MK3 Golf 1.9 TDI Engine Judder

[chrisyboy]

Hi everyone I have just brought my Golf 1.9 TDI and so far really impressed! There is only really one problem worth mentioning!

When hard accelerating, the engine picks up revs / speed however stutters, almost like an on/off switch is constantly being pressed! Also when driving along between 60-70mph it also stutters, hunting symptons but not at any other speeds!

The idle is pefect so problems only most occur at certain revs which is from 2k to 3k

Has anyone got any ideas, i Notice there is a Tuning Box, could that cause any problems?

[popcornfox]

I have similar problems on mine but not under hard accelration. I dont think it can be the tuning box as i dont have one.

I thought it was the EGR valve so blanked it off. This didnt help with the judder.
I have also run 10K boost through too, runs better but still has judder.

Other new bits lately are new mass air flow meter so cant be that, pipercross air filter and decat with performance backbox. so again cant be any of these as the problem hasnt shifted!
Btw mines the AHU engine code

[Jimmy B]

Give it a service if it hasn’t had one yet, things like the diesel/fuel filter may need changing. Apart from that the AHU’s are really good check for things like vacuum hoses may be loose or perished causing air leaks?

[popcornfox]

Yeah it's not long had a decent service ie engine flush new filters all round new oil and many treatments of injector cleaner.going to try fully removing the egr valve soon and see how it goes!

[chrisyboy]

From what I can see the engine has been recently serviced and there is a new fuel filter! Also its not the AHU engine but the IZ engine, well thats what I have been told anyway! Will have another look but cannot visually see anything wrong! It seems to start just after 2000 rpm, any ideas?

[solomonp]

I have the same problem with a 1998 golf TDI ahu I have had since new. The slight judder when not under load at 1200 to 1500 rpm is getting annoying. It has an uneveness now when at tickover aswell, that it never had before. Has anyone tracked down this type of fault? After 2 weeks studying the foriums I have found others reporting it , but no one saying they have found a cure. I have checked the MAF and that is OK. My garage has checked for fault codes and there are none and could find no pipe leaks around the manifold areas. I have replaced fuel and air filters.
How can I check the fuel pump and the crank sensor. Surely the fuel pump must be OK as the engine still has plenty of umpph and the fault is present at tick over.

Hope some kind soul is reading this post!

[micheal balbrig]

Have a look at the audi 80 tdi juddering bucking jerking, it appears similar
The problem was with the electronic unit of fuel pump, engine in my case was 1z
The kangarooing would start at about 1500 revs, light or heavy foot. idle was also erratic.
These engines with high miles often benefit from cleaning the inlet manifold from carbon build up to help breathing.

[solomonp]

WOW. thanks Michael for your reply, what a reference you have given me with nearly 300 cintributions to that post ( audi 80 tdi juddering bucking jerking). I will get down to reading through it. With it being a thread for Audi 80, I could easily have never come across it without your help. Although old , my car has only done 80,000, so I dont want to say goodbye without a bit of a fight!

Peter

[solomonp]

Have a look at the audi 80 tdi juddering bucking jerking, it appears similar
The problem was with the electronic unit of fuel pump, engine in my case was 1z
The kangarooing would start at about 1500 revs, light or heavy foot. idle was also erratic.
These engines with high miles often benefit from cleaning the inlet manifold from carbon build up to help breathing.

micheal

I must thank you again for suggesting that link to 'Audi 80 tdi juddering bucking jerking '.

After reading all 30 pages, I was almost certain that the problem with my Mk 3 Golf AHU engine was the same. The work around of cutting the speed signal wire to pin 43 of the ECU seemed to be the way of proving it .
( I must point out here for anyone doing this mod. that before doing anything , be sure to disconnect the negative battery lead. When you reconnect, you may have to reset your alarm ...but that is another story. )
The wiring on the Golf is a bit different to the Audi, so for the benefit of anyone else doing this, I thought I would put down here what I did. I had a look at the ECU connector to see if I could get access to pin 43 but the harness is so massive and any mistakes here could have such serious consequences that I chickened out.
I needed to find the other end of this wire, which from the cicuit diagrams I had, was a junction block numered TV13. I found that this was one of a number of junction blocks that are mounted on a metal cross member just above the fuseboard / relay panel above the driver's foot well. The blocks are of different colours with matching colour plug connectors. TV13 is blue. In my car this had 3 wires connected to it. (The circuit diagrams I had indicated there should only be 2).



