A4 2.0 TDI 2006, Misfire, Blow Back Noise, Lack of Power, Help please

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Hi All,

I have a 2.0 TDI A4 Cabriolet, 2007, Engine Code BPW, 6 Speed Manual.

The problem started when I started her up on Wednesday lunch time and there was a sort of thumping noise coming from the engine area. After further investigation the noise is coming from the air intake where the engine seems to be blowback. See vid below hear:

http://dl.dropbox.com/u/38150502/A4 Misfire/Picture.MOV



You will see that although there is the blowback noise there is no shake or judder indicating a misfire. When driving the car apart from the obvious blowback noise increasing under more engine load, there is lack of power and an obvious misfire when accelarating for example from 60 mph +

Following this I called the AA man who confirmed there is some sort of blow back from the exhaust system into the intake manifold. We suspected it could be the EGR valve or possibly a bent intake valve.

I have carried out the following to diagnose the problem, unfortunately with no luck so far.

0: Checked with Vagcom: No fault codes

1: EGR Valve: Removed and cleaned EGR valve, it was dirty but still functioning. (see pictures below)

http://dl.dropbox.com/u/38150502/A4 Misfire/Picture 003.jpg
http://dl.dropbox.com/u/38150502/A4 Misfire/Picture 004.jpg
http://dl.dropbox.com/u/38150502/A4 Misfire/Picture 005.jpg

2: Blocked the EGR with a blanking plate at the flange between the EGR cooler and intake manifold (At Item 19 in link below)

http://dl.dropbox.com/u/38150502/A4 Misfire/Exhaust gas recirculation system - engine codes BKE%2C BPW%2C BRB and BRC.pdf

3: Compression test on the engine - This is a bit of an iffy one where the compression tester developed a leak during the test, Cylinder 1 & 2 both reached 400 PSI, when we did 3 & 4 the compression test fitting broke and only got 300 psi on cylinders 3 & 4. When we repeated the test on 1 & 2 we got 300 psi. (300 PSI is still within the limit according to ELSA. (document link below)

http://dl.dropbox.com/u/38150502/A4 Misfire/Checking compression - engine codes AVB%2C AVF and AWX.pdf

According to Elsa the compression test on a BPW engine should be done using diagnostic equipment, is this on Group 13 on the ECM ? Showing the injected fuel quantity to detect an imbalance ? (Document below)

http://dl.dropbox.com/u/38150502/A4...sion - engine codes BKE, BPW, BRB and BRC.pdf

I have just ordered a compression tester which should arrive in the next few days.

4: Disconnected exhaust system from turbocharger to eliminate the chance of a blocked exhaust and or DPF (even though showing as not blocked on Group 75 Vagcom). Disconnected from Item 7 in link below

http://dl.dropbox.com/u/38150502/A4 Misfire/Exhaust system with particulate filter.pdf


5: Glow plugs: Removed and checked, all seem to be the same colour which indicates all cylinders are firing well. See pic below and correct me if I am wrong:

http://dl.dropbox.com/u/38150502/A4 Misfire/Picture 007.jpg

(Left to right, Cylinders 1 - 4)

6: Turned engine over with glow plugs removed to see all injectors are delivering fuel. I could not see any noticeable difference between the sprays, see vid below

http://dl.dropbox.com/u/38150502/A4 Misfire/Picture 008.MOV



7: Checked injector / pump rod adjustor screw according to procedure below, I found injectors 2 and 3 were 1/2 turn loose. Still did not help

http://dl.dropbox.com/u/38150502/A4 Misfire/Removing and installing unit injector.pdf

8: I disconnected the injectors individually to rule out if one of the injectors is not working. Upon disconnecting each injector there was a considerable change in engine noise and noticeable misfire. Indicating that all of the injectors are working. Also at no point did the blowback noise stop.

9: Filled tank with injector cleaner and 20 litres of V-Power and took the car on a 50 Miles run. No difference :-|

10. Disconnected air intake hose at inlet manifold: Can definitely feel the "blow back" from the intake manifold suction.

So here we are, I have asked a number of mechanics for their opinions and the only things I can think of are:

- Bent Intake Valve: To be confirmed with compression tester, however there is no smoke and engine is not shaking or misfiring
- Cracked Intake valve seat: ? Only be checked once head is off
- Leaking Head Gasket: To be confirmed with compression tester, but the pressure on all 4 cylinders is still 300psi which is above spec.
- Damaged Injector Nozzle, where the fuel is not atomizing and only spraying down causing poor combustion. However the vid I posted shows a similar spray. Maybe I should get the injectors checked ?
- Failed seal on injector: however this would result in blowback in the rocker cover and not intake manifold..

