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Hi all

Ive recently picked up a 1998 B5 S4 with 83K on the clock. Full main dealer history, cam belts at 53K and 83K (asked for it to be done again when purchased) ....anyways all that is fine, but now ive got a problem with the idle.

Basically start up from cold and it fluctuates from 1000-1600rpm. When warm it sits at 1100rpm, then climbs to 1600rpm after a couple of secs.

When driving I notice when I back off the throttle its a little jerky, and the part throttle response at 1300-2000rpm is very jerky to.

Any ideas? could it be the diverter valves are duff?

thanks in advance

Welcome mate,

There are loads of members on here who will be able to come up with some educated guesses. Best thing though is to get it diagnosed on VAG COM. Go to the local dealer or specialist. You may be lucky and someone in your area may have VAG COM and look at it for you.

Ok - ta...dealer is only 5 mins away, so I may pop down there at the weekend

umm you might find the jerky off throttle to be a 'feature', the drive train moving due to the change in torque but I could be wrong. Jerky throttle type shenanigans can also be caused by dirty/faulty MAF's & the other favourite - DV's. Have a search around on the board, there is a lot of good info on there on things to check & how etc. It's also worth investing a couple of quid in a vag-com cable

Oh & welcome to the fold

I was wondering about the 'jerkyness' as Im not used to turbo cars (my other cars are NA and Supercharged) ...I was thinking at 1.5-2K revs it may just be coming on/off boost when Im on a light throtle opening. The high idle thing is a bit weird. Ive just ordered some Forge DVs, so will fit them and see what happens

Dump Valves would be where I'd start looking. Be suprised if it does it once the Forge units are fitted.

Jerkiness is not normal. As dazzer states, without more information it is all speculation. However known problems with this car include the G62 temperature sensor and the DVs.

OK - ta....didnt think that Audi would make something that had such poor part throttle mapping ....Think a trip to the local dealer is in order for a health check. At least if they tell me whats wrong, I can replace it myself if its something simple :up

fade2grey wrote:umm you might find the jerky off throttle to be a 'feature', the drive train moving due to the change in torque but I could be wrong...

I have the same problem (very slight 'jerkiness', for want of a better term) in my 01' avant s4, and it certainly seems to be more of a drivetrain problem than throttle problem. My mechanic, who does work on quite a few S4s, also says this is a 'feature', on a lot of S4s...anyone have any idea what the root of the problem is, assuming it IS torque/drivetrain based ? (The aforementioned mechanic only speaks french, and I sometimes have a slight issue discussing technical points). And is there any way to fix it without spending big bikkies ? It's not a huge problem once you get used to feathering the throttle to counter the jerks at certain revs/on certain inclines, just annoying. My car has 48 k miles.

btw, welcome, bogie ! I'm a newbie myself...

right - problem solved ! went to dealer...wouldnt even look at it for a week so went home. Anyway Forge DFVs turned up that I ordered so fitted them - no more jerkyness on part throttle at all, and idle back to 800-900rpm when warm.....sorted

...right now for a remap with MRC

http://www.autospeedperformance.com/ can sell you a TRANSMISSION STABILIZER BAR for $279 +delivery this will fix the kangaroo first gear problem.

kies4 wrote:http://www.autospeedperformance.com/ can sell you a TRANSMISSION STABILIZER BAR for $279 +delivery this will fix the kangaroo first gear problem.

Thanks ! That looks like a handy thing. (Which I didn't know about.)
Might hunt around to see if a more 'local' equivalent exists, otherwise will seriously consider getting one of these.

Anyone else had experience with them ?

Btw, its not just in 1st that I have the judders, but sometimes at highway cruising speeds, if I let off the throttle on a downward incline for eg., or gas it suddenly...

If you get the ASP bar make sure that you chase out the threads on the tranny before inserting the 30mm
hex cap screws. They are A2 stainless and aren't as rigid as high tensile bolts. As a result of which I have two
sheared off bolts in my transmission and a fancy aluminium lower tie bar.

A few of the lads on here have recently fitted the AWE DTS and I think they reported excellent results. It is certainly on my list. There is an interesting report on AudiWorld by someone but I can't find it - will trawl later. He compared the snub mount against the DTS and also with them both fitted. Think he also recorded on video camera underneath the car what effect it has on the drive train.

I have learnt to smooth out the jerky movement experienced at power on/power off. I might check out my DVs this weekend however.

Certainly the AWE DTS tightens the transmission but does not the "slack" altogether.

Interesting that new DVs fixed an idle speed problem. I would not have expected that.