MK3 Golf 1.9 TDI Engine Judder

[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

[micheal balbrig]

As far as I know the quantity adjuster is part of the electronic unit on injection pump.
There is slight adjustment on the lid,but not recommended as it can have consequences.
Spend a little time talking to diesel specialists who may be able to help or they maybe able to fit a good used unit or pump.

On a second thought, it may be a good idea to inspect the circuit including condition of pins from the ecu to the fuel pump,there probably is a multi plug in engine bay there is also
a connector near pump to inspect,I am not sure or forget what the cables supply,one is fuel stop solenoid, this connection on some cars con get contaminated with oil.
Other members may be able to identify quantity adjuster cables/pins etc.