Audi 80 tdi juddering bucking jerking

ok, i give up. after weeks of trying to figure it out. has anybody else got to the bottom of the audi 80 tdi (1z engine) problem where the vehicle judders/jerks/bucks at light load at anything between 1200-2000 rpm

after this it clears, also flooring it, it will pull through.

symptoms like this have been described by so many people, but no one knows the problem as of yet.

in a few cases, it has been said that the car also idles roughly, as is the case with my car.

PLEASE HELP if you know what it might be. i will not list everything that i have done, as the list is too extensive, instead i will read comments and let you know whether i have allready tried what you suggest.

i know there are more than five people knocking around the net with this problem, and some of the posts are a year old or more, and the problem is unresolved

the closest i have come to curing the problem is unlpluggin my vss (vehicle speed sensor). this seems to eliminate the problem. however i cannot run the vehicle like this all of the time as i have no speedo or odometer and it also disables certain engine management functions.

i look forwards to hearing your replies

I would guess you have checked most things but when my 80 was juddering a few years back it turned out to be gearbox to engine bolts, 3 missing and the rest loose. It was ok when I was accelerating hard but on idle and light load it was juddering quite badly.

hi baggabones. thanks very much for your reply, ill check it they are all tight

Hi avanttdi,
As midskev mentioned on the other thread, the juddering is frequently caused by the timing belt tension (or lack of). The tensioner works on an elipsed spindle, which I am guessing wears out, causing a loss of tension.
Mine starts to judder after a couple of weeks driving, and sure enough, every time I take the cover of the front, the tensioner has slipped a little.
Try tightening it using circlip pliers (so the crescent is verticle) and see if that works. If it does, and it starts to judder again after a while, a new tensioner is certainly needed.

Of course, as other people have seen, there are dozens of other things that can cause juddering on these wonderfull cars!

hi hope your all well,

im getting old going grey but the old bugger still judders new cambelt and new kit pullys tentioners ect its a far more driverble and economical it dosent smoke u can even redline it unless it overboosts doesnt do that unless u floor it, pulls far better on less right foot, will i die with this problem lolol will a lump of metal plastic and rubber be the end for me, even audi havent a clue,

and does anyone know where the vaccume pipe that goes into the ecu comes from i cant see it to trace it its the only one i havent changed, going take intercooler off next and clean that out, gearbox bolts fine but i did hear thar the oil can evaperate in there so getting it up on mates ramps to check it and put some addrtive in it, and if anyones got a vaccume turbo wastgate acctuator of a 1z 1.9 tdi plss its last gasp ideas now,
i got a new throtle potentiomiter to put on i had a look need some torx spanners and lose 4 stone to get at it but ill see if that does anythin,

keep working lads then when we get it sorted we can sell the remedy to audi lolololol

ohhh ps
aint it nice to see the sun yeahhhhhhhhhhhhh

Hi i have the same problem at about 2000 revs.

By chance I have found that by taking out the instrumant panel fuse (no. 12 I believe) the juddering completly DISSAPPEARS. The engine runs fine.
Obviously this isn't a very good solution with no speedo and other instrument panel gauges working , but it might help give an indication of the cause.

My guess is that the on board engine computer is getting bad rev or speed information, or is malfunctioning.

Has anyone got any ideas. Could replacing the engine ECU help ?

Disconenting the rev counter?
Does anyone know how you would do that ?

please help, I can't take these shakes much more

:aargh4:

Doh! sorry didn't realise you had already come across the disconecting the speedo effect.

I would suspect fueling as the cause of the problem, vag-com readings would be a great help.

First disconnect the maf and see if it runs any better.

If not, check the injected quantities & timing are in range with vag-com etc.

Are the fuel and engine temps in range?

If you have your radio code (if needed) disconnect the battery for 30mins, and see if there is any change.

If no change, try disconnecting the engine temp sensor and see if the problem occurs.

Has the fuel filter been changed recently, + are the injectors ok?

I would suspect a worn/loose valve or advance/cam/piston mechanism in the pump.

thanks for the reply

There are no Vag readings,
there was a bad MAf reading a year ago and i replaced that.

