Troubleshoot a problem for me

Abraham · 27 Oct 2011 at 09:11

I have a slightly worrying, highly annoying problem with my mk3 Golf gti 8v, randomly it will struggle to keep sufficient revs to prevent the engine from cutting out, this can be while idling, or it can be while driving along.
If idling it will either cut out or practically stop (<500 revs) and then manage to start itself again. While driving it seems to be primarily while turning a corner, and can seem like I'm in too high a gear (when I'm not), or the rev counter can just plummet and the motion of the car essentially bump starts itself.

Both of these are very intermittent, I'd experienced both maybe twice randomly in the past 3/4 months, but both have happened a couple of times this week, still very intermittent in terms of I've probably made 20 journeys without anything happening, but it's enough to want me to get it sorted before I do some (more) damage to the car.

I'll be taking it in to the garage tomorrow but would like a decent idea of what it could be. The only suggestions I've had so far are the fuel filter (meant to check whether this was replaced at the last service) or head gasket. Any help will be much appreciated.

Dr Who · 27 Oct 2011 at 09:14

ICV needs a clean, FPR not working properly (massive overfueling at idle/lifting off throttle). They are generic things, not sure if the Golf 8v has issues with those.

Matt82 · 27 Oct 2011 at 09:14

crank position sensor is a highly likely suspect

also the pcv/breather system all connects to the intake system after the MAF. the pcv system is likely to be leaking, those leaks cause it to idle badly.

vacuum hoses

Abraham · 27 Oct 2011 at 09:32

much obliged, anything I could easily check for before putting it in?

Matt82 · 27 Oct 2011 at 09:55

Those breather hoses are right on top of the cam cover so easy to check. They run down the front of the block. Must be air tight. Crank sensor will need diagnostic software to interrogate.

bledd · 27 Oct 2011 at 10:25

These two things have caused the above problem for me in the past with older cars..

Idle control valve could be blocked with sludge -cleaned it out with Wynns car cleaner, and made a new gasket for the ICV from a wheetabix box

(Vectra)

Breather hose split, garage replaced for free (Fiesta)

Scania · 27 Oct 2011 at 15:53

bledd. said:
cleaned it out with Wynns car cleaner

Are you missing a "B" there?

bledd · 27 Oct 2011 at 16:23

Sure am!

Scania · 27 Oct 2011 at 19:45

Abraham · 3 Nov 2011 at 07:43

had it in the garage yesterday, they immediately said it was a common problem on that mk of golf to get the throttle assembly clogged up, so they took it apart and cleaned it up, said it was caked in crap. Charged an hours labour and no parts.
Hasn't fixed the problem

Going to ring and let them know today and get it booked in for next week as I need it over the weekend.

Matt82 · 3 Nov 2011 at 08:37

i thought "clean the throttle body" was an intenet myth. ive not personally known it fix anything

Abraham · 3 Nov 2011 at 09:57

Matt82 said:
i thought "clean the throttle body" was an intenet myth. ive not personally known it fix anything

Well it hasn't in this case either

Matt82 · 3 Nov 2011 at 10:31

im a mk3 golf geek, you should look at the things i posted before you throw more money at dodgy garages again

Burlsey · 3 Nov 2011 at 13:27

You say it happens when turning? Checked the power steering fluid at all?

Abraham · 3 Nov 2011 at 14:23

Burlsey said:
You say it happens when turning? Checked the power steering fluid at all?

First thing I checked. Looking into it I think the heavy steering thing is likely to be unconnected, likely to be a worn power steering belt.

Matt82 said:
im a mk3 golf geek, you should look at the things i posted before you throw more money at dodgy garages again

You posted one thing I could check, which didn't appear to be wrong, and one thing that would need diagnostics to check.
On my model with the AGG engine the lack of an ICV means that the clogged throttle body can cause idling problems. It was a sensible first thing to try, and as it's a very intermittent problem the garage couldn't confirm it to be fixed or not. Not sure how that makes them dodgy, or me throwing money at them?

Matt82 · 3 Nov 2011 at 14:55

sorry if i rubbed you up the wrong way there.

sorry again, but having worked on countless AGGs, loads with idle and cutting out issues, none have ever been cured by cleaning the tb. it just doesnt happen. in fact, excess crud on the tb is an indicator that the breather system is in fact broken as all that crud is being carried through by the airflow that is drawn in through the leak.

did the garage do diagnosis on the ECU and if so did they tell you anything about fault codes?

Abraham · 3 Nov 2011 at 15:13

Matt82 said:
sorry if i rubbed you up the wrong way there.

sorry again, but having worked on countless AGGs, loads with idle and cutting out issues, none have ever been cured by cleaning the tb. it just doesnt happen. in fact, excess crud on the tb is an indicator that the breather system is in fact broken as all that crud is being carried through by the airflow that is drawn in through the leak.

did the garage do diagnosis on the ECU and if so did they tell you anything about fault codes?

They didn't, they'd misunderstood the problem, thought it was just when sat at idle. They're going to have it on monday for enough of a drive to experience the problem first hand.

Matt82 · 3 Nov 2011 at 15:25

if it is a crank sensor, the ecu will keep a log of that problem occuring, "g62 crank sensor implausible" or something along those lines, but im sure they know about all that sort of thing

Abraham · 9 Nov 2011 at 13:47

Matt82 said:
if it is a crank sensor, the ecu will keep a log of that problem occuring, "g62 crank sensor implausible" or something along those lines, but im sure they know about all that sort of thing

You get an e-cookie, it was the cabling to the crank sensor, had worn through, and occaisionally when jolted would flash as a fault on the crank sensor and kill the engine. All fixed now.