MK3 1994 Golf Cabriolet, 1.8L ABS engine code, intermittent cutting out.

[Drenon]

Hello there all you wonderful people hoping some may be able to help shed a light on this issue I have been having

So a bit of history first, the car I have only just got but it has been in the family for at least 15 years now, was my mothers then unfortunately it was sat rotting away on her drive for the best part of 5 years. Fast forward to now and she had passed her MOT with only one advisory and was running a dream until about a week ago.

It started while on the motorway, the engine just lost all power, no warning lights on the dash, RPM still up and speedo still working until I dipped the clutch and it was like she had just been turned off. Got onto the hard shoulder, a couple of cranks later and she fired straight back up once again but only now for her to be doing to regular. I have not noticed any pattern to it either. High revs, low revs, fast, slow, aggressive driving, passive driving, sometimes it does it just from trying to set off from a junction yet never seems to be when it's sat idling.

Short journeys tend to be fine, the longer ones once she has warmed up it gets more and more regular and have been trying to hunt this problem down for a little while now. A lot of forum searching seems to have a lot of people pointing to the crank speed sensor yet this engine doesn't have one so it can't be that.

Up to yet I have tried a few things,
-New coil pack
-New HT leads
-New Spark Plugs
-New Temp Sensor
-Checked fuel pump and its at least running and priming.
-Tried jumping the fuel pump relay to see if that was the issue but no

I'm running out of ideas now and in the process of trying to source a code reader to do some better diagnostics but here is hoping that some of you may have a little bit of a idea I could head down to see if I can solve this as I do a lot of motorway miles for work and it only seems to be getting worse.

[Crasher]

This car has no engine Malfunction Indicator Light (MIL) so take no comfort in non showing. It sort of has a crank speed sender but is actually the cam position sender G40 which does the job and this is the hall sender in the distributor.

[Drenon]

I have read about that in a few places now but not something I just want to buy randomly to attempt to fix the issue as they seam to be a little on the pricey side compared to what I have already just thrown at her.

Is there any way to test it at all? All I really have is a multimeter, I'm looking at buying a KKL reader with a older distribution of VCDS as I understand that even though it has a OBDII style plug it still runs on the old ODB1 style system?

[Crasher]

It is on the edge of having the VAG specific so called 2x2 plugs behind the switch blanks or the OBDII STYLE 16 pin plug behind the slide to the right cover above the ashtray, but no the ECU does not have OBDII protocol. VCDS Lite should cover most of what you need BUT with this ECU if the engine is not running the fault code for no hall sender (G40) signal will always be present. Apart from checking the wiring continuity of pin 2 back to the ECU J257 and the power across pins 1 and 3 of the G40 plug there is no test you can do with a multimeter, you would need an oscilloscope to check for a pulse. N157 is the amp and N152 the coil.

[Drenon]

So I have gone ahead and checked things like you suggested today.

Continuity between the G40 plug and the ECU is good, maximum resistance of 1ohm even when moving and wriggling wires around.

Voltage across pins 1 and 3 does have a slight voltage drop, reading out at 11.45V while the battery was at 12.06V, from having a look around I believe that is pretty neglible as that should work right down to 4v?

This is slowly starting to turn into a possible garage job for me as things keep going, I am aware if I was to replace the Hall sensor I would have to remove the distributor itself and I don't have the means to re-time the engine just at this moment, I'm having enough fun trying to source a KKL VAG cable for a reasonable price as it is at the moment!! XD

its a little dark at the moment but I do think tomorrow for piece of mind I will check for continuity from the ECU to the coil itself, I can't see that being the issue personally but always worth a check really with it's age and being sat for so long, if it's anything like our old Talbot motorhome the electrical gremlins are always a bugger to chase down.

[Crasher]

Yes changing the dizzy requires a timing light AND VCDS to put it in setting mode. Which make of dizzy is it, Bosch or Valeo?

[Drenon]

I will admit I'm not 100% sure but from looking up the part number I belive it may be a Bosch?

Part no: 1 230 329 033

Printed just next to the 3 pin plug for the dizzy hall sensor

[Crasher]

It should be VW number 050 905 205 AH and a Bosch exchange 0 986 237 636 the new part (no longer available) was Bosch number 0 237 520 036 but the number 1 230 329 033 is a cable connector. You can also buy the Hall sender as a spare part such as the Vemo
V10-72-1112

[Drenon]

So!!! To slightly resurrect this I have finally sussed out what was going on. After tackling and replacing practically all of the ignition system the car finally gave up and wouldn't start again, leave me stranded.

Found there was no fuel at all getting to the injector, turned out my problem all along was a fuel pump!!

It was odd, no weird sounds from the pump, the relay wasn't getting hot, nor was it pulling high amps it just wasn't pumping enough, there was little more than a dribble coming out when I unhooked the fuel line from the tank and tried to fire it. Wonder it it was potentially just failing internally as I do know it was original to the car.

Bought a pump, 1.2bar and she has never cut out again even after a good couple hundred miles of driving other than the odd stutter as I bought the wrong one, get a 3bar pump in and she should be golden!!