audi 80 tdi 12 month problem

The message from "bigmick" contains these words:

Perhaps there's /also/ an intermittent ECU fault. Or, perhaps it sees the engine revs going up and down for no particular reason and says "Oi, that must be the ECU doing that".

Fix the air leak first, then see how you stand.

And for heaven's sake work out how to do capital letters at the beginnings of sentences and spaces after the full stops!

try a bit of clear pipe before the fuel filter , then you can see if it's the fuel filter casting (cheap down the scrappy) or the pipe to the tank

Probably because it can't work out what the hells going on either :-)

>

Thanks a lot guys i am going to try all of the above and will let you know. Thanks again Regards mick

Pete Smith (pete snipped-for-privacy@lethe.org.uk) gurgled happily, sounding much like they were saying :

No sane jury would convict.

Ok guys heres what ive done,ive bought a clear peice of pipe and connected it to the fuel filter and put the other end in a container of diesel.I then started engine and primed every thing up until all air had gone,engine sat sweet once all air had gone.Now reved engine hard and still loads of bubbles shot down the pipe the the fuel pump every time i reved it,so then went and got old type fuel filter the sealed type with just inlet and outlet and put that in place of audi filter to try again.I made sure all pipes were fixed properly so theres no leaks started her up and waited till all air had gone again,there was no air coming up the pipe from the can BUTagain when i reved hard there they were bubbles shooting down the pipe to the pump.what do i do next really cant work it out,hope some one has a clue regards mick h

What do you mean old type fuel filter with just an in and out? A petrol one? If it is a petrol one, get rid of it asap. Petrol filters are no where near good enough for diesels.

But as it's still drawing air, you'll have to keep working back along the inlet pipe, until you find the problem. My next move would be to check the fuel tank, especially where the pipes enter the tank.

Hello no its not a petrol filter it one like on the old escort diesels like a coke can with to stabs on the top,no need to go as far back as the tank yet as i said i had a pipe running from a can of diesel straight in to the filter and still got the same problem.Icouldnt beleive there were bubbles going to the pump after all that as it took me ages to sweat the pipes on to the stabs so i thought theres no way they are going to leak,and i also really cranked the pipe clips down aswell regards mick

Fuel filter should be fine then.

There are a couple more tricks to try. One is to cover any pipe connections with grease. The grease acts a temporary way of blocking any leaks, but it is a messy method. The other thing you could try, is to get an absolutely spotless container, put some diesel in it, and put the pump inlet pipe directly into it. You've got to make sure you don't get any dirt into the pump using this trick though.

Something worth mentioning is, what hose clips are you using? If they're Jubilee style clips, I have seen these bunch the pipe up around unions, and that bunching is enough to let air in. If possible, try and get some of the type with a nut/screw to tighten them (like the top of the three options at

as they prevent the hose getting bunched. If the problem is hose clip related, using proper O-clips (crimp clips) is the best long term solution.

hello guys right then where do i start,ive done all the above ive replaced all the pipes and used the proper clips and have now cured the air problem.There is now no air going through the system or pump even when i rev it hard,ive just had 30 mins outside stood with the car and it run lovley so i decided to rev it just to check again if any air was there and no none at all.But the engine did the same again started to run lumpy really puting the engine mountings to the test,i decided to crack one of the injecters and tighten back up and it went back to running smooth again, but 2 mins later was again running rough so now im stumped any ideas regards mick

Go & buy another filterhousing from the scrapyard (there's only aboout four types total so it doesn't have to be from an Audi) & try that, it might just be slightly cracked.

hello again why do i need another filter housing there is no air in the system now regards mick

Sorry, I though you said it had returned.

Hello duncan the engine is running rough intermitently but there is no air in the system do you think it could be the ecu now regards mick come on guys some one some where must know whats up its driving me mad

It could be, but it's pretty unlikely to actually be the ECU, check the grounding to it & the power connecters are clean first.

Thankyou Duncan wiil check those and let you know regards mick

Sadly it could be the ECU, but it is rare. If you've access to a decent multimeter check the voltages when it's running roughly on all the grounds to the sensors, unless you've got a spare ECU there aren't any sensible shortcuts. The other check is the fuel pressure at the filter, if the lift pumps sticking that can give you grief, although that's more likely to be an issue under load than idle.