2.0 TDi 140 PD - Rough idle and misfire...

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Nufab

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Hello all...

I have a 2005 A4 Avant, 2.0 TDi 140 PD (BLB engine), with 177,000 on the clock. I've had it for nearly 5 years and it's been great, but 6 months ago it developed a really rough idle. It now takes a while to start, runs rough for the first 30secs or so, and settles down to a smooth idle. Once it warms up, its rough enough when idling to shake the car.

It then will shudder under load in 4th, 5th or 6th when the engine is doing under 2000rpm. Its really violent if you accelerate hard. Above that it's smooth again. Again, this only happens when the engine is warm, when its cold it's fine.

Power is fine, car pulls really well to the redline.

I've had the flywheel and clutch changed in January as I'd thought this was the problem (and it did need doing, clutch was slipping a lot..) but it's not solved this side of things.

Basically the car is really nice but this is driving me mad.

I've read various causes, but not sure what it'll be. Any ideas are welcome! It's not been on VCDS, but I was intending to get hold of a cable and do a scan and check the cam timings.

Thanks,

Chris
 
I’m not an expert but maybe glow plugs ? Fuel filter block ?


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Nufab said:
Hello all...

I have a 2005 A4 Avant, 2.0 TDi 140 PD (BLB engine), with 177,000 on the clock. I've had it for nearly 5 years and it's been great, but 6 months ago it developed a really rough idle. It now takes a while to start, runs rough for the first 30secs or so, and settles down to a smooth idle. Once it warms up, its rough enough when idling to shake the car.

It then will shudder under load in 4th, 5th or 6th when the engine is doing under 2000rpm. Its really violent if you accelerate hard. Above that it's smooth again. Again, this only happens when the engine is warm, when its cold it's fine.

Power is fine, car pulls really well to the redline.

I've had the flywheel and clutch changed in January as I'd thought this was the problem (and it did need doing, clutch was slipping a lot..) but it's not solved this side of things.

Basically the car is really nice but this is driving me mad.

I've read various causes, but not sure what it'll be. Any ideas are welcome! It's not been on VCDS, but I was intending to get hold of a cable and do a scan and check the cam timings.

Thanks,

Chris
Click to expand...
I had a similar problem a while back and it turned out to be the alternator pulley . It's easy to check . Just get someone to start the car while you look into the alternator. And then get them shut the engine off while you look inside the alternator. If the inside of the alternator keeps spinning for a few seconds after the engine has stop it's fine. But if it stops dead with the engine it's the pulley seized .

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Sounds like fuel issue as above change the fuel filter cheapest thing to start with

If got VCDS check the flow on injectors, mine developt the same issue was one of the injectors was starting to fail.
 
I've had this exact issue with mine- changed the thermostat last week and afterwards it was idling really rough, difficult to start- turned out to be a crankcase breather pipe split at the back of the block, I must have disturbed it removing the Tstat- if you've had work done on your car recently, and it's been like this since, then I'd definitely check all the breather pipes etc.
 
Thanks guys, that's a good list of suggestions. I've got vcds cable coming so that may help... I like the suggestion about the breather pipe... I do most of my own maintenance so maybe I've knocked something by mistake.

The trouble with these cars is their complexity... various things could be at fault and most fixes are expensive!
 
Nufab said:
Hello all...

I have a 2005 A4 Avant, 2.0 TDi 140 PD (BLB engine), with 177,000 on the clock. I've had it for nearly 5 years and it's been great, but 6 months ago it developed a really rough idle. It now takes a while to start, runs rough for the first 30secs or so, and settles down to a smooth idle. Once it warms up, its rough enough when idling to shake the car.

It then will shudder under load in 4th, 5th or 6th when the engine is doing under 2000rpm. Its really violent if you accelerate hard. Above that it's smooth again. Again, this only happens when the engine is warm, when its cold it's fine.

Power is fine, car pulls really well to the redline.

I've had the flywheel and clutch changed in January as I'd thought this was the problem (and it did need doing, clutch was slipping a lot..) but it's not solved this side of things.

Basically the car is really nice but this is driving me mad.

I've read various causes, but not sure what it'll be. Any ideas are welcome! It's not been on VCDS, but I was intending to get hold of a cable and do a scan and check the cam timings.

Thanks,

Chris
Click to expand...
I have all these issues with my 08 2.0 TDI. It wouldn't start so the garage changed the flow plugs. It starts now but chugs for a few seconds. The car rocks slightly when idling. Had a 1.9 TDI before this 190k on the clock with no problems. Never known this before but when pulling away in 1st gear, there's no chance of fast acceleration, just seems like something holding it back.
 
I had very similar symptoms, shudder around 2k higher engine loads was worse. Worse when cold.

Turned out to be a failed injector. So vcds should give you a hand diagnosing it.

If you identify one injector as faulty on vcds, check the loom and be careful with the connectors they are rather brittle.