Have disconected the battery and maf, but it doesn't help

Where abouts is the engine temp sensor?

Should be located on the top coolant hose very close to the engine block.

You need to check the 'injected quantities' with vag-com.

Also accelerator pedal switch.

Could also be ECU electronic component problem though.

Here is some info relevant to your 1Z:

http://pics.tdiclub.com/data/529/135...echnik-eng.pdf

Thanks ini for that nice pdf.
Has anyone read the bit about engine shudder suppression and the
clutch pedal switch?

Lo there all1, new member here, i'd like dto say a quick hi to all fellow Audi 80 owners.

I've had the same juddering problem as others in this thread and have yet to find a proper 'cure'. I've even experienced the dead speedo sympton and found that a good thump on the dash cured that too!

I've checked out various possible causes including the engine mounts and gearbox and clutch, all to no avail.

Thnx for the pdf file, a most informative read though i'm struggling to actually get access to the accelerator pedal actuator, which i feel is the most likely cause of the said problem. I've noticed that my engine ticks over rough, seems to be 'hunting' for a rev setting.

Earlier i was disappointed by a quick trip to Audi dealership across the road from me, who 'hazarded a guess' at the fuel pump and gave me the address for their sub-contract deisel fitter. He turned out to be less than helpful, though he said he cleaned my injectors.

Has anyone yet solved this problem? or got any idea how to get to the accelerator pedal acctuator?

hi wellcome to the judder club !!!

if you remove the shelf under the drivers side and the grey plastic gaurd its tucked right up on the bulkhead u need a torx key to undo the studs not a big job just back breaking i got a new one to put on so thats a job for weekend need a torx set tho lol

good luck

Hello, fellow judderererrreerrrrsssss

I am a new member to this rather unique club, we should all meet up then judder up the road together !!!

Anyways, any new news, symptons, well the ususal

Judder at low rpms, when i first got the car, the speedo wouldn't work for a mile or 2 then would start.

Didn't do it though until i put a tank of fuel in though.

Initially thought it was engine / gearbox mountings.

You would have thought VAG would have a solution as the engine is used in VW too, or is it an AUdi only problem, which would sugguest some electrical malfunction purtaining to Audi's only ??

Need to fix this some how, ruining a perfectly good car

COME ON AUDI, GET YOUR FINGER AUS !!!!!

Quote:

---

Originally Posted by midskev

hi wellcome to the judder club !!!

if you remove the shelf under the drivers side and the grey plastic gaurd its tucked right up on the bulkhead u need a torx key to undo the studs not a big job just back breaking i got a new one to put on so thats a job for weekend need a torx set tho lol

good luck

---

Let me know how you get on, if that makes any difference??

:biglaugh:

i most cerainly will, i'm assuming that midskev hasn't had any joy though, sound slike he's already had a crack at it. Look slike it might be better to take the drivers seat out to do this job though!

Lo there Midskev, where did u get your actuator/ potentionmeter from and do they come to peices at all? I think giventhat the speedo seems to affect the juddering problem then there must be something wrong in the speed control closed loop circuit, and i'm wondering if it's just a worn or poor contact slider in the potentiometer.

Does the 'stumbling' or 'hesitation' from 1200-2000rpm go away when the engine is warm?

If it does, i would check that your 'at idle' fuel injection quantity is around 4.0-5.0mg/stroke.

Suspect fuel temp sender, or fuel pump advance mechanism.

If the problem goes away when you disconnect the speedo, the car is possibly running default values for some sensors.

the problem is there all the time m8, i mean, it never goes away or changes in intensity, it does it hot or cold. I can't say as i've noticed anyway of releiving it whilst driving, usually i drop a gear and accelerate beyond the trouble zone. and then all is ok. the car's top speed is unaffected and fuel consumption seems as normal. engine temp ok and no water loss. oh, and it ticks over rough, seems to be hunting for 900 rpm. any other clues? i'm veering away from fuel pump myself, that's a real expensive item to replace and i'm assured if it was the problem, there would be no if's or but's about it, the car wouldn't run.