I have also read this document below which details how the injection system on the PD engines works.

http://dl.dropbox.com/u/38150502/A4 Misfire/VW_TDI_with_PumpeDuse.pdf

Any help, views, comments and corrections are welcome. Thanks in advance :)
 
Last edited by a moderator:
Hello mate,

I had a similar issue with my Audi A3 2.0 TDI 140, it sounded the same, took it to Audi expecting a good raping, but they had the same problem with another car a few months ago, just turned out to need a new fuel filter!

I done the whole v power, injector cleaner stuff too

Worth a try, the filters are expensive.
 
Listening to your video, it sounded exactly the same, I thought something was wrong internal to the engine, but it just turned out to be the filter.

I meant to say the filters aren't expensive, sorry hadn't had enough coffee by then!
 
Yeah it was perfectly fine, then just started marking the same noise as yours, it was very hesitant when driving and revving.

How did you get on with checking/changing the filter?
 
i would have said fuel filter mate but if you have checked it...
 
hi krumz, have similar problem with mine, was intermittent at first, would be ok one day next blow back through filter, then it would occour on start up but go as you drove off down road. because of this situation i ruled out inlet valve problem, suspected egr fault, but after speaking to an indie, he didn't think it would be, havent had a chance to investigate properly, but feel it could be a sticking hydraulic tappet holding a valve open, the indie did say they'd had no problems with these 2.0 tdi but all the symptons make me think this may be a good place to start. let me know if you find anything. thanks ron.
 
Hi Ron,

It's a pity I didn't see your reply earlier !!

Today:

The compression tester arrived and I did a compression test,*
Cylinder 1: 500psi
Cylinder 2: 510psi
Cylinder 3: 500psi
Cylinder 4: 510psi

So all at around 35bar

I then moved onto removing the inlet manifold, disconnecting the injector wiring loom and turned the engine over, all the cylinders were sucking but no2 was puffing back as well as sucking.

Reconnected the injector loom and started her up, definitely could hear the blowing back and popping coming from no2. Also found that there was no carbon buildup on the inlet manifold and cylinder head ports on cylinder no 2. Indicating the blowback is burning off the crap in the inlet.

Took the front end off and checked the timing. All ok

So ended up doing what 2 AA technicians, 8 mechanics and 3 engineers said it was and removed the cylinder head (regardless off the compression test being ok)*

Unfortunately have found nothing, no cracked valves, valve seat is ok, piston is ok, head gasket and mating surface marks show no indications of passing, the only thing I found is there is no carbon buildup around the outer circle on cylinder 2 inlet valve, indicating the edges of this valve are getting hot.*

(yes should've believed the compression test)

The only thing I can think of now is one of the injectors is injecting diesel prematurely, causing the issue.*
Have you read the pd engine document on my original post?*

So for now I have to get the head skimmed and get the injector tested!!
(and buy lots of parts, might as well do the belt, water pump, tensioners etc)*

Ron: what is your engine code ? How many miles ? Can you get the Inlet manifold of and check which cylinder is blowing back ?and swap the injector over and see if the problem persists.

Where abouts are you in the uk ?*

Look forward to hearing back ...
 
hi krumz, no havn't read your original engine document. engine code is BPW 018485 mileage approx 105000. haven't had time to start on engine yet, [weather not helping] would have thought if injector was pre injecting, we would have had more of a 'diesel knock'. i live in essex, Cheers ron
 
Hi Ron,
I appreciate what you're saying about injector knock, but what else could it be as the head "looks" fine, going to get that stripped and pressure tested)

Unless it is a sticky valve as you mentioned earlier, but wouldn't that mean it would misfire and smoke ?

I am taking cylinder 2 injector to get tested tomorrow, let's see what the outcome is...(if there's something wrong I'll get the rest tested)

Ill try and post some pics up tomorrow.

Let me know if you get round to doing any diagnosis on yours...
 
hi krumz, yes i would agree you do normally get misfire and smoke, but i've had valve seating problems on commercial diesels and you dont always get a distinct missfire, modern electronic controlled systems can compensate for minor irregularaties, although there is normally an increase in exhaust smoke, mainly black, caused by the incomplete combustion. its strange that your getting even compression figures. will be interesting to see what comes of the injector test.
 
