summertime high idle with acceleration held back

[KMyrick]

I am experiencing issues with what seems to be the exhaust brake engaging while in park. The engine will go to a high idle and the engine gets a muffled sound to it. When this happens, you can start from a dead stop and accelerate but the truck will not go as it should. It feels like the exhaust brake is kicking in are holding the truck back while trying to go. Any ideas?

 

[Mingoglia]

Since your truck is a '15, sounds like a trip to the friendly dealer may be in your future. My '15 certainly doesn't do that. I'm in AZ so I see similar temperatures as you.

 

[MichaelOverfield]

My 2009 does part of what you describe, and believe the high idle, muffled sound and sound or exhaust brake at idle is normal for my generation truck, part of avoiding the soot build-up issues.. not so sure on the '15 (but you posted in the 3G Engine and Trans forum..). If I had to guess from what I've studied... sounds like your variable vane turbo is sticking in position, so the response time to take off the exhaust brake with the engine at idle is slower than it should be, thus your from stop starting hesitation. In the 3G trucks I've read soot could cause this to stick and a way to avoid it was to ensure the vane was cycled often.. that may still be true in the 4G trucks also.. Does the condition clear eventually when you drive? If so that seems plausible as to what you are seeing.. do you do considerable idle time? If so this is where that condition seemed to be worst on 3G, but I'm understanding the DEF limited the EGR considerably, and thus helped eliminate much of the soot build up.. but seems it could still be a possibility.

 

[KMyrick]

Thanks for the response guys. I will pass the question to the right forum, darn phones and small font. I have to agree that there must be a sticking issue. The condition does clear once you can get going. I will keep an eye on it.