Revs hit the floor!

[Paulgo]

Got an intermittent problem whereby the car sometimes dies when I slow right down, i.e changing down into second - usual culprits are junctions and speed bumps etc. As I either back off the throttle or brake instead of the revs being caught and kept around tick-over level sometimes they just keep on dropping to a couple of hundred revs or lower and the car just dies. Starts up immediately each time and otherwise I’ve no running problems.

So whatever would keep the revs from falling below 800 revs or so when there’s no throttle on these random occasions isn’t! It will also die sometimes if I break hard. The rev’s just hit the deck.

And it is random! Sometimes I can go a couple of days and it won’t do it at all. Other days it’ll happen just once then be fine and then do it again, always managing to take me by surprise. Had a few slightly hairy occurrences taking right hand turns across traffic when I’ve lost steering and power in the face of oncoming traffic! Not the best!

Jas will kindly vag-com the car for me when I manage to sort it out but in the meantime are there any obvious causes that anyone can think of?

Cheers

Paul

[Acidburn]

idle valve i'd say, sounds same as another car i've been driving recently, quick clean out should sort it. Sounds like it ain't kicking the revs back up in time.

correction, re-read that. Have you got your foot on the clutch at the time? if so then the above could still apply.

[Paulgo]

THe ISV was the first thing I thought of but cleaning it hasnt made any difference - unless it's something else in there. Not really thought much about the clutch but I think most of the time it happens I would have the clutch in. cheers

[Acidburn]

is the rest of the car all right, no exhaust blows etc??

Does it do it at all at stand still?

[Paulgo]

No exhaust blows and all else seems fine. Only ever does it when I slow down and back off the throttle - such as getting ready to change down to second at junctions etc Its completely random when it decides to do it too.

[spink]

ISV could well be totalled,no amount of cleaning will sort those out.Had a couple like that recently.They are found on loads of other audi engines aswell so not hard to find.

[Acidburn]

Hmmm sounds more like a loose wire or something. Could try take it down the local car park and drive up and down, coming on and off the throttle and see if anything happens.

have you done any work to the car rececntly? check all the plugs / wires connected to the engine.

[AUDIS2avant]

Mine has just done ecatly that, and it mas a maf issue, as i could se it stoped after i changed it, and havent done it since.
So my diagnose is maf-sensor

[Paulgo]

cheers guys. I will keep an eye out for a replacement ISV and I have a spare MAF so no harm swapping them over to see if it makes a difference

[europeanme]

does this problem occur when the engine is warming up??....as I to have the same problem....

[Paulgo]

not noticed it when the car is cold - its awlays when the car is fully warmed up

[Acidburn]

Sounds like the isv is working and keeping the rev's up that little bit so that it will work, as others have mentioned looking more like the maf.

[Ross]

It's odd... I had the same issue when moving to the GT3071 as have many others but never heard of it on stock! Solution was moving MAF to pressure side due to screwed up readings, so i also would suggest trying a good working MAF to see if that's the issue.

[Paulgo]

The MAF seems to be emerging as a likely contender and very fortunately I have a spare working one so will try that Hopefully get vag-com on tomorrow also, thanks to Jas cheers guys

[Paulgo]

Well the code ares clear and both the ISV and TPS checked out fine with VAG-com. Swapped MAF’s too but its still doing it cutting out at least two or three times on my daily drive to and from work - and only when I back off the throttle and slow the car down (i.e changing down into second) .

All thoughts welcome!!

cheers

Paul