Hi Ron,

Progress at last !!! I took the injector for testing (Carwoods) and they found that it was perfectly fine !

Took the cylinder head to a local machining shop in Rugby (where I work) and after a bit of investigation he found that the exhaust cam on no 2 was worn !! Not sure by exactly how much but will get the exact readings tomorrow (looked like 5mm)

He did a quick vacuum test on the No 2 Inlet valve and found that it wasn't sealing very well, however there were other valves on the head which were worse.... He said it could be due to debris in the seats causing them not to seal, so will check them properly

So here we are for now, it may be possible that all exhaust gases were leaving cylinder completely due to the exhaust valve not opening up fully. And these were blowing back out the inlet. I say this because if the inlet valve was passing the compression test would have not been good.

More news tomorrow......
 
hi krumz, very interesting, surprised we havn't heard more of this from forum members, we cant be the only two. what oil grade have you been using? what was the outcome on your cam? have the followers suffered? have you priced a kit? ron
 
Hi Ron,

Yes surprising indeed, especially as it seems as a common problem in the link I sent above.... I have been using Quantam Long Life 5w-30 from the dealers so cant be the oil. After chatting to the engineers doing the work on the head his comments were that it was not oil starvation as it was only one cam that suffered and the camshaft bearings are fine !
Hence must be defective cam which was not hardened correctly or an inclusion on the hydraulic tappet.
One lifter has a hole in it which explains where the debris came from that scoured the camshaft. The rest seem fine

Pricing:
Recon Head off ebay £475 - not going to buy that
Clean, Skim, cut valve seats, cut valves, pressure test - £200.00
New camshaft (eurocam)- £160.00
New Hydraulic tappets - £8.00 each (Im getting all 4 changed)
Cylinder head gasket gasket set with bolts - £82.00

All the above are plus vat.

Im also going to change the cambelt, waterpump, all the o-rings, injector seals and tensioners and pulleys on the engine. So Im looking at around £800.00 just for bits !!

I suppose you don't need to take the cylinder head off so you could get away with the camshaft, lifters and cambelt. If your planning on attacking it let me know and I'll send you the procedures off elsa. Also keep your camshaft and lifters as I'm going to send a complaint to Audi

Can send you the spreadsheet if required.

Have you had the rocker cover off yet ?

Pics as promised:

Worn exhaust cam:
http://dl.dropbox.com/u/38150502/A4 Misfire/Worn Exhaust Cam.jpg

Good Exhaust cam:
http://dl.dropbox.com/u/38150502/A4 Misfire/Good Exhaust Cam.jpg

Broken hydraulic tappet:
http://dl.dropbox.com/u/38150502/A4 Misfire/Kaput Hydraulic Tappet.jpg
 
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hi krumz, not had chance to start on audi yet, still have 3.0 tid saab stuck in my garage which has been more trouble than the audi ever has been, but thats another story. do you know if any of the vw owners managed to get recourse from vw? if so it may put us in a better posistion to get help from audi. i would appreciate the spreadsheet and i,ll keep all parts i replace. thanks ron
 
sorry, forgot to say, whilst reading through the cam wear article i noticed they didn,t include the BPW engine, did vw not use this unit or did vw use different engine codes?
 
Hi Ron,

I have not come across anyone who has any luck from the dealers with the worn camshaft issue. When I put in BPW on Elsa it only gives me the option for A4 so assume this engine codes only relates to Audi's. What I do know is the same camshaft is used in many 2.0 PD engines...

What is your email address, Ill send you the spreadsheet on there.

My new camshaft and hydraulics tappets have arrived, head should be ready tomorrow !!
 
hi krumz, as always they dont want to admit they had problems or cheapskated on the parts. e-mail address is RKJLITTLEFIELD@BLUEYONDER.CO.UK. did you buy oem parts or pattern? do you know if the cam has been improved? hope all go's well with the rebuild. cheers ron
 
hi krumz, how's it going with your rebuild? managed to find time to remove rocker cover this morning, and there it was number four exhaust lobe worn excessively, (haven't seen one this bad since the old ford ohc units used in the seventies) i'm amazed that no other lobe showed signs of wear. anyway thanks to you its saved me a lot of time and money, can now organise parts and carry out repair as soon as possible. p.s did you have tools to extend out front carrier or did you make them, if so can you tell me thread size and diameter and length of shaft. thanks ron
 
hi krumz, whilst looking through web to find cam prices, i found a website which i think is american called the tdi forum. of which there was a post about cam failures and warranty, this had a link to a german website called AUDIZINE.mobi. ( i dont know how to give you a link to this site) anyway they say audi have extended the warranty on camshafts to 120,000 miles or ten years on chassis range ;
WHU.....7K013458 - 7K037815 although mine dosn't fall within this range i will be calling dealer in morning to try and find out more, there is also a contribution allowance for any work already carried out, like yourself. hope this may be of help to you, i'll let you know how i get on with stealer.ron
 
