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+--- Thread: Engine Braking and ICV (/showthread.php?tid=8586)
Engine Braking and ICV - lewisdmz - 04-12-2012
Does anyone know how the various sensors interact with each other to bring the revs back down to idle once the throttle is shut at high revs?
I understand fuel is cut on the overrun and if the throttle is closed presumably the ICV must be open? Or does it only open when the revs drop to idle speeds?
RE: Engine Braking and ICV - Ed Doe - 04-12-2012
What are your symptoms?
I still feel I have overly heavy engine-braking, despite having replaced the MAP, TPS & lambda....
RE: Engine Braking and ICV - Matt - 04-12-2012
Maybe it's your actuall brakes....
RE: Engine Braking and ICV - Ed Doe - 04-12-2012
Thanks Matt, but no. It's definitely engine-related.
Anyway, Lewis, from what a few have said on here previously (and in my engine issue thread on the '6 forum!) the ICV only opens at idle, when coming off the throttle in gear it doesn't do anything.
RE: Engine Braking and ICV - Rippthrough - 04-12-2012
Starts to open when you drop through approx 1250rpms and adjusts fuelling/airflow from there. There's a slight delay on it to give it some hysterisis.
RE: Engine Braking and ICV - cully - 04-12-2012
ICV only opens moves when the throttle butterfly is shut/near shut
as the ICV regulates air bypasing the butterfly
RE: Engine Braking and ICV - Niall - 04-12-2012
(04-12-2012, 01:33 PM)Ed Doe Wrote: What are your symptoms?
I still feel I have overly heavy engine-braking, despite having replaced the MAP, TPS & lambda....
Do you ever give up?
RE: Engine Braking and ICV - lewisdmz - 04-12-2012
(04-12-2012, 01:33 PM)Ed Doe Wrote: What are your symptoms?
I still feel I have overly heavy engine-braking, despite having replaced the MAP, TPS & lambda....
Nothing really, always thought the engine braking felt a bit heavy in the GTi at low revs and it just got me thinking that was all. I know my ICV is a bit dicky as well so thought the two could be related. Mine certainly isn't excessive enough to get me worried, are you sure your new engine isn't just healthier so there's more compression to fight against?
My theory with the ICV would be that if it is meant to open slightly to let the revs drop slowly, if it was shut/slow to open this could cause a harsher drop in revs.
(04-12-2012, 04:28 PM)Rippthrough Wrote: Starts to open when you drop through approx 1250rpms and adjusts fuelling/airflow from there. There's a slight delay on it to give it some hysterisis.
Really? So there is no air at all entering the engine if you lift off at 5500rpm and it drops to ~1250?
RE: Engine Braking and ICV - miles - 04-12-2012
The ICV never fully shut's, It generally stays at it's last position and goes from there, The power steering sensor can cause stalling as well
RE: Engine Braking and ICV - Rippthrough - 04-12-2012
(04-12-2012, 07:19 PM)lewisdmz Wrote: Really? So there is no air at all entering the engine if you lift off at 5500rpm and it drops to ~1250?
As miles says, the throttle/ICV never completely shut, there's always some air passing through.
RE: Engine Braking and ICV - lewisdmz - 05-12-2012
Thanks guyss