Just out of interest, does the idle rpm alter if you suddenly load the electrical system? (turn on main beam, wipers etc)

You need to post some vagcom measurements, fuel & engine temp, timing, injected quantities etc, all the normal stuff.

I am convinced that the problems are fuel pump related, the fuel pump contains quite a few devices, and the actual bit that moves the fuel very rarely fails.

It may be worth visiting a Bosch service centre and having the various pump components checked, this can be very inexpensive.

Also, do you have any means of visually checking whether there is any air entering the fuel lines?

Have the injectors been cleaned recently?

hi guys, as the creator of this thread its good to see so many people trying to help, and also to know that other people are having the same problem tracing the problem.

anyway heres an update

i have been driving my car around for a while now with the speedo unplugged to stop it juddering and as mentioned before this seems to make it driveable, although sometimes (it may be in my imagination) i think i car feel the car juddering very very slightly. however if i plug the vss back in, the problem is exaggerated tenfold.

the vss signal is used for an engine management subfunction known as active cirge damping. this function uses several other sensors and is designed to smooth driver input and reduce sudden jolts of torque in the drivetrain.

now i have been giving this some thought, and i have decided that the rough idling is indeed related to the juddering problem. The engine management system uses the crank sensor to maintain idle between set parameters......the link here is that this same sensor is also factored into active surge damping.

My thoughts now, and my plan of action is to try unplugging the crank sensor as this engine management system does not actually need it to run. I know it will go into a mild stage of limp home mode as it will use the needle lift sensor as a substitute signal for engine rpm.

ill let you all know how i get on .
also i may try scoping various signals at the ecu to check them for noise.

hi
im with you on that ava its got to be electrical funny but yesterday it was a wet day very humid the car ran far better than normal even started better and its always been a great starter, let us know if it works i still got to get a torx set to do the throttol petentiomiter im like you determined to sort it out lolol but slowly going grey lolol

keep up the good work

lo there ini, thnx for the interest btw, sorry buti can't post vagcom stuff, not sure what that means so have no idea where to get the readings you require. Yes, fuel injectors where cleaned recently, by a deisel specialist used by Audi Lincoln. Not convinced of his efficacy since he broke my accelerator pedal and cable-tied it back together and blocked the EGR valve vac feed with a ball bearing, for what purpose the almighty knows.

Needless to say i'm now going to try and fix this myself, the clutch is a new one and there's no loose bolts or mounts.

NOTE: don't bother with the throttle potentiometer, i removed mine and disconnected it, there's a six pin plug near to it that feeds it. the idle speed increases to factory default emergency throttle, but the hunting still continued! it ain't the throttle gadget!

These 'case relief valve' threads may be useful:

http://forums.tdiclub.com/showthread.php?t=107803

http://forums.tdiclub.com/showthread.php?t=179625

thnx again Ini, nice post there, worrying and interesting at the same time. I dunno if i can risk trying to remove that device, i don't know if i can get the pump off on my own never mind try to take it apart. That may be a bit beyond me. And it doesn't seem to stay fixed for very long either! hmmmm, may be as well to get a new pump, are they a direct swap or need setting up?

Helllo juddererrreerrs,

My 1993 1.9tdi, hasn't got a rough idle, judders at low rpms and temp cuts out for a split sec, all randomly, whether hot or cold, admitedly, more so when warm. even so, still very random.

First thought was water in the fuel, then thought air in the fuel, as i seem to have air bubbles in the fuel line going to the pump.

Pos throttle sensor (bloody electrics, on an oil burner!!) or timing belt.

I would have thought though, if the timing belt tension is slack, and the teeth are jumping, that this would kill the engine ??

As my idle is fine, and most of the time the car runs fine, no leaks or odd noises, (apart from the driver cursing audi when it "cuts out") i wouldn't have thought timing ??

Driving me round the bloody bend !!:aargh4:

Lo ther Hawkeye, i don't think it's yer timing belt m8, if it had jumped over a tooth or two, then your pistons could strike the valves, and yes, that would kill yer engine. Not sure as you've got exactly the same symptoms as myself, since it ticks-over ok, but, i had Audi replace my timing belt and tensioner, it made no difference whatsoever. I can't suggest much at the moment, but it's not the throttle potentiometer (positioner), I'm pretty certain of that.

