Audi 80 tdi juddering bucking jerking

[mangojuice]

My '95 Audi 80 Avant TDI had quite severe jerking right on 3000 revs and gradually got worse dipping into the lower rev range. I could either drive through it or slack off to come out of it. Turned out to be a faulty microchip on an injector and I've haven't had any problems since. As far as I can remember, the cost was somewhere around £230-£240 with the injector making up the bulk of the cost. I think the injector was about £190 on exchange. One way or the other, I hope this helps.

[azimnazir]

I have had the same problem on my 80 TDi estate on a 95M. So far, I have changed the following;

Timing belt, twice
Fuel filter,
Engine mounts
Gearbox mounts,
New glow plugs,
used fuel pumps TWICE,
New power steering rack,
New camshaft pulley,
New rear brake disc,
Engine rebuild,

Tried everything that other members have posted here, no joy and STILL the damn thing judders! This has has been a money pit from the day I bought it. I am guessing flywheel? I am determined to win this war, but the piggy bank is thinking otherwise. Has anyone got any ideas what it might be???

Desperate now!

Azim.

[allan_audi]

The problem is most definately down to the injection pump and specifically iron particles building up inside. You need to desolder the pump connections to get to them.

It is quite expensive to have re-built and there are several DIY articles regarding cleaning them out. I'll try and remember where they are, unless someone else can tell us quicker!!

There is also the much easier mod of removing the VSS signal from the dash to the ECU if you need a quick fix.

[audijay73]

I cut the blue and White wire and adjusted the actuator on the turbo and blanked the Egr valve sorted it but every now and then it used to hunt on idle but to be honest I was using 100 percent bio diesel . I wish I still had the 80 instead of an a3 pd
Hope this helps good luck jay


And it's true the swarf build up inside the pump is the problem from what I can understand the throtle arm moves on a brass plate a bit like a scalectrix controller if you see what I mean

[azimnazir]

Many thanks for your advice... I guess I will use my AA parts and labour policy to try and get this sorted out. I will keep you all posted no doubt because from what I see...260+ comments on this and no one is closer to a definite resolve. Everyoine seems to be trying different solutions which works for them.

For me, a process of elimination has brought it down to either Pump, Injector or Flywheel(?)

regards,

Azim.

[allan_audi]

Many thanks for your advice... I guess I will use my AA parts and labour policy to try and get this sorted out. I will keep you all posted no doubt because from what I see...260+ comments on this and no one is closer to a definite resolve. Everyoine seems to be trying different solutions which works for them.

For me, a process of elimination has brought it down to either Pump, Injector or Flywheel(?)

regards,

Azim.

Have you tried removing fuse 12?? (I think its 12 for the dash). This stops the VSS signal getting to the ECU and disrupts the feedback loop causing the juddering. Obviously don't try permanently because you lose the speedo, but its quick way to check if you're onto the same problem. If this stops the problem, I'm 99.9% certain its the pump. I wish I could find the link to the webpage for clearing the pump.

[micheal balbrig]

Many thanks for your advice... I guess I will use my AA parts and labour policy to try and get this sorted out. I will keep you all posted no doubt because from what I see...260+ comments on this and no one is closer to a definite resolve. Everyoine seems to be trying different solutions which works for them.

For me, a process of elimination has brought it down to either Pump, Injector or Flywheel(?)

regards,

Azim.

The problem with the swarf in the fuel pump can be improved immensly by cleaning out and using compressed air to try to blow the swarf out.
Your problem may be different as you have said that you have already changed two fuel pumps.
It is unlikely that all were faulty, or at least there should have been some differences noted.
Did you read fault codes.
Number three injector can go faulty, but I think it should show as a fault.
The fault with the swarf in the fuel pump in my case showed up as a violent jumping / jerking at abour 1500 revs but would dissappear
after revs built up further, it could reappear in a milder form in high gear either while driving,again could be overcome by driving through
the problem by higher revs. It could also happen while slowing down.
I took my pump apart and cleaned it out, but I would not recommend it as it is very tedious and possibly unsafe.
The simplest method is to clean it. I think it was Acmo who wrote an article after he cleaned his out, I did not see it as I think you had to apply by e mail for his instructions. You wil probably find it back in the earlier posts.
Good luck with finding your problem
Regards,
Michael.

[acmo]

This is what I put together after replacing my pump I thought I would investigate and sure enough like a few guys have said, its swarf.
https://docs.google.com/viewer?a=v&p...thkey=CKPvnvgL

Hope it helps

Ben

[arderra]

Hi Guys,

That's the longest thread I've ever read!!!

Just bought a 1994 80 avant last week. (220k miles) Was worried about the judder before I read this.

Thanks guys

I now know its not a major problem, just a "few" quid to fix. (or "a quick snip will do it" - now, where have I heard that before.....)

So, this i what I need to check/do -

1-No 3 injector replacement (I assume I'm better off replacing them all!! Correct?? )
2- "swarf" in injector pump - clean out.
3-Cut the dash wire (that's going to be fun - colour blind )

I have access to a 93 avant that I can use for parts. I assume I can straight swap the injector?

Great thread,
Thanks,
Arderra

[scotty33]

I don't know what others think, but the way I read it, the inj pump swarf seems to be the most common issue. Unplugging the speed sensor or pulling the fuse for the instruments has the same effect as cutting the blue/white wire. If the car is improved and you are happy with the throttle response you could get away with cutting the blue/white wire.
Doing this does not solve the problem, but it does mask the issue?
The full pump repair appears fairly straightforward, but probably not for the faint hearted?
The no.3 injector issue is another one that can cause running problems, but i think it will give a fault code? If you choose to change all injectors I would consider ones from the AFN 110 hp engine, you will get a bit more bang for your buck!