Golf TDI injection timing - starting problem

[Robble]

Hi

I've been having a problem with starting my Golf TDI (1Z engine) for the last few months. I checked and replaced glowplugs and wiring but that was not the problem. Someone suggested I should check the injection timing as it may be too far retarded. I bought myself the VAG-COM software and lead, plugged it all in and discovered the timing was indeed too retarded.
A couple of weeks ago I advanced the timing and set it within the specified limits and since then it has been starting faultlessly. Great!

The car had been difficult to get warmed up for sometime and last week a local garage changed the thermostat for me. Car now warms up much quicker. Car was still starting OK.

Car had been difficult to warm up as I mentioned previously. On tuesday I got the garage to replace the thermostat and it has been much better the last few days and still been easy to start.

Yesterday morning I got in the car, its not particularly cold and its difficult to start again! Back to where it was before! When I got to where I was going, the engine was nice and warm, I checked on the VAG-COM and the timing it says on the graph is too advanced (above the top line). So I thought maybe I'd advanced it too far and needed to retard it a bit. Not sure why it would have changed?

Left the car round a friends house for 6 hours or so. Started it up and it started OK. Turned it off straight away, went indoors for a coffee, came out half an hour later and tried to start it and it was rough again!

Drove home, plugged in VAG-COM, plotted out the TDI-timing graph again and its back to saying "Timing to retarded to be plotted!"
I thought maybe the pump was loose, but I opened the bonnet and from the marks I made then it looks to be in the same place.

I read out the fault codes and it found two (below). The top one was on there a couple of weeks ago, but I ignored it. Not sure what either of them mean.

Control Module Part Number: 028 906 021 AF
Component and/or Version: 1,9l R4 EDC SG D80
Software Coding: 00000
Work Shop Code: WSC 00000

2 Faults Found:
01117 - Generator Terminal DF Load Signal
27-10 - Implausible Signal - Intermittent
00550 - Start of Injection Regulation
17-10 - Control Difference - Intermittent

Any ideas anyone?
Thanks
Rob

[kenney]

Think you have a problem with your pump

[Robble]

I hope not!

The timing belt has been on there for over 40,000 miles (60,000 replacement interval). I am wondering if the injector pump has skipped a tooth on the belt, maybe because of a worn or loose belt? I have taken the top cover off the belt, but I'm not sure how tight it is meant to be.

Thanks
Rob

[kenney]

I dot think so,if the belt is too slack there is a bigger chance of it jumping a tooth on the camshaft,it having more resitance than the pump.and when it does this its goodbye.If you have checked the basic timing with the same fuel temperature,each time, and you get differant readings,then it is the regulating valve in your pump

[Robble]

OK thanks, is the timing mechanism repairable in the pump or is it time for a new pump?

[kenney]

It is repairable,but we are talking about spesial workshops for Bosch,if you tell them the fault readout they will be able to quote you a price

[mad-for-tar]

Most Bosch rotary injection pumps nowadays dont have any keyway in them when the pump drivegear is fitted to them. There is a remote chance that it might have spun slightly on the shaft, thus your reason for altering the timing via VAG-COM to get it back right. Doing that has brought it somewhere in line to what it should be but temperature differences will cause exactly the symptoms you have now.

Timing a Bosch VE pump is relatively easy when you have the equipment. It just needs a special adapter and a dial test indicator which screws in place of the blanking cap in the middle of the rear of the pump where the injector pipes come out. I'm not sure whether there is some sort of electronic device on the back of these pumps or not for this particular model. 9 times out of 10, for a turbocharged diesel engine running a Bosch VE pump, you should have 1mm lift on the internal plunger, shown by 1 revolution of the dial gauge. I.E. engine is rotated in reverse until dial needle stops falling, when engine is turned in normal direction of rotation, you should see the needle count up to 1mm by the time the mark on the crank pulley reaches its timing mark, which I think is 0 degrees on this engine.

Probably not of much use to you but thought I'd explain the general principle of timing a Bosch VE fuel injection pump. Hopefully it might hep you a bit should you have to have it checked by a garage or a Bosch agent.

[Robble]

Thanks for the explanation mad-for-tar.

If this is what has happened to the pump, then is it repairable?
If it has spun on the shaft then I guess it could do it again even if were all reset correctly now?

Afer starting again earlier with difficulty, i now have another fault code:

01237 - Fuel Shut-Off Valve (N109)
31-10 - Open or Short to Ground - Intermittent

Rob

[kenney]

Sorry to disagree with you Mad for tar but i still think it is an electrical fault.the fault code read out with the new code robbie has 01237 and the 17-10 these are 2 electical controlled valves at the back of the pump.17-10 is the commencement of injection valve and 01237 is fuel shut off valve.They have 1 thing in common there is a 2 pin connector at thr rear of the pump have a look at it for bad connections, oherwise (N108) commencement of injection valve is defektive

[kenney]

SORRY forget 17-10 it is of course 00550