LT1GMC

My manual trans car revs up between 1-2 and 2-3 shifts sometimes, like when engine is cold, and also if you have been sitting a while with it running, like at a long stop lite or car wash (no touch). Its just like you forgot to take your foot off the gas. Makes you look like a novice stick driver. Is this an emissions thing, or is something not right with mine? Anyone else have this? Thanks!

relicstone

how far does it rev up. my old car used to spike about 500r between gears. My SS does not.

LT1GMC

It doesn't actually "rev up", it acts like you never let off the gas when you shift, so its is at like 3000-3500 rpm with no pressing of the gas pedal when you press the clutch in. (kinda like the gas pedal is stuck).

ChevyMgr

Check your floor mat to make sure it isn't bunched up under the pedal as in this thread.

https://www.chevyhhr.net/forums/show...t=winter+floor

If not you might want to get that checked out.

LT1GMC

Nope, no obstruction with the mats. Tested it at noon, after sitting in a turn lane thru 2 lites, it did it, then I pushed the clutch in, reved to 4500, and it stayed there a few seconds after I released the gas. I did it twice, then all ok. Its like the engine control is doing it, of course it can since we have throttle by wire, but nobody else has this? I at first thought it was some kind of emissions deal, to let the throttle off easy when hot, but am more thinking its a problem.

jonboyb

Mine does it on the 1-2 shift if I don't have my foot COMPLETELY off the gas pedal before hitting the clutch. The revs just hang there.....and yes, it make me look like a novice manual driver. Never done it on any other shifts, just 1-2.

DreamHHR

I think it's normal... it's for reduction of emissions.

Looky here:

https://www.chevyhhr.net/forums/problems-service-repairs-42/gas-pedal%5Cregime-needs-adjustment-11076/

Yves

jzr28

Could it be this???? "Getrag five-speed manual transmission with "Zero-Lift" shifting". Sure sounds like it. Just my $.02

ivtech

Ditto

Nebulous1

“Zero-lift Shift” is a system where you can shift gears without lifting the accelerator. In most manuals, you lift the accelerator to avoid runaway RPMs while the clutch is down and you are switching gears. With ZLF, you keep your foot planted, while the computer limits the revs to 4,500 RPM, keeping the turbocharger spooled up. GM says it saves about 0.07 seconds per shift. So, if you can and want to unlearn years of reflex, and you won't accidentally do it in another vehicle...

1.Floor it to redline in current gear. Don't let up during the shift process.
2.Depress the clutch.
3.Switch Gears. Engine revs to 4,500 RPM.
4.Release the clutch.

I heard there's typically a backfire during ZLS because the RPMs limited, but the fuel is not, resulting in unburned fuel igniting afterwards. I haven't tried it yet. Maybe after the engine is more worn in.

That said, if my vehicle was revving up for no reason I would definitely bring it into the dealer, because that just doesn't sound right. I've had vehicles which had a constant higher rev at idle until they reached normal operating temperature, but this sounds like a random fluctuation. If the dealer says it's normal, get them to demonstrate it for you on another vehicle. If they can't, make 'em fix it.