Audi 80 tdi juddering bucking jerking

The number of subjects covered in this thread is inevitable when the problem of juddering is so elusive! Virtually every bit of work, no matter how large or small *temporarily relieves* the juddering, yet without fail it always returns. The amount of detail everyone here has been over is astounding, and frustrating that no definitive results have been returned. I don't think my hoses have ever been replaced in the 252k miles (wen past quarter of a million a couple of weeks back, yay!) yet the problem is still there, although the intercooler cleaning is on my list of things to do. I can't really complain though, considering I bought this car for £200, + £200 parts to get it to good condition.
ps. check your fuel line near the tank for corrosion - very common fault and lets copious amounts of air into the line.

If the damper springs on the clutch plate have broken up and completely gone the slack in the drive line might mess with the speed sensor and give the jerking.
This would make sense as when power is full on up a slight incline is there no jerking?

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Originally Posted by TDi-iac

The number of subjects covered in this thread is inevitable when the problem of juddering is so elusive! Virtually every bit of work, no matter how large or small *temporarily relieves* the juddering, yet without fail it always returns. The amount of detail everyone here has been over is astounding, and frustrating that no definitive results have been returned. I don't think my hoses have ever been replaced in the 252k miles (wen past quarter of a million a couple of weeks back, yay!) yet the problem is still there, although the intercooler cleaning is on my list of things to do. I can't really complain though, considering I bought this car for £200, + £200 parts to get it to good condition.
ps. check your fuel line near the tank for corrosion - very common fault and lets copious amounts of air into the line.

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Without a doubt the problem with judder/jerking is to do with VSS, with the VSS mod I don't get any judder/jerking anymore. Its the occasional misfire that I now get which I'm trying to rectify along with the reason for the VSS signal elliminating the jerking. I'm still trying to get time to put a scope on the VSS signal.

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Originally Posted by stevegrass777

If the damper springs on the clutch plate have broken up and completely gone the slack in the drive line might mess with the speed sensor and give the jerking.
This would make sense as when power is full on up a slight incline is there no jerking?

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Its funny you mention this, I had considered this but changing the clutch is a fairly big job, has anyone changed clutch????. I had noticed before doing the VSS mod that when the caravan was hitched up the problem dissappeared and I mean completely. I'm convinced its something to do with play/backlash in the drivetrain (as you say possibly including the clutch). Interestingly it seems (I'm not 100% sure) the speed sensor is located on the output shaft on the drivers side of the gearbox. I can't help thinking that the sensor should be on the crown wheel of the diff, where most sensors are located. I really need to see the signal on a scope to see whats happening when the jerking occurs.

way ahead of yer there m8, already decided to do the air blowing thing, though i reckon i'll just use a needle adapter and bicycle pump from the ecu end, if i can figure out exactly where it is.

i know what yer mean about the variety of things discussed, we're all obviously enthusiasts for our cars and seemingly do alot of our own maintenance and repairs. It would be nice if we'd split this up on other threads, butit's too late now, lol.

Anyway, i took my drivers side caliper off and pumped the piston almost fully out, cleaned the exposed surface on the piston and greased and oiled the cyclinder, and workrd it in and out. It does seem a bit freer when i operate it manually, but it hasn't had any affect on the judder, maybe if i do both calipers it might.

Getting back to the juddering ........

I previously said that i had air bubbles in my fuel line, going from filter to pump, was wondering if they were causing the "cutting out" ?

Can't seem to get rid of them, so was wondering if i put an in-line filter in between filter and pump, whether this would stop them reaching the pump and poss. causing the cutting out ??

Any input ??

lo there all, look slike things have dried up on here now, maybe you've all given up or actually found the cure!?

Anyway, just to save someone sometime and expense, i've actually replaced both clutch and gearbox, it didn't do a thing for my car, and was very expensive. The cars' still bouncing along merrrily, though it runs a shade smooother more often now than previously, i think the problems an accumulation of issuses so i'm gonna keep trying..

good luck all, ttfn

no not given up yet

sorry to hear u spent lots of cash and still not sorted it, im convinced its electrical prob car runs far better in damp conditions so im not giving up, the cars great apart from this prob.

keep up the good work chaps

hi guys, i havent given up just been on holiday. did 1000 mile in the old bugger and she still pulls like a train.

back to the juddering/vss thing. im wondering if excess play/oscillation in the drivetrain could be enough to cause the ecu to do its nut trying to compensate with the ASD function.

reason i wondered this is because im now trying to think iutside the box, and i have severely knackered bottom arm bushes on my motor because i havent got round to changing them yet. hence the arms move back and forwards, which means so does the hub, the driveshaft goes into the hub, and on the other end of the driveshaft is the reluctor ring that the vss is picked up from.

just a thought

anyone else with knackered bushes?

i got top mount bushes that r really bad spose its all conected thro front suspention