video and post it here to see what people think. Any help or ideas will be much helpful.

BTW- it was doing it long before I installed the bodylift (bodylift has a 3" spacer for the intake horn

 

[Cummins Driver]

Im pretty sure what you have is a typical diesel. They just have to warm up a minute in the winter before they smooth out. Try letting it idle for a minute before you kick on the high idle.

Eric

 

[SuperSonic]

Try it again with the AC off. Our 05 was doing this and I eventually figured out that it was the ac pump kicking on just after startup. Makes a pretty good thump.

 

[cbrahs]

A/C off already. do defrost either. I am sure I will be able to get a vid of it here in the next day or so. will post it so people can see what i is talking about. Have had MANY diesels and never seen anthing like this.