You could switch two injectors over and see if the problem follows before you punt for an injector they ain’t cheap.

I’m just having problems now too, limp mode, narrowed down to an actuator problem now. And my clutch is going, all comes at once doesn’t it!
 
Thanks for the suggestions... my cable hasn’t arrived yet so no progress.

I’d have thought if it was an injector then I’d lose top end power.. ditto if it was the injector loom or worn camshafts. Plus this is when it’s warm rather than cold, so I’m not sure it’d be glow plugs.

My google searches don’t really give a specific cause of this king of thing though, so if I do solve it I’ll be sure to come back to this thread and update you all. Meanwhile any further things to look at would be welcome!

My plan is to read any fault codes and check the cam timing, then check all breathers are intact and change the fuel filter and run some injector cleaner through... if that lot doesn’t sort it I’ll just set light to it :wtf:
 
I had a similar problem with my 2.0tdi it would feel like a misfire around 2000rpm, the car would judder sometimes violently, but would drive perfectly other than that.

Then the DPF blocked and the car wouldn’t start at all. I ended up having the DPF removed and the car re-mapped, this was the cheapest option at the time. I got the car back and it drives so much better than it did before but it still had this “misfire” at around 2000rpm but it actually felt worse than before. But I could sort of drive round it so I tried to ignore it.

I had the car serviced later that year and happened to mention it to the guy who ran the garage, he looked into and had a “specialist” look at it. He ended up blanking the egr valve, something which he said should have been done when the dpf was removed, anyway the car has been perfect ever since.
 
John Clutton... that sounds like 'limp mode'... mine did that when I blanked off the EGR valve, before I had the EGR mapped out.

So in light of some of the above suggestions, my car has the EGR valve present but blocked off and the engine map allows for this. It does not have a DPF.

My cable finally arrived, and I was able to get the car plugged into VCDS. On starting up, the car smokes and idles really roughly for about 30secs. I took a screenshot of some of the measuring blocks when I first started the car:

Immediate start


Then it settles down to a smooth idle...

Smooth cold


Smooth cold 2


I did these today while the car was cold. I had previously hooked it up to VCDS after my 30min drive home from work, when the car was really rough, but unfortunately the screenshot jpg corrupted itself! Basically though the 'idle stabilization' readings looked similar to the first image, with cylinder 3 at 2.99.

Anyone got any ideas? I know the torsion value is out but I'm thinking the main issue is that injector on cylinder 3. Not sure why its only a problem when it's warm though... maybe injector seals?

Cheers,

Chris
 
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I’m well aware of the BLB oil drive issue... I spent a week with it off the road while I removed the balance assembly and sent it off to be re-engineered with the longer hex shaft. That was over two years ago now; luckily I was able to stop the car immediately on seeing the warning light and get it recovered, and all was fine. Cost £200ish in parts to fix, where many people have spent thousands.
 
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Right then, its taken me a while this one... but I've taken the fuel filter off today, and the fuel inside is black. Not thick with oil, it looks clear as you pour it, but once it's in a jar it looks black. Clearly something is going on and I think it's the injector seals.

PLan now is to order some seals and bolts, and change the seals on injectors 2 & 3. I'd do the lot, but I'm wavering between "fix it" vs "being a one car family" at the moment, seeing as I rarely use the car, so I want to keep costs down. Still, I love tinkering so I'll give it a go and see how far I get.
 
OK, its taken ages to sort this, but it is now fixed. I'm not sure if anyone's interested, but I have seen so many similar threads on forums that never get updated with an answer, so I wanted to get this on here!

So, I removed injectors 2 and 3, and cleaned up the tips with carb cleaner. I replaced the seals, and I used some wet and dry paper to clean up the angled area that seals against the seat in the cylinder head. I then gave it all another clean to make sure I didn't get any crap into the engine.

I then bolted the injectors in with new stretch bolts. I reused the rocker hold down bolts, because they didn't appear to be stretched when I compared them to new ones.... As I'd bought a full kit of bolts, I now have 4 injector bolts and a set of rocker bolts spare in case this ever needs doing again! I then reset the lash on the injector rockers, and replaced the fuel filter for good measure.

Then it wouldn't start.... and the battery went flat.

After playing with a set of jump leads and cranking it for about 45 seconds, it fired into life, and sent a massive black cloud drifting down the street. So much smoke, I thought I must have broken something. Then I drove it, and it continued to smoke for about half a mile...

And then it settled down and drove really well. I got it up to temperature and gave it a thorough test. No rough idle, and no shuddering under load.

Basically, I'm euphoric.

I got it on VCDS just to show the difference my efforts made....

Hot1




So there we go. If anyone else has similar issues.... get it on VCDS to see if one cylinder is at fault. Then check to see if you've got oil in your fuel filter. If you have, its injector seals, and they're easy.

Cheers all,

Chris
 
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