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emilebos
08-01-2020, 05:00 PM
Hi all,

What idle speed should a stock LS1 have in both Drive with the brakes applied, and in Park?

My VU SS is currently running at 650 rpm in Park which feels smooth, but in Drive with the brakes on it’s running at around 550 rpm which seems too low as it’s causing excessive shudder.

Pulled the IAC a few days ago and cleaned a lot of built up crud. Seems to run a bit smoother now, but the shuddering in Drive is still not really fixed.
whitels1ss
08-01-2020, 09:36 PM
Those numbers around the factory specs as listed on the emissions sticker IIRC. :yup:
emilebos
08-01-2020, 10:11 PM
Hey, good point, the emissions sticker! Never would have thought to look there.

Sticker says: IDLE R.P.M. 775 +/- 50 (AUTO) & 925 +/- 50 (MANUAL)

So I’m under the auto factory specs by around 100 rpm. How can this be adjusted up, or can it be adjusted at all?
whitels1ss
08-01-2020, 10:27 PM
Hey, good point, the emissions sticker! Never would have thought to look there.

Sticker says: IDLE R.P.M. 775 +/- 50 (AUTO) & 925 +/- 50 (MANUAL)

So I’m under the auto factory specs by around 100 rpm. How can this be adjusted up, or can it be adjusted at all?

I am down on the great ocean road on holls at the moment so as I said I was just going from memory.


It is normally only adjusted in the tune.
emilebos
12-01-2020, 06:52 AM
It is normally only adjusted in the tune.

Did a TPS reset yesterday, also seems to have made a slight improvement with the in drive idle now at 580

How about the set screw on the throttle body, can it be used to adjust the idle any?
whitels1ss
12-01-2020, 07:00 AM
How about the set screw on the throttle body, can it be used to adjust the idle any?

No, don't touch it mate. That is not something for normal user adjustment.

You might have something else causing your problem like leads, spark plug, coil or vacuum leak?

I would keep investigating for a physical fault. :cheers: