Mk4 Golf 1.8t intermittent fault

[maxmc2]

Hi guys.

Purchased a little run around the other day and within a couple of hours the car broke down.

Was running fine then was pulling off a slip road and the car just died and lost power.

It start but would idle really erratically and i couldn't rev it past 1-2k rpm, if i kept pumping the throttle sometimes i could rev it up to about 4-5k but then it would just die.

Returned to it a day after still the same issue, went there the next day and car just started and drove fine, weird.

Got it home then took it around locally and all was fine until i reached 3-4k rpm again, now im in the same position again.

Any ideas, its not throwing up any codes this time so a bit stuck as to where to look first.

TIA

[Teh3692]

When I had mine the throttle body gunked up; symptoms sound similar. Took it off and cleaned it with carburettor cleaner and the issue never returned.

[catso]

My Son's MK6 1.4tsi had a similar problem, just died and wouldn't start. When I went to it an hour or so later it was fine and was OK for a week or more until it did the same again.

It did show low fuel pressure fault code though and it turned out to be a faulty fuel pump controller - sits on top of the tank under the rear seat and controls the speed of the in-tank pump which in turn supplies the high-pressure pump on the engine.



IIRC around £15 for a new one and a direct plug in.

[Tony1963]

I’d be looking at replacing the fuel filter first. It’s a favourite on these cars to forget about.
Then maybe the MAF sensor, another favourite, just gets dirty and tired, gives the wrong readings to the ECU.

[bangerhoarder]

Coil packs and plugs are service items on these engines. Always go for genuine!

[Belle427]

Could literally be anything so as suggested I’d change the fuel filter and give it a good service first.

[maxmc2]

Thanks for the reply guys.

The car had been sitting for a while so fuel issue isn't a bad shout, does any know how to check fuel pressure on vag com?

Also i'm getting a code re: O2 sensor but that could just be a secondary symptom, i'll also check and clean the throttle body and go from there.

[catso]

maxmc2 said:

The car had been sitting for a while so fuel issue isn't a bad shout, does any know how to check fuel pressure on vag com?

On the Mk 6 Golf, only the pressure at high pressure pump (mounted on rocker cover) can be measured from VCDS. That from the 'lift' pump requires a manual gauge to be attached and the pressure is regulated by the filter which has an over-pressure return line to the tank, I think older models would also need a gauge attaching?

As it happens, I changed the filter first as it may have been blocked or faulty but it was fine (I cut it apart to check for blockage) but the (lift) fuel pump controller is a known weak point - check how hot it runs, it should be mildly warm but can often get hot which is a sign of failure. Also, I noticed that I could hear the pump cycle from the driver's seat when ignition switched on with the new controller whereas before I could barely hear it even with the seat lifted with the old, failing unit.

Of course the above applies to the MK6 which is a direct-injection engine and so has the two pump setup: one to supply volume (but low pressure) of fuel to the high pressure pump which feeds the injectors - I don't know if the MK4 is similar?

[Dr G]

Tony1963 said:

I’d be looking at replacing the fuel filter first. It’s a favourite on these cars to forget about.
Then maybe the MAF sensor, another favourite, just gets dirty and tired, gives the wrong readings to the ECU.

I would unplug the MAF before buying any parts. Will throw the engine light on, but will put it into a safe mode. If it runs better this way you've found the problem. May as well clean the throttle body too as they were notorious for getting filthy.

[Tony1963]

Dr G said:

I would unplug the MAF before buying any parts. Will throw the engine light on, but will put it into a safe mode. If it runs better this way you've found the problem. May as well clean the throttle body too as they were notorious for getting filthy.

Agreed

[chazwozza]

I had one that did the same. Replaced plugs, coil packs and maf sensor. Ran fine. Most likely maf sensor imho.

Chaz