Surging
Thread Starter
Pro
Joined: Feb 2013
Posts: 535
Likes: 92
From: Raleigh NC
Surging
2001 Corvette, Manual
I'm getting a slight engine surging at lower rpms, light throttle. Say cruising along at 1500rpms, you can feel a slight surging. It doesn't idle any higher than normal, but it does surge at idle too, maybe a 100rpm fluctuation. And it does seem to drop to a lower rpm briefly when you first press in the clutch when coming up to a stop sign.
Haven't changed anything recently, no dead batteries, etc. Quick visual inspection, no disconnected vacuum lines etc.
I thought about trying an idle relearn but from what I've read the car does that anyway once the motor warms up and you drive some miles.
I'm not entirely sure if this triggered it, or I just happened to notice it at the same time... but this started one day when I ran the AC. (which blows cold, no noises, etc). I rarely run the AC so this was one of the first times I've used it this year. But the surging happens even with the AC off.
No check engine lights. (actually an ABS light popped up recently but I doubt that's related)
Any thoughts?
I'm getting a slight engine surging at lower rpms, light throttle. Say cruising along at 1500rpms, you can feel a slight surging. It doesn't idle any higher than normal, but it does surge at idle too, maybe a 100rpm fluctuation. And it does seem to drop to a lower rpm briefly when you first press in the clutch when coming up to a stop sign.
Haven't changed anything recently, no dead batteries, etc. Quick visual inspection, no disconnected vacuum lines etc.
I thought about trying an idle relearn but from what I've read the car does that anyway once the motor warms up and you drive some miles.
I'm not entirely sure if this triggered it, or I just happened to notice it at the same time... but this started one day when I ran the AC. (which blows cold, no noises, etc). I rarely run the AC so this was one of the first times I've used it this year. But the surging happens even with the AC off.
No check engine lights. (actually an ABS light popped up recently but I doubt that's related)
Any thoughts?
Last edited by bigmackloud; Jul 12, 2016 at 12:39 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
100% On the mark and my very first thoughts.
Use MAF spray and spray clean the MAF and Carb Cleaner to clean the throttle body inside and the blade.
I would also double check for any small vacuum leaks between the MAF and TB.
BC
Thread Starter
Pro
Joined: Feb 2013
Posts: 535
Likes: 92
From: Raleigh NC
What's the best way to clean the backside of the TB and upper intake? Obviously with the engine not running I can take the intake tube off and wipe down the most of the TB and throttle blade. But for the back side of the TB and upper intake, can I spray cleaner in through the clean air port?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
PUSH it open with your finger and clean the back of it and the opening around and behind it. EASY PEASY.
NOTE. It will NOT SNAP back to the fully shut position when you let it go!!!. It will FLOP back to a semi shut position! NORMAL!
NOTE2 Grab a flashlight and look inside the intake manifold and check out all the oil on the manifold floor! LOL! 
BC
NOTE. It will NOT SNAP back to the fully shut position when you let it go!!!. It will FLOP back to a semi shut position! NORMAL!
NOTE2 Grab a flashlight and look inside the intake manifold and check out all the oil on the manifold floor! LOL!
BC
