HELP! Audi A3 2004 1.9 Tdi EGR Problem?!

[aman_]

Right so I have a hugely confusing problem with my car......its an Audi a3 1.9tdi 2004 8p with 95k on clock

A year or so ago the engine light came on so I checked it and it was the egr fault code p0401. Left it and didn't do anything for around a year because the car ran perfectly fine. A year on and the car all of a sudden started black smoking with a intermittent pause before getting normal boost and power. So I would pull away and I would get a drop in boost for about half a second and then all of a sudden the power would come shooting back along with a cloud of black smoke.

So I replaced the EGR... fully cleaned all the pipes and as much as I could of the intake manifold using mr muscle etc. Problem still there.....so I removed the egr vacuum pipe and blocked it off with a screw.....CAR RUNS PERFECT! So I decided to check all the vacuum pipes for any leaks etc and everything was all good.

Anyway so few months went by and I decided to try and fix the problem.....went and put the egr vacuum pipe back in the egr and tried driving the car and it wouldn't drive at all! just stalled when trying to pull off!!?? If i revved the car at stand still it wouldn't go higher than 2k.....and the revs were jumping up and down whilst revving (cutting out). Also was getting loadsss of white smoke out the back!

Ive checked everything I could think of, even checked air filter and replaced the MAF because I thought it was that, no change.

Someone please help!? One question.....is it ok to block the egr vacuum pipe off and keep the car running like that...? won't cause any back pressure and damage anything will it??

Thanks!

 

[SmithyAG]

Disabling the EGR shouldn't cause any long term problems. Ideally you'd want blanking plates installed but it should be fine without them.

It sounds like your current EGR valve is stuck open if it stalls when trying to drive away...

 

[aman_]

Disabling the EGR shouldn't cause any long term problems. Ideally you'd want blanking plates installed but it should be fine without them.

It sounds like your current EGR valve is stuck open if it stalls when trying to drive away...

Yeah will defo have to blank it off soon as I don't want a huge build of crap under the egr while its disabled.

and I doubt the egr valve is stuck.....its brand new! even the old one was fine i think....

I reckon its something to do with the vac lines or pressure lines....i just can't get my head around why the car is like dead when i plug egr vac pipe in....but when i block the pipe off the car is instantly perfect....?!

 

[SmithyAG]

Hmmm sounds like a VAC problem like you say, perhaps constantly pulling the EGR valve open?

Any way you can see what the valve is doing whilst car running? Removing the hose to it and using a mirror maybe or take a photo with your phone if you can't see in?

 

[aman_]

Hmmm sounds like a VAC problem like you say, perhaps constantly pulling the EGR valve open?

Any way you can see what the valve is doing whilst car running? Removing the hose to it and using a mirror maybe or take a photo with your phone if you can't see in?

I could try yeah, what should it look like at idle then? I have a feeling its something else and nothing to do with the egr. Defo something to do with the vac lines that is then giving some false reading to the ecu that is causing my engine to run in some crazy limp/dead zombie mode where it won't even drive!!?? I feel as if its something small and simple that will fix it.....confused!

 

[SmithyAG]

I can't think what would be causing it when the EGR vac line is disconnected.

It sounds like no vac to the turbo if you're getting smoke out of it, as you'll be driving with no/little boost, hence too much fuel and that equals smoke out the back, usually grey/black.

Could probably do with getting certain things logged, like actual vs requested boost etc