Poor idle on warm up

[eddiek]

My 2007 (B7) 2.0 TDi 170 which I have only owned for a month now is having a problem. The car starts fine and runs /drives fine for a few minutes then if I have to stop in traffic etc it will go into a lumpy idle mode and only seems as it is running on two cylinders.Can hardly pull away without revving the guts out of it and will only rev to 3000. Then when the engine temp warms up and gauge reads normal all is well, the car runs as sweet as a nut and will tick over as smooth as you like.
If I can drive away and not have any stops for a couple of miles the car will perform as normal and runs very smooth. It is only in the initial warm up period this is happening and cant quite seem to figure out the cause. Has done 130,00 with a full dealer history. Engine code is BRD. Will be trying the fuel filter and the injector loom to see if any improvement. Any advice appreciated. Thanks.

[Crasher]

Before you do anything, have it fault code read. These symptoms can be an early indication of an injector on its way out.

[eddiek]

Sorry, should have posted that I had done a scan on VCDS and no faults found. ?

[Crasher]

The only thing you can do is ask the dealer to change all four injectors. I did one two weeks ago that had a terrible idle the previous time I drove it when I fitted a new flywheel/clutch and balancer shaft assembly. It had been fitted with one new injector by the dealer about a year ago after it cut out so we fitted the other three. I found all the injectors were all incorrectly set up (the previous new one was two full turns out) and with three new injectors properly set up it idled perfectly and had significantly more power.

[eddiek]

Thanks for that crasher. The car is booked in at Audi main dealer next week for a check on the injector /loom problem as so many have been suffering from, and was my first thought regarding this problem. I have actually got Audi UK involved as obviously vehicle is out of warranty now. But taking advice from others on this forum decided to speak to Audi UK and they have advised to take it to main dealer. Hopefully they will diagnose injector/loom problem . Will post results here ??

[eddiek]

I changed the fuel filter and the contents were quite dark/sooty looking . The filter had done 20,000 according to service history. Is it normal for the Diesel to be this colour in bottom of filter?The top of filter contents were a lot cleaner but got darker as I poured the lot out .1495614957

[Crasher]

There is often a layer of silt at the bottom of the canister, especially if the last time it was changed the mechanic did not empty the canister and clean it.

[eddiek]

There is often a layer of silt at the bottom of the canister, especially if the last time it was changed the mechanic did not empty the canister and clean it.


Yes exactly right but this vehicle has a throw away canister type so gets totally replaced each time.

[eddiek]

I have replaced the injector loom today but has made no difference. I should add when vehicle is warming up and idling it is emitting a lot of blue smoke. then take it for a run and all clears when up to normal temp.
Do you think this is the tandem pump leaking oil into fuel, bearing in mind what colour diesel is when I removed from filter. Reading the Piezo Injector failure sticky post also sounds a bit familiar.
a8 tech where are you can you help/advise ?

[Crasher]

The tandem pimp failures I have seen make the diesel go very black, it contaminates the whole system including the tank but blue smoke says to me it is burning oil although on a diesel oil being burnt usually shows itself as grey smoke.

[eddiek]

Yes that's what I thought, actually come to think of it... At first it is a greyish colour and then turns blue and then it`s gone, no smoke at all not even black ???

[Crasher]

The smoke gradually disappearing is odd and suggests it is over fuelling when cold.

[mike4211]

I have same car (BRD engine) on 100k, all 4 injectors and loom replaced since 60k, and have exactly the same issue on warm up, which I think is due to overfuelling (stinks of part-burnt diesel). I checked my fuel filter and definitely no oil present, and no fault codes showing. The problem started before the injectors were replaced by Audi, but the new injectors and loom have made no difference. I wondered if a faulty EGR valve or swirl flap actuator might be the cause, but not sure how to test...? Has your car been in to Audi for testing yet?

[patrickhorton]

I started a similar thread on this a year or so back. same 170 BRD engine same symptoms with 50-70deg on temp guage - stinky blue/grey smoke, lumpy idle. Perfect running when cold or normal temp.
I have a new EGR (after old one stripped a cog), cleaned intake manifold a swirl flaps, checked EGR cooler; none of these fixed the lumpy idle. Oil consumption is real low - about 1litre/10k miles.
All I can say is it is EGR related and is probably down to a very finely set ECU coding to maximise EGR. Perhaps some engines can cope and others not just down to manufacturing tolerances or something. A8 tech called it EGR bounce.
My solution has been to live with it. The way my journeys plan out, the engine rarely idles till its hot so I don't notice too much. That said, it is still the one big niggle I have with this car. I am sure Audi could have programmed this out if it had been a bigger issue but I guess it never will be.

My thoughts on the various suggestions about faulty parts such as injectors or tandem pump or filters are that they would not show up just at one particular temp range and then be perfect the rest of the time.

Patrick

[eddiek]

Mines is going on on Tues 11th so will see what they say. Looks like the EGR valve has been replaced on mine as it looks quite new, but can not say for certain as no record of it.

[eddiek]

I started a similar thread on this a year or so back. same 170 BRD engine same symptoms with 50-70deg on temp guage - stinky blue/grey smoke, lumpy idle. Perfect running when cold or normal temp.
I have a new EGR (after old one stripped a cog), cleaned intake manifold a swirl flaps, checked EGR cooler; none of these fixed the lumpy idle. Oil consumption is real low - about 1litre/10k miles.
All I can say is it is EGR related and is probably down to a very finely set ECU coding to maximise EGR. Perhaps some engines can cope and others not just down to manufacturing tolerances or something. A8 tech called it EGR bounce.
My solution has been to live with it. The way my journeys plan out, the engine rarely idles till its hot so I don't notice too much. That said, it is still the one big niggle I have with this car. I am sure Audi could have programmed this out if it had been a bigger issue but I guess it never will be.

My thoughts on the various suggestions about faulty parts such as injectors or tandem pump or filters are that they would not show up just at one particular temp range and then be perfect the rest of the time.

Patrick
Patrick, my gut feeling is a software/ECU glitch but would like to know if there is an update that can be installed by dealer. Read some where on a forum there was a ECU update but just can`t remember where and if it was a similar problem. I have read so many different posts on the 170 engine my head is spinning with all the info.

[eddiek]

This was the post I am referring to http://www.pistonheads.com/gassing/topic.asp?t=791581
Interesting reading ?

[eddiek]

My Audi dealer has fitted 3 new injectors of the latest type, apparently one had already been replaced previous to my ownership. The car seems to run a lot better now and am monitoring it closely.Will also be keeping an eye on the fuel colour in filter to see if it gets any darker as still seems a bit smelly when idling. When cold it can still be a bit sluggish on initial pick up for a few minutes but as long as it does not get any worse can probably accept that is as good as it gets. The total bill was picked up by Audi UK and the level of service I got from Edinburgh Audi was excellent.