To gain access you need to remove the instrument cluster, not completely, just enough to unplug the connector from the back, and then position it to the left hand side, against the back of the lowered steering wheel. Also, I dropped the fuseboard/relay panel so I could meter connections to check which wires went where. If you google both of these disassemblings on Youtube you will find some very helpful descritions and videos on how to do this.



From the circuit diagrams, the speed signal (vss) leaves the instrument cluster on pin 7 of the connector. This wire on my car was white, as were many of the other wires. The diagram shows it goes to blue plug U2 pin2 on the relay panel. This was checked with a meter. Internal to the relay panel, this pin is connected to green plug W pin 1. This pin has a. blue/white wire which then goes to the connection block TV13. Metering it will determine which one of the 3, that connect to TV13, this one is. One of the other two blue/white wires must be the wire to pin 43 thatneeds to be cut. But which one? If I was more brave, I could ,of course, have unpugged the ECU and metered the connection from there but it looked old, fragile and a bit corroded. Best left untouched!
More research on the internet turned up the fact that a speed signal is sent to the radio plug ,as some radios turn the volume up as you go faster. I took the radio out. To remove mine, a Sony cassette , which had a detachable face plate, I found two short lengths of broken off junior hacksaw blades pushed into the slots were good to release the radio. There was a blue and white wire to the plug and this metered through to one of the connections to TV13. By elimination, the remaining connection had to be the one to pin 43.
TV13 is perfect for breaking the connection to pin 43, as if you want, you can just disconnect the plug from the block and leave it hanging. I preferred to make up a lead and bring this out to the dash and put a small switch there, so I could connect or disconnect pin 43 at will. So as to allow things easily to be returned to their original condition, I decided to get VW plugs and sockets that matched the TV13 connector ones ,so my extension lead to the switch could be easily removed if necessary.
THE RESULTS
As the uneven running at 1500 to 2000 rpm had been developing in the past months, an engine warning light (the flashing glow plug light) had appeared on some days. More recently it had been coming on more frequently. I started the car with switch 'on' and pin 43 connected. It ran OK. No flashing light but after a few minutes it started to flash. Running was uneven as usual.
I turned the ignition off, turned the switch to 'off', and restarted the engine. Again no engine warning light initially, but it came on after a few minutes. This time there was no uneven running. A real improvement. I did not notice any increased sharpness in the action of the accelerator that had been reported by some Audi owners. The tickover had been a bit irregular for some time with a tendancy for the speed to hunt slightly. This was still the same with pin 43 disconnected.
NEXT STEPS
I think I will get my garage to do a vag com to see if they can diagnose the flashing warning light with the pin 43 connected and disconnected. I am concerned that it might be just coincidental and unrelated to tyhe uneven running problem.
I believe that an engine warning light is now a reason to fail the UK MOT test, so that could be a problem for me.
As experts here have said that the real solution to this problem is in the electrical control circuit at the top of the injection pump, I intend to get in touch with a diesel servicing company to see if they do any repairs and what the cost might be.
I have not thrown the switch when the engine is running yet.....does any one know if this might have dire consequences?



Peter

[mr fixit]

Follow upto my last post

I have checked, using VCDS lite and a cheap lead, what the flashing warning light is for. It comes up as " 01268 - Quantity Adjuster (N146) 35-10 -- Intermittent". I am reassured that this is the same fault as this wire cutting work-around is addressing and nothing else is wrong with the engine. I can reset it with VCDS lite but it comes back after a few minutes running of the engine. Perhaps there is someone out there who can advise if the limits can be set wider to avoid this fault showing up. Operating the switch while running the engine has not resulted in any problems and does not affect the note of the engine at all. In both positions of the switch the uneven (hunting) tickover is present. This is annoying but liveable with.

A proper repair by repairing or replacing the injection pump is too expensive for me to consider.

Peter