Hi Ron,

Sorry for the late reply, been too busy getting the car rebuilt. (Done now !). I used OE parts for everything but the camshaft, hydraulic lifters, camshaft seals, cylinder head bols and head gasket set (these were supplied by the person doing the rebuild.
Attached list of parts and prices from TPS, ECP and GSF (trade)

http://dl.dropbox.com/u/38150502/A4%20Misfire/A4%202.0%20TDI%20Parts%20List.xlsx

Glad you managed to diagnose it without taking the cylinder head off !! Oh well I'll carry on looking at the bright side that I got my valve seats cut and increased the sealing lol.

I did the work in my uncles workshop who already has a couple of long bolts to hold the front panel. Are you talking about item 5 in the document below ?

http://dl.dropbox.com/u/38150502/A4 Misfire/Exploded view of lock carrier with attachments.pdf

I know it was a 12 or 13mm head size, so assume it would be a M10 bolt ?

Great work on finding out about the warranty, I will have a look at mine as soon as I can. I have zipped all the procedures that I have used off Elsa (in the link below). Will send you an email with my number if you need to give me a shout.

http://dl.dropbox.com/u/38150502/A4 Misfire/2.0 TDI BPW Workshop Manual Document.zip
 
hi krumz glad you've got yours running. i think i may have been a bit hasty with the warranty item, after looking more in depth at the website, it appears its the 1.8 and 2.0 t engine that has had problems with worn cams and these are the units that the extended warranty has been offered. so sorry for misleading you, although i'll keep looking. audi customer services and stealer knew nothing of extended warranty on our problem. thanks for info. cheers ron
 
Hi Ron,

How goes? I went to the Audi dealership on Monday and spoke to customer services (who have no technical appreciation of engines). The approach I have taken is that I am asking on a root cause analysis to why the problem is occurring. They initially said that they will get a mechanic over to comment on it, but came back and said that he will take pictures and get someone to email me. Lets see what they say.....

Would be useful to get some pictures of you camshaft.
 
hi krumz, no problem, now mine's stripped out i found No 4 exhaust cam follower worn right through and NO 1 showing signs of wear, cam has excessive wear on No 4 exhaust, as expected, but very little wear on No 1. it may be that the followers wear first then the cam. send me your e-mail address and i'll take some photo's. cheers ron
 
hi krumz, no problem, now mine's stripped out i found No 4 exhaust cam follower worn right through and NO 1 showing signs of wear, cam has excessive wear on No 4 exhaust, as expected, but very little wear on No 1. it may be that the followers wear first then the cam. send me your e-mail address and i'll take some photo's. cheers ron

Hi Ron, sounds about the same as mine, for some reason no 1 also showed slight wear too.

Ive heard a tappety noise coming from my engine, took the rocker cover off and four no 3 exhaust and inlet are showing slight signs of wear :-/ !!!! The chamfer is worn off the top off the lobes.
As you'd expect very annoyed, going to investigate further ! Again !

Khurrumsattar@hotmail.com
 
hi krumz, sorry to hear that, how many miles have you done since you put it back together? it seems odd that you have wear already. have you spoke to cam suppliers? keep in touch. ron
 
hi krumz, sorry to hear that, how many miles have you done since you put it back together? it seems odd that you have wear already. have you spoke to cam suppliers? keep in touch. ron

Hi Ron,

Ive done 1300 miles since the rebuild. Following my last response I had to do a lot of driving so just went for it. Since the long drive the tappety noise has gone. I spoke to the engineering firm that rebuilt the cylinder head who advised me it could have been a temporary oil starvation issue (blockage in oil galley). Either way he has said to monitor the wear and if it is getting worse he has offered to replace the camshaft and lifters again, (reasonable but I still have to do the work !)

As for quality wise it is a Eurocams camshaft which is supposedly of good quality. Hence I think it is the oil issue. I will inspect again this weekend and take some measurements to compare against.

