Engine cuts out on Mk 3 Golf TDI

[Paul C]

I have a Mk3 Golf 1.9 TDI. The engine cuts out, usually during the first few minutes before reaching full operating temperature, and will not restart for 30 seconds. When the engine cuts the spedo and rev counters go to zero. If I am still rolling after 30 seconds the spedo will restart and show what speed I am doing, if the engine is very cold the glow plug lamp will come on after the 30 seconds. Once past this the engine will always restart on the key.

Has anyone come accross this problem or have any suggestions where to start?

Thanks
Paul C

[CossieMoJo]

I had this problem with my Mk 4 TDI. It cut out 5 times in one day on the motorway - everything just cut out - power assistance for steering and brakes all lost. Turned out to be something called the step up relay - a little black plastic cube into which cables fitted into. My independent garage fixed a new one that same morning for £40 all in. AA had no idea what it was.

[Alun]

Sounds like an electrical fault. Maybe theres a loose wire on a relay somewhere? Or maybe some kind of vacum pump somewhere within the engine? You best bet is to take it to a trusted garage and get a full engine diagnostics done. Pricey but it will solve the problem. I got quoted a full service and a full engine diagnostics for £80 (from a trusted friend, usually £120)

[nick1.9GTTDi]

Do you know if there is another name for a step up relay(or where it is),my local vw garage have never heard of one and it sounds like what i need.Thanks,Nick.

[j_coupland]

Could it be a stepper motor for some kind of idle speed control valve? I had a cold starting problem ages ago with my Cavalier SRI 16 valve and turned out there was an idle speed control valve at the top of the engine throttle body that controlled the amount of air going in to keep the engine ticking over. All I needed was a spray of WD40, a spray of carb cleaner and a new gasket to reseal the valve and it was fine. It saved me £120 for a new valve! There might be a similar system for your engine, worth checking out.

[mojogoes]

Hi guy's,

The fault is a relay i believe its called the 109 relay , if this relay goes its game over i think its located under the right hand side of the dash board..............anyway talking about dashbords i could fit you a new relay as i put one of my carbon dashboards you've bought from me in ........no!!! oh well.

[Paul C]

Yep. Replaced the relay 109 (slot 3 from the left on the upper row of relays) apparently it switches the supply for the ECU so when it fails the ECU does not register any new fault codes, just thinks the ignitions been switched off. Cost from VW £12.00 and hasn't failed since.

The ones to look out for are the old type black relays, prone to this problem. New type grey ones don't suffer the problem.

Thanks for everyones help and suggestions, all worth trying.

Paul