noisy, lumpy when cold or after long run hot - 1.9tdi

[Gordyb]

Hi

My A3 has developed a new problem (couple actually but different thread for the other).

It's a 1.9tdi 2008 model. It starts perfectly whether hot or cold but after a cold start it runs particularly rough and is noisy and down on power. it cures itself after a 10 minute school run, but has now been like this every morning after being left overnight for the past week. I've also noticed an increase in roughness and noise after one long run when it was obviously hot but on that occasion no loss in power, might be related. The noise roughness when hot wasn't as much as after a morning start.

I don't know enough about diesel engines to start to diagnose. I assume the roughness and "tappety" noise coupled with less power means not running on all cylinders? Could it be fuelling or would that not cure itself as it warms up? Something electrical?

No lights on the dash, no smoke from exhaust, not using any oil or water.

Car has done 150k, has had a new turbo, oil feed pipe, dpf sensor and service 2 months/8k miles ago.

Thanks for any help you can give!

Gordon

 

[Gordyb]

Bump to top

Also, found a few threads looking at possibly fuel delivery, saying it is a seal on the fuel pump?? Also possibly a battery related issue. Can anyone clarify please?

Thanks

 

[Gordyb]

Do these cars have hydraulic tappets? I've had issues with other petrol cars where they didn't "pump up" properly until the cars been running a few minutes. Didn't loose power though it was just a noise on those.

Thanks

 

[Gordyb]

Quick update, after reading another thread where they tried turning the ignition on and off several times before starting the car (apparently to prime the fuel pump or lines) I got it to start this morning without the noise lumpiness and lack of power. This was 5 times on off before starting the car.

Can someone explain why this worked and what fault I should be looking at fixing?? Confused....

 

[Gordyb]

Bump, can anyone tell me what to check?