I had Audi on the phone again today who said they will be speaking to the local dealership about taking my camshaft in for further investigation..... (would be useful to have those pics when you get a chance mate, to stop them saying "Oh its a one off issue)

Hope you car is coming along well....
 
Hi Ron,


I heard back from Audi and they basically advised me that they have "NEVER" come across this issue before and that if I want help in identifying the root cause I should book the car in. (No help then)


So far covered 2500 miles and took the rocker cover off to have a look, the camshaft wear has progressed which is alarming ! I have measured the lobes and found the following heights


1 - 60.7mm stepped
2 - 61.0mm stepped
3 - 60.2mm stepped
4 - 61.4mm
5 - 61.3mm steped
6 - 61.3mm stepped
7 - 61.3mm stepped
8 - 61.2mm stepped

The height on the unworn lobes on the genuine camshaft was 62.1mm

http://dl.dropbox.com/u/38150502/A4%20Misfire/Worn%20Lobes%202500%20Miles.zip


The engineering guy who did the work on the cylinder head and supplied the camshaft has been kind enough to offer to replace the camshaft and lifters (parts only) so I will be changing them this weekend.


In regard to finding out why it is wearing, the only thing it points to is lack of oil and the oil pump is faulty, however contradicting this is that the oil pressure alarm is not coming on and the engine is not making a "tappety noise" which would be the case if the oil pump is gone !


Any ideas ?
 
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I know this thread is a little old but looking at the pics I suspect that the cam followers(buckets) have siezed in the cylinder head (they should spin quite freely) this in turn has worn the cam lobe, if you look you will see that the cam lobe sits offset on the follower this so that in operation the follower spins... otherwise the cam lobe and follower just grind themselves to bits..

Regards

Adrian
 
i changed the cam/tappets on an "arl" 150 tdi mk4 golf two weeks ago. sounded exactly the same as the video posted above. had done just 90k. the cam had worn thru one of the tappet crowns. and 2 others were on their way too.
as these a splash lubricated and the oil pressure was spot on it cant be anything other than just crappy oil.
yes the tappets were all free to turn in the recesses in the head.

we used all parts from tps.
 
I know this thread is a little old but looking at the pics I suspect that the cam followers(buckets) have siezed in the cylinder head (they should spin quite freely) this in turn has worn the cam lobe, if you look you will see that the cam lobe sits offset on the follower this so that in operation the follower spins... otherwise the cam lobe and follower just grind themselves to bits..

Regards

Adrian

Hi Adrian,

Thanks for the input, however the followers were free to move when the cam was removed.

I have replaced the cam and followers again and done a 5k miles, all seems in order now. I feel poor fitting by the engineering company / oil way blockage was the cause of the second failure...
 
i changed the cam/tappets on an "arl" 150 tdi mk4 golf two weeks ago. sounded exactly the same as the video posted above. had done just 90k. the cam had worn thru one of the tappet crowns. and 2 others were on their way too.
as these a splash lubricated and the oil pressure was spot on it cant be anything other than just crappy oil.
yes the tappets were all free to turn in the recesses in the head.

we used all parts from tps.

Hi Murran,

Just for reference how much was the cam from TPS ?

Thanks
 
hi krumz, hope your car is still running ok. had another member e-mail me about the same problem with his car, a 2007 cabrio, 2.0 tdi having done about 95k, he'd approached dealer and customer services, but as we know, they didn't want to know. his one had also burnt top of piston, was yours o.k? it appears to be milage related, what had yours done? its strange it only appears to be on cabbies! thanks ron
 
I may have missed that you already have checked this but if not I would strongly suggest checking the aluminium plugs have not fallen out of the end of the swinging arm shafts as this causes a lack of oil pressure to the top end which can cause premature cam wear.
7379346494
 
I may have missed that you already have checked this but if not I would strongly suggest checking the aluminium plugs have not fallen out of the end of the swinging arm shafts as this causes a lack of oil pressure to the top end which can cause premature cam wear.
7379346494


Thanks, I did check the cam after 2000 miles and all seemed ok, however I will inspect the rockers too. Much appreciated
 
Hi Murran,

Just for reference how much was the cam from TPS ?

Thanks

i believe it was knocking on £500 if memory serves. tappets were nearly £20 each. other bits too like the gasket for the tandem pump etc.
cant remember exactly. final bill was well over £1k.
 
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