1.9 Tdi, Loss of power and Missing/Thumping from engine.


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Mar 25, 2010
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Killarney, Ireland
My uncle called to me this evening with his B6 1.9 TDi (AVF) 130bhp quattro which isn't running right. It's covered 210,000 miles. At tick over and right through the rev range it sounds like it's running on 3 cylinders, there appears to be a "thumping" coming from the engine. When I had the pipe to the airbox off, the thumping was resonating loudly through it and when I had the intercooler pipe disconnected it was even louder, really booming (not unlike a blown exhaust). On driving the car it's down on power, but isn't so bad that you couldn't pass something, it's at about 70% of what it should be. I was thinking a faulty injector at this stage and presumed my VagCom would pick it up.

I ran the VCDS on it but no codes came up. I went into the measuring blocks (Engine / 13) to see how the injectors were performing and while the "Idle speed smooth running control" remained within tolerance, -2.8 to 2.8 mg/H they seemed to be all over the place. Approximate reading were Cyl1: -1.0, Cyl2: -1.5, Cyl3: 1.0, Cyl4: 1.1, on revving the car they didn't alter too much and never went outside tolerance.

I'm thinking camshaft wear or/and wear to the lifters at this stage, but before I go ripping has someone else come across this before. I don't think it's an injector failure as the VCDS should pick up on that. This problem appears to have started overnight.

Any help would be appreciated, thanks.
Can't really help you there myself other than say that if it was camshaft or lifter wear then it wouldn't appear in an overnight type of way..... has it had regular cambelt's fitted ??? i'm wondering if maybe it's slipped a tooth on the belt ?? though i don't know how close tolerance these engines are
Timing belt was last changed at 158,000 miles so it's not too far from a new one. I'll be having a good look at the camshaft and lifters this evening so while I'm at it I'll check to see if the timing is lining up as it should. I'd be thinking that if it slipped a tooth it would be worse than it is, but time will tell. I can see a dent being put in my bank holiday weekend already. :sadlike:
I would think this to be an injector fault, have you tried loosening the injector unions one by one and catching the escaping fuel while the engine's running to see if the knock goes?
Thanks for that George, I would have just skipped over it as I presumed that the VCDS should pick up an injector fault. I take it from your response that the VCDS wont pick up a fault like this.
He dropped the car up to me at lunch so I pulled off the rocker cover and I took a quick look at the camshaft. The cam lobe closest to the timing belt is badly worn. It appears to have worn about 20mm across the circumference of the cam lobe and the chamfer on the edges of the lobe are completely worn off in that area, this means that over a millimeter is gone off its lifting surface and the damage is probably the same on the lifter it's coming into contact with to open the valve. I'm going to now go on the basis that the camshaft and lifters (and bearings while I'm at it) will need to be replaced. I might aswell do the timing belt, tensioners and waterpump while I've the belt off.

The timing belt is no bother, but I've never replaced camshaft, lifters and bearings before. Anybody out there have experience on this? Is there anything I need to lookout for?
Did you do this mate? How did you adjust the fuel injectors?
Yeah, I did this alright. There is a bit of work to it but if your happy enough changing a timing belt you get on fine. The injectors don't need any adjustment if you're just replacing the camshaft, lifters and bearings.
Yeah, it fixed it alright. Just over 3000 miles done since and all going well.

Parts were €1100, that covered camshaft, lifters, camshaft bearings, timing belt kit, waterpump, oil, oil filter, air filter, diesel filter. And from the main dealer I got, the replacement bolts and gaskets.
ouch... not cheap then , glad you got it sorted though and at least now you have peice of mind that the topend is fine..... Good work :)
Camshaft, lifters, bearings and seal was €575. Could have got it cheaper online but couldn't afford to be waiting 5 days to have it delivered. And if there was something wrong it would take forever to sort out. The camshaft bolts (18 off them) were nearly €200, I've heard off lads not changing them but to me it's just not worth the risk as they are stretch bolts, again these would have been cheaper if I had got them in England or up the North.