I think there was a post about air bubbles in fuel lines, but i can't remember what was said, something about a fuel filter. I've replaced mine several times and it never helps.

Thanks Obsidian,

This really is ridiculous, you would have thought Audi would come up with an answer here!.

Well, this is what happens when you put bloody electrcal boxs on good old oil burners !!

Keep up the good work everyone, glad i found this forum!!

:biglaugh:

This problem has had me stumped for months, but the VSS (Speed sensor) leads have really helped.

I have had shudder at idle but this can be tweaked with VAG-COM TDi timing checker and/or physical pump timing.

The main problem has been the quite bad jerk/shudder at low loads which will only dissappear when breaking the drive (clutch) or powering through. I've tried everything to stop this, engine mounts, MAF, N75 Valve, Cleaning Inlet Manifold, blanked off EGR, altered timing (physical and software) with no effect on this problem what so ever!

I finally got round to removing the dash fuse, then bingo all fine! Apart from obviously no dash. If you remove pin 43 from the ECM you get the same result, except you have the CEL flashing, I assume because loss of speed signal, but the speedo works ok. Pin 43 goes to pin 18 (on the blue dash connector behind dash), I assume the speed sensor feeds the dash which conditions the signal for pin 43 of the ECM.

My next step is to scope the signal, I have two wires hanging down behind the glove box at the moment so I can dis/re connect the wires when I need to, and also connect a scope.

Now, what does the dash do with the speed signal, I don't know yet, but I wonder if its a problem with the dash or whether we have some control loop problem as the cars are getting older. I've read that the ECM monitors vehicle speed to determine acceleration or deceleration.

It drives beautifully with pin 43 disconnected and you have all the dash functions, even the speedo working, I've removed the CEL bulb, while I'm investigating, but I'm determined to find the problem.

Anybody else have any more info??

Has everyone already tried replacing the engine bay/ECU power 'relay 109' to try and cure the problem?

The 'old' version is a known bad component on early TDI's.

If the relay is physically damaged/weak, the low revs vibration could possibly cause a regular intermittent sensor & ECU failure, which vanishes at smoother/higher rpm?

Just an idea, but it is a cheap component to replace (with the new stronger type)

cheers guys! hey Allan! where is this ECM thing and how do i get to it, your fix sounds liek one i'd liek to try myself, i do alot of miles daily, i can't tell you how it drives me nutty this shudder. I've not been able to locate a wiring diagram for my TDI, no manuals for them anywhere, so i've no idea where or what relay 109 is ini, but that really does sound worth a look at, any1 got a wiring diagram, i'm an electrician, i understand these things!

hey alan! let me know how you get on with scoping the signal, i was going to do this but never got round to it.

i am 90% sure that the clocks convert the signal from the analogue sine wave produced by the VSS into a digital (square wave) format that the ecu can understand.

please could you draw me a little picture or describe where pin 49 is on the ecu plug? i have been driving about with the speed sensor unplugged for ages, but i have to do a 500 mile trip soon, and so i desperately need the speedo working.

i can live with the rough idle, and i can take the flashing bulb out for the time being. btw what is CEL i have never come across this abbreviation.

please keep us all posted on your progress. dont find the fix, and then forget about us all!

many thanks

update as promised. today i tried unplugging my crank sensor ( for reasons/suspicions explained previously)

i would like everyone to know that it made no difference, so from this i have concluded that we are not dealing with an implausable or noisy crank signal.

the engine ran exactly the same using the needle lift sensor as a substitute function.

one more thing eliminated.....

Quote:

---

Originally Posted by allan_audi

This problem has had me stumped for months, but the VSS (Speed sensor) leads have really helped.

I have had shudder at idle but this can be tweaked with VAG-COM TDi timing checker and/or physical pump timing.

The main problem has been the quite bad jerk/shudder at low loads which will only dissappear when breaking the drive (clutch) or powering through. I've tried everything to stop this, engine mounts, MAF, N75 Valve, Cleaning Inlet Manifold, blanked off EGR, altered timing (physical and software) with no effect on this problem what so ever!

