[JoeFrontier68]

Taking it in tomorrow morning, but thought I would see what you all think.
I picked up a 16 SL with 11k on it 2 weeks ago. I noticed it idled at 550 rpms at a stop and had a bad vibration. So took it back to the dealer last Saturday to look at it. Was told the tech could not adjust the rpms.
OK, maybe I'll get a second opinion.

Saturday afternoon and today I noticed that the idle was now 1k at a stop and even worse, it would surge to 1200 rpms when coming to a complete stop. It takes a heavy foot to stop and will drop to 750 rpms after being stopped for 30 seconds.

I'm think the tech did something and thought it didn't work but it really did change the rpms. Can the rpms be adjusted?

Opinions?

 

[Skibane]

Yes, the idle speed can be adjusted somewhat - But it sounds like you've got something else going on there.

Vacuum leak in the power brake booster, maybe?

 

[fastfed]

dirty mass air sensor is my guess

 

[smj999smj]

Base idle and ignition timing can be adjusted slightly using a capable scan tool or tuner. I wonder if he did something to erase the learned idle air volume memory, which would mean an idle air volume relearn procedure would need to be performed.

 

[ZackAttack]

I'm having the same issue after the dealer cleaned the throttle body and did an idle relearn. Planning on cleaning the maf sensor to see if that helps. I took it in because the truck was idling low & vibrating like crazy. That issue is gone but now this is happening lol. I'll let you know if cleaning the maf sensor works.