A4 1.8TQS cutting out

[Nogwuy]

had this problem for a few weeks and it's got so bad I can't drive the car. Started with just a judder where by the revs drop then come back again, now it also just cuts the engine completely and I have to leave it for a few minutes before it will start. Can Happen at any time, ie under load or not, straight road or on a corner, doesn't seem to matter. Have changed the plugs and run Vag com a few times but no errors show up. Was thinking either throttle body or maybe maf or coilpacks? I have also tried the throttle body reset after disconnecting the battery but it's just the same and is now getting more frequent. There is sometimes a low pitch electrical drone noise that cones from the throttle body itself which I noticed when the ignition is on but the engine isn't started, doesn't make this noise all the time though, is it normal? Or indicative of a problem? Any ideas or advice would be great. Cheers

 

[Nogwuy]

been to Audi today to pick their brains. They recon it could be power supply or fuel pump related, or maybe a dodgy relay or earth somewhere. Any thoughts on that?

 

[aragorn]

the TB noise is the self adaption cycle, that's nothing to worry about.

It could be an electrical issue, but those are just random guesses really.

When you say the revs drop, do you mean the needle, or the engine itself.

The reason i ask, is that if your driving along at say 3000rpm, and some electrical fault interrupts the ecu or sparks, the rev counter would likely drop to 0, then return, whereas obviously the engine itself hasnt stopped.

If it was fuel related, ie the pump or its relay, i would expect the rev counter to stay where it was, as the engine/ecu/sparks are all still fine, theres just no fuel to create any power.

 

[steveboyo]

Hi
Have you checked the fuel filter? I had mine changed about 4 months ago and noticed a immediate change in pick up/idle. Audi say to change every 20k but very rarely is it changed on a service.
Steve

 

[Nogwuy]

thanks for the replies, when the revs drop the needle goes down as well as the engine actually slowing, causing the car to judder as you drive. Unless it cuts out completely of course then it just stops completely, and has to be left for a few minutes before it will fire up again, it turns over just won't go? Wierd and annoying! Got tomorow off to try and sort it again so any further suggestions appreciated.

 

[aragorn]

Sounds a bit more like fuel then at a guess. If it was sparks or ECU i'd expect the rev counter to drop to 0 or jump around a little rather than just following the engine rpm down, and the ECU can notice crazyness going on with sparks, but it cant really tell if the fuel pump dies.

When it breaks, you need to see if your getting a spark, and if your getting fuel. Fuel and no spark will give you wet plugs.