I finally got round to removing the dash fuse, then bingo all fine! Apart from obviously no dash. If you remove pin 43 from the ECM you get the same result, except you have the CEL flashing, I assume because loss of speed signal, but the speedo works ok. Pin 43 goes to pin 18 (on the blue dash connector behind dash), I assume the speed sensor feeds the dash which conditions the signal for pin 43 of the ECM.

My next step is to scope the signal, I have two wires hanging down behind the glove box at the moment so I can dis/re connect the wires when I need to, and also connect a scope.

Now, what does the dash do with the speed signal, I don't know yet, but I wonder if its a problem with the dash or whether we have some control loop problem as the cars are getting older. I've read that the ECM monitors vehicle speed to determine acceleration or deceleration.

It drives beautifully with pin 43 disconnected and you have all the dash functions, even the speedo working, I've removed the CEL bulb, while I'm investigating, but I'm determined to find the problem.

Anybody else have any more info??

---

Hey Allan, I joined the forum just now to reply to your post.
I have a similar problem, juddery/lumpy tickover (but sometimes fine) then the judder sometimes while accelerating and sometimes while cruising. Strangely it can run fine occasionally!
Also yesterday for the first time there was a lack of power (just once) until the revs were up a bit then the power kicked in.
I'm wondering whether to try your pin 43 trick, could you please provide some 'instructions for dummies'? And which bulb is the CEL one?
Thanks for sharing the results of your determined efforts to rectify a problem that distracts from an otherwise superb automobile!!

I almost 'upgraded' to a 1997 tdi Passat estate but after reading about all the electrical faults caused by rainwater in the ecu, and what with catalysers and so on I thought I'd stick with the trusty Audi! Anglesey and back (430 miles) on 38 litres can't be bad for a £900 motor!!

CHeers, Steve

VSS Vehicle Speed Sensor - Jerking/Juddering

Great to see all the interest! Bare in mind my car is 80 Avant 1994 1Z TDi, not sure if it applies to all, so please check first.

You can either remove pin 43 (White/Blue wire) on the ECM (which is located behind the glovebox, behind the heater fan). I found the pic/pinouts here;

http://www.hasenwerk.ca/tech/wiring/earlypassat1z.pdf

But it would be easier to cut the wire from the dash, I found that it goes to pin 18 (White/Blue) on the blue connector at the rear of the dash. You will find the markings for pin numbers on the socket of the dash, just count along to 18, then check the colour, cut the wire (insulate, just in case). To remove the dash remove the cowl (two screws underneath), then the two screws for the dash. You don't need to remove the steering wheel (disconnect battery if your unlucky enough to have airbag).

The CEL bulb is the one for the glowplugs, the orange lamp bottom left (then up one, I think!) to check just turn on ignition look for glowplug lamp, remove that one (its a bulb with blue holder).

I'm gonna try get round to scoping the signal! I did think that it might be converted to square wave here, so there is slight chance of fault in the dash VSS signal. I'm more wondering whether this is a closed loop fault, ie play in gearbox, not sure what the speed sensor picks up off, crown gear, dont know?? Maybe theres play in the gear that feeds the VSS. I know the gearbox on mine is fine but there's a fair amount of backlash in the drive train.

Whilst I'm here, there are other faults that people are discussing on this thread, I don't think they're connected to this cyclic jerking/juddering problem.

Loss of power seems to be a problem with EGR, MAF or boost. For instance one of the boost pipes had come loose on mine, I'd already blanked the EGR valve off, I tested the MAF using VAGCOM and seemed fine, then noticed a boost pipe was loose. I have heard of boost pipes splitting. I guess the best way would be to connect a boost gauge.

Incidentally I fitted pair of SJK Digital tuning chips, the difference is awesome, around 115BHP I think, the torque increase is excellent and doesn't seem to have affected economy much. Well worth the 60 odd quid, just need to remove the ECM and dismantle to fit. Its funny watchin some of the other cars try and get past up the hills!!

