Audi A4 B7 2.0 TDI misfire

[QuattroMark]

My A4 feels like it has a bad misfire - when being driven on the road I sometimes get a 'hesitation' then that goes away - when the car is stationary it is really noticeable, the whole car shakes.

On start up from cold there is a cloud of smoke ( not massive but its there) but the car starts no problem first time - on start up from hot sometimes it takes a couple of goes.

If when I am driving and the gearbox goes into kickdown (auto) there is a big black cloud comes out of the back!!

I pulled the codes with my VCDS and I got P0301 which is misfire cylinder 1 - I also looked at the live data on the injection quantities and cylinder #1 is out side the standard delivery rate at 2.96 mg/str.

I have just ordered a compression tester (hopefully here by the weekend) so I can check if there is anything wrong in that department - just don't want to shell out £500 for an injector that may not cure my problem.

Any thoughts?

 

Mark

 

[rbdazza]

compression test is a good call. are your injectors serviceable (I assume yours is a PD and not sure if they are)? that would be a cheaper and probably better option

[rbdazza]

other things to try:

1. air filter, replace it as a matter of course, theyre cheap

2. check EGR, is it functioning and is it clogged (take a peak into the inlet manifold whilst you are there too)

3. possibly turbo, you'd probably hear that though if it was on its way out

[rbdazza]

another thought, low compression should give white smoke, not black. still worth a check though. 

does it smoke when sat idling for a period of time? i mean a good few minutes? what colour is the smoke then if so?

[rbdazza]

sorry for spamming! looks like you can get PD injectors serviced. you could probably get them all done for not much more than what it cost for one brand new one.

not sure where you are in the country but i can recommend diesel bob up North, google him

[QuattroMark]

Hi Darren,

Air filter fuel filter have just been done - and the EGR and Turbo were replaced 2 years ago - suppose the EGR could be gunged by now though - will strip it down and clean it.

It doesn't really smoke while standing - just on initial start up and when its booted hard - if its just sat ticking over its barely noticeable.

 

One thing I didn't mention was that on initial cold startup its  quite loud - 'tractorish' as one of my friends commented! and then after about 15-20 seconds the engine tone changes - almost like some sort of valve/flap is operating.

I've used Diesel Bob before on my B6 - good guys!

 

Mark

 

[rbdazza]

what mileage is it on?

[rbdazza]

cold noise could just be down to the type of oil you use, but then could be related to a dodgy injector or timing being out 

[QuattroMark]

She's just about to come upto 225K!!! - gets well looked after - oil and filters every 9000 miles - generally bomb proof!!

 

 

[rbdazza]

at that mileage i'd suspect an injector then. there is of course the other common problem with those engines, cam lobe wear! 

[rbdazza]

have you had any problems with the oil pump?

[Trevor]

I would have suggested all the points that rbdazza has covered but also worth checking the leak-back on the injectors and see if number is any different from the others.

http://www.sealey.co.uk/PLPageBuilder.asp?gotonode=ViewProduct&method=mViewProduct&productid=13206&productdescription=diesel&productcode=&category=6&catgroup=161&catmicrogroup=1254&analysiscode=&requiredresults=16

There are other kits a little cheaper out there that will still do the job

[rbdazza]

good call Trev

[QuattroMark]

No problems with the oil pump Darren - and to be honest I did think about cam lobe wear but the noise is not constant, it changes....need to have a look at it really-

[QuattroMark]

I stumbled across an independent Audi specialist at the weekend - he took 1 look at my A4 and said that I needed the timing belt changing - he had seen this issue many times and went onto tell me EXACTLY what my symptoms were when the car wasn't even running - 'apparently' my issue is with the exhaust valve timing - you need to use something like VCDS to complete the timing belt install.

 

Anybody heard of this? - surely the exhaust valve timing cant be out on its own - only a change in the cam lobes could facilitate this?

Is there a function on VCDS that checks timing?

 

Mark

 

 

 

[rbdazza]

you can check and adjust the timing in VCDS. 

i would however be questioning why a new belt is needed, they either are in tact or they aren't. if your timing is out then get it adjusted with VCDS then go from there. when was it last changed?

 

[QuattroMark]

Hi Darren, I was under the impression that it was not possible to change the timing in VCDS - because it is a PD car - there is a Torsion Value measurement ( see below) which will give an indication if it is out - I believe there is a small amount of adjustment on the pulley which can bring this value back into tolerance- however, not had chance to see this yet so I am prepared to be shot down in flames!!

 

 

 

The Torsion Value of -0.5KW is within tolerance so it seems the timing is ok.

However, Injection Quantity is all over the place, cylinder 1 hit 2.99 mg/str at one point -

I checked EGR measurements, again they seem to be all over the place.

 

You can just see (before it faded away) what the specification should be at idle - its miles off. Possibly have a clogged EGR??

 

This screen shot shows how excessively out it is.

 

Finally did some Advanced measuring on the cylinders, you can clearly see cylinder 1 is wrong.

 

I'm going to do a Purge clean of the injectors to see if this helps - I'll also pull the EGR and clean it

 

Mark

 

 

[QuattroMark]

16 minutes ago, rbdazza said:

you can check and adjust the timing in VCDS. 

i would however be questioning why a new belt is needed, they either are in tact or they aren't. if your timing is out then get it adjusted with VCDS then go from there. when was it last changed?

 

The belt is coming up to 60K miles -

Just out of curiosity....how do you check and adjust the timing with VCDS?

 

 

[rbdazza]

i have no idea, never done it.

things i would be doing:

1. remove and clean EGR, put it back but leave it unplugged

2. do a leak off test on your injectors, i would say number 1 is potentially fubared

[QuattroMark]

So just an update to this topic - changed injector #1 cleaned out the messed up EGR and the car now idles really smooth - my only issue now is that when I start the car It sounds a little noisy, but relatively smooth - readings shown below: 

Take a look at group 3 - especially block#4.........

 

After about 4 minutes there is a noticeable change in engine note - and this is what I get :

 

For some reason the EGR duty cycle goes through the roof - as does block 2 & 3 - the car is still at idle @903 rpm - if I blip the throttle then the readings go back to around the same as on start up....after 4 mins it reverts back to the same as above.

 

Any ideas ?