TDi 130 - very lumpy below 2000 revs - ESP light on

[AndyMac]

Any ideas? Car shakes badly when trying to pull away at low revs and the ESP light is permanently on, no idea how the two are related. If I keep it above 2,500 revs it's OK, thought it could be the clutch (it's done 165k miles)but even in neutral revving the engine is horrible.

 

[Neil_S]

My usual first step would be to unplug the MAF and see how the car runs, some people say that if this is improved then it's usually a sign the MAF has gone, partly true, but in my recent experience it can also mean you have a problem around the turbo/EGR.

 

[AndyMac]

Thanks Neil I'll give that a go, the turbo's just been replaced so still under warranty (I hope).

 

[AndyMac]

Disconnecting the MAF makes no difference, I hope it's just some sensor and nothing major.

 

[Gti Jazz Blue]

Hi Andy - if memory serves me right you are not too far from me if you want the ECU scanned.

Regards,

Paul

 

[AndyMac]

Thanks for the offer Paul, but I doubt it's something I can fix even if I knew what it was. Got it booked into Abtech now so I'll let them deal with it. Thanks again. Cheers, Andy

 

[Gti Jazz Blue]

Well if you ever need in the future drop me a PM.

Paul

 

[timps]

Disconnecting the MAF makes no difference, I hope it's just some sensor and nothing major.

The ESP light being permanently on usually means a sensor has gone down or implausible value. If there is a fault with ESP this can effect how the engine runs as it ******* engine revs during wheel spin.

A common fault is the lateral acceleration sensor giving an implausible signal which does not always show as a fault just the wrong value while the car is stationary.

 

[Macduff]

Could be a faulty engine mount. IIRC, there are one or more active mounts that stiffen up when the revs increase and then soften at idle to absorb the vibrations.

 

[AndyMac]

Thanks Timps, is there anyway to switch ESP off other than the ESP button (which does nothing at the moment)?

Yes I thought it could be an engine mount but this wouldn't explain the ESP light.

 

[timps]

Unfortunately you can not switch the ESP totally off it is always on, just in varying degrees on your A4.

The ESP button will allow you to wheel spin (for use with snow chains) but never totally disengage the safety features(Although they will be toned down a bit).

If its a yaw sensor for example the ESP button has no effect on this sensor the same with the ABS sensors these are always on and will kill engine power apply brakes automatically in extreme circumstances such as a rear end skid whether the ESP button is pressed or not.

If its getting conflicting signals then its possible the car has gone into limp home mode and replacing the offending sensor is the only option.

Vagcom should bring up a fault but if not, you then have to look at the values and see which one is out whilst the car is stationary.

 

[AndyMac]

Thanks again.
Just tried taking the ESP fuse out, but it didn't like that!

 

[Gti Jazz Blue]

Other possible causes could be the brake light switch, these are problematic on other Audi and VW cars and will throw a fault light.

A scan is the answer as the light is on I would expect a code of some description.

All this guesswork is just that with out the scan.

When is the car booked in ?

Paul

 

[Neil_S]

I use Abtech too so you must be close by, if you need any vag-com assistance give me a shout.

 

[AndyMac]

Yes Southampton, Abtech couldn't fit me in until the 12th.
Brake light switch? The brake light has been throwing up random warnings even though both bulbs work.
But would this really cause lumpy idle and car shaking?

 

[timps]

Yes a faulty brake peddle switch can cause the ESP light and usually the glow plug light to light up.

This will put it in limp home mode and cause your engine to run horrible.

The reason for this is the steering wheel position & peddles etc. are all connected to the ESP system. A fault causes an implausible value the esp thinks the pedal is being pressed or not pressed conflicting with the other sensors on the car.


A scan with VAG com will shed light on this as it could be one of any number of sensors causing the problem.

 

[AndyMac]

****** sensors, they seem to be the one thing that regularly fails on Audi's, and to make the car undriveable because of some poxy microchip on a system that I don't think I've ever needed is quite frustrating.
Mechanics and computers do not mix!
My old B5 mechanical quattro has only ever had one issue in the last 3 years and that was a ****** sensor, but at least it was driveable.

 

[timps]

Your quite right I have had 3 fail on my car.

Not wanting to sound like a salesman but that’s why I love Vag com two I replaced for £50 and one fixed when I finally found the spring lodged in my dashboard when my clutch peddle switch exploded.

I dread to think of the price if a main dealer had been my first call.

 

[AndyMac]

Ended up taking the car to Peter Coopers (VW dealer) near the M27 and said the problem just occurred, I'd just limped off the motorway and could anyone have a quick look. They were brilliant! Within 30 minutes of arriving they'd found the fault and an hour later the car was all back to normal.
Turns out it was 2 different problems, the main one was a loose/broken wire on the plug to one of the injectors, which they replaced and secured all the others as well which were loose.
The other was the inevitable MAF replacement, which I think had been causing other issues that had got worse over time as she runs like a dream now.
The whole job was £164 incl VAT, they only charged an hours labour @ £65. Audi charged me half an hours labour just to change a dash bulb once during a service so I'm well chuffed. Couldn't wait for ABTech as it would have meant hiring a car for 2 days, so saved £60 there as well. Good to know some main dealers are a pleasure to deal with.

 

[doogleman]

alls well that ends well. glad it worked out for ya man.

 

[Gti Jazz Blue]

Well glad that is sorted and that you had good service from Peter Cooper Southampton.

My experiance with them when I had my Golf IV of them still leaves a bad taste in my mouth, I used to go out of my way and use the Dealer in Petersfield rather than darken their doors.

Paul

 

[AndyMac]

Maybe they're better with Audi's!
This is what scares me going to a dealer - it's just seems to be a lottery, when you want them to be a guarantee of quality service - why else would you pay their loaded labour rates.