What governs my diesel fuel mixure?

[Cupra Ross]

http://www.dieselbob.co.uk/injectors.shtml

This is one of the better known ones but you'd either have to have a garage remove your injectors or remove them yourself. Its not going to be camshaft related if it was replaced 20k miles ago.

The simpler 90 and 110bhp non-PD TDis don't really suffer from these problems. I think you're suffering from the joys of a higher mileage PD.

 

[Cupra Ross]

This lot would appear to be a bit closer to you: http://www.colfuel.co.uk/

 

[martincloud9]

It's kinda sad. I bought a diesel because a friend of mine has one with 300000 on it and never had to do anything to it except a regular service (engine-wise).

It also seems a twist of fate. I also have an MGTF which is running lean in closed loop which I have only found 1 person who has had this problem, and they never got it sorted.
One car running rich, the other running lean.... The only thing in common apart from being a pain in the neck, is that it almost appears to be unsolvable.

Thanks for the info. Has anyone else that you know of had a rich running diesel because of the injectors?
It seems weird, this wasn't over loads of miles. It was over about 3000 and after using this injector cleaner stuff a couple of times....

 

[Cupra Ross]

The top end of the PD engine is not in the same league as other diesels in terms of being trouble free at high mileage. They develop good power but its not a car I would buy at higher mileage. I think VW developed them very much with the 3 year owner in mind.

A diesel can't really run rich in the same way as a petrol because intake air is not restricted on a diesel engine. It always takes as much air as it can get, whether the accelerator is fully released or pushed to the floor. Diesel injectors wear at a far faster rate than their petrol equivalents due to the extreme pressure they are working at. If you think of the injector nozzle as an ice cream cone with a small hole on the end, its inevitable that this hole will get larger as the miles pile on and the parts wear down. This does not mean that it will inject more fuel, all that happens is that the same amount of fuel is injected at lower pressure and in a sub-optimal pattern.

For what its worth, I'm still not convinced that this is injector related. I'd be looking at EGR and VNT vacuum leaks and electrical gremlins first.

 

[martincloud9]

You're right, this car seems like it is committing suicide!

I was thinking along the lines of a turbo pipe leak, but i am not sure how to test it. I thought about getting a tyre valve and attaching it to the MAP hole and banking off the pipe nearest the air filter after the MAF. Then using a compressor (fully charged and unplugged for silence) to charge the system. What pressure does the system use?
Also, how can I sure that the vacuum lines are up to scratch?
All these VAG-COM numbers and blocks, I'm not totally sure what results I am looking for and what to do with them. Info seems to be sparse in these areas.

 

[Cupra Ross]

You're right, this car seems like it is committing suicide!

I was thinking along the lines of a turbo pipe leak, but i am not sure how to test it.

I think thats probably a bit closer to the mark.

I thought about getting a tyre valve and attaching it to the MAP hole and banking off the pipe nearest the air filter after the MAF. Then using a compressor (fully charged and unplugged for silence) to charge the system. What pressure does the system use?

I'm not sure what stock boost is on the PDs, I'm sure another forum member will be able to advise you. Its definitely a lot higher than the petrol turbos.

Also, how can I sure that the vacuum lines are up to scratch?

They go brittle and porous with age and exposure to engine heat. Replace them with silicone vacuum hose. Its about £4 or less per metre. www.elkparts.com are very cheap for this, they are Saab/Volvo specialists but their vacuum hose is universal and good quality.

All these VAG-COM numbers and blocks, I'm not totally sure what results I am looking for and what to do with them. Info seems to be sparse in these areas.

Rosstech forums and wiki are the best place to get this info. I really only use VAG-Com for convenience module changes and key coding etc and wouldn't like to give you the wrong answer.