Anyhow, going on again, got so much info on this car, I'd almost given up with the VSS problem, but the cars so good to drive!! Plenty of life in her yet!!

Keep up with the info everyone!!

PS.

CEL - Check Engine Lamp, flashing (during engine running) indicates engine system fault, or at keyon indicates activation of glow plugs (plus lamp check, ie. CEL lamp bulb not blown).

I'm also not sure about 109 relay (this maybe a VW thing, I don't know if its same for Audi 80), this is the relay that powers up the ECM, I haven't changed it yet, but its possible this could cause intermittant problems, ie engine cutting out, but I think this would be at all operating conditions. Suggest anyone wth misfire etc tries this one out, let us all know!

I don't think its connected to the VSS problem.

PPS.

I've had not luck with help from Audi so far, they're not interested, its so frustrating not to have a wiring diagram for this car!!

QUOTE>>

lo there ini, thnx for the interest btw, sorry buti can't post vagcom stuff, not sure what that means so have no idea where to get the readings you require. Yes, fuel injectors where cleaned recently, by a deisel specialist used by Audi Lincoln. Not convinced of his efficacy since he broke my accelerator pedal and cable-tied it back together and blocked the EGR valve vac feed with a ball bearing, for what purpose the almighty knows.

Needless to say i'm now going to try and fix this myself, the clutch is a new one and there's no loose bolts or mounts.

NOTE: don't bother with the throttle potentiometer, i removed mine and disconnected it, there's a six pin plug near to it that feeds it. the idle speed increases to factory default emergency throttle, but the hunting still continued! it ain't the throttle gadget!
<<


Funny, the ball bearing is to stop the EGR valve opening (assuming its already closed when you stuff the ball bearing into the pipe), bit crude, especially seince they mostly fail stuck open (physically). Best idea is to make a blanking plate for the EGR valve itself out of some plate steel, so even if the valve opens exhaust gases cannot reach the inlet. EGR valve is known to cause problems, inlet clogging with black oily crud, plus sticking open etc, loss of power/boost. Its not really needed, its only there to reduce NOX emissions.

I'm fairly certain that the clutch has nothing to do with the jerking juddering.

I was also convinced that the throttle pot plays no part in the jerking, since it would cause problems on and off load. ie. you would be able to get the car to jerk in neutral by adjusting the throttle.

that's interesting you should pick up on that allan, i've looked at the egr valve before, took it off but i can't seem to get any movement in it, i just assumed it need quite some force, but maybe not! Worthy of another look. I also, whilst at that valave, took my pipework off to look further and found there was considerable crude in the inlet manifold. I'm assuming that's what it is anyway, it's a silvery box along side the engine, seems to be quite full of oily crude. is this what you mean by faulty egr symptons?

thnx for the pdf, interesting read that.

still strugglingto find this 109 relay!

Quote:

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Originally Posted by Obsidian

that's interesting you should pick up on that allan, i've looked at the egr valve before, took it off but i can't seem to get any movement in it, i just assumed it need quite some force, but maybe not! Worthy of another look. I also, whilst at that valave, took my pipework off to look further and found there was considerable crude in the inlet manifold. I'm assuming that's what it is anyway, it's a silvery box along side the engine, seems to be quite full of oily crude. is this what you mean by faulty egr symptons?

thnx for the pdf, interesting read that.

still strugglingto find this 109 relay!

---

Just to point out EGR fault doesn't cause the VSS problem we're discussing.

Look at the TIDCLUB page for info on EGR, I took my manifold off to clean a few months ago, absolutely caked in crud and can affect performance if severe. The EGR recirculates exhaust gases which mix with the oil from the breather and turbo to coat the inlet manifold. So I cleaned the manifold and blanked the EGR, should remain clean now.

http://tdiclub.com/TDIFAQ/TDiFAQ-7.html#g


There's mention of the 109 relay on the TDICLUB too, I'm guessing its in relay box under bonnet or could be one of the relays under drivers side dash. Anybody know???

This is for an A4, but the relay is most likely in the same location.

http://forums.tdiclub.com/showthread.php?p=300195