Revs on idle

[lawser]

1995 2.6 E Coupe, On idle i've noticed that she sits at around the 1100 rpm mark & while motoring if i take the foot off the gas even slightly there is a marked hesitation instead of a smooth decelleration, on idle prior to the below comments she idled around 800 rpm.
I've recently added fuel additive to help with emissions on a near empty tank for the MOT, but in draining down the tank i more or less flatened the battery....Had to use a portable battery starter.
Having read some of the comments posted previously i guess my question is, " would either the additive or flat battery contribute to this symptom ? "

cheers,

[scotty33]

I've read a few posts where 2.6's have idle problems after a flat battery. It seems the Throttle Position sensor is affected, and needs to be aligned. This can be done using Vag com or this DIY method may work - can't hurt to try it?

Post by Vampire: https://www.vwaudiforum.co.uk/forum/s...ad.php?t=34879

The ECU fuses are the big ones at the front labelled 'moteur'

[lawser]

Yeah i've read the posts, thanks scotty33....looks like the battery is goosed, had it on charge all last night & this morning it looks like at least one cell is dead & it's not holding charge.....Oh well new battery needed.
Anybody any idea of battery type, this one has no markings that i can find other than it's heavy duty ?

[fourringsrus]

Hello lawser,just took a peep at mine ,'95 2.6 abc coupe, and it has the following written on it
12v 74AH 680A
Hope that helps

Stuart

[Norbee]

Hello Audi lovers

I hope it is OK to jump into others thread but why wasting server space.

My 2.0l 16 v L reg coupe has similar issue.
1100 steady idle.
Very very occasionally drops back into 800 and only for maybe a half an hour.

Any idea what to try?

Did the ECU reset thing but nothing really changed.
The throttle position sensor clicks properly and upon driving the rev falls back nicely no hesitation or playing up and down.
Just sits at 1100 idle

Thank you in advance!

Norbee

[lawser]

Sorry forgot to post back, new battery sorted out my issues, no need to reset anything....purring like a cat now !

[Norbee]

Well my battery is only 1 years old...
Do you think it could be alternator related?
If not enough in the battery then ECU revs up to have enough voltage?

Thanks for comments!

Norbee

[scotty33]

That sounds like the Idle Stabiliser Valve is sticking 'open'. Try soaking/flushing out the mechanical end with carb cleaner or petrol