ABY coupe won't hold idle

[rynaqui]

Currently trying to diagnose an issue with my S2. It has recently been idling erratically at times on occasion also turning itself off. Now a few days ago I got boost cuts on WOT but not on part throttle.

What I have noted is that when I start the car with the isv unplugged it seems to hold idle if a bit unhappy but when plugged in it doesn't idle at all unless you rev it. Coil packs are fine but haven't checked plugs yet. MAF is also fine just replaced recently and the wire is in tact. Just hoping to get a bit more direction perhaps

[mike74]

have you done a fault code check? Might be a good idea to do a boost leak test too

[Rikki Kitto]

Mine did similar changed and swapped all sorts turned out to be a build up of carbon deposits in the throttle body, had it soda blasted and all is now well

[newsh]

Wash the ISV out with WD40 or GT85
Usually works for me, although it happens less since I fitted the catch tank.

[rynaqui]

New ISV installed, new plugs, coils are good. When the ISV is plugged in the car will still not idle and will stall immediately. I ran the car without the ISV plugged in and the car boosts on part throttle but not on WOT which indicates a boost leak/vac leak. That's my next port of action then however the old plugs were definitely past it, the new ones made a big difference.

Also will check the throttle body for carbon deposits. Thanks guys! Will keep you informed with my findings

[newsh]

Does sound like a leak
Maybe a leak in the PCV system or the one way valve is dead

[ericd]

what about G62 (water temp sensor) at rear of engine

[QuattroFever]

Interesting. Would that throw a mixture adaption code?

[ericd]

Interesting. Would that throw a mixture adaption code?

usually it'd get a specific code relating to the sensor, the symptoms caused by G62 failure do mimic those other devices, but lumpy,unstable idle is one of it's traits, the sensor's about £12-15 and even though its a bit of pita to get to (10 mins), it's easy straight forward if it fixes it..

[rynaqui]

So have just done a boost leak test and found a very slight leak to the inlet manifold, will attach pictures to show which area was leaking. Should I replace any sensors whilst there? Thought it may be a good opportunity whilst I've removed everything in the area.

Also where is the G62 sensor exactly? Have already removed muich of the rear part of the engine bay so not a bad idea to replace that whilst there too. Cheers for all the input guys

[rynaqui]

Part leaking attached in the picture to show.

[newsh]

ABY coupe won't hold idle

Engine ECU temp sensor is the one with the white connector just below your blue ground crimp

[newsh]

Was the carbon can valve leaking, the one with the wiring plug?
Replace the PCV valve (one way valve) while you're there.

[rynaqui]

No leak from there but decided am going to source a new one whilst there, also ordered a new G62, new PCV as advised as well as the crankcase breather valve, may as well go the long haul and make sure everything is done right once..

Just learnt a fair bit more about my car once more, thanks again!

[andyg plym]

Few years ago I had an s2 coupe and similar happened I did the usual of swapping parts like you've done but eventually noticed there was no voltage at the wgfv and isv which from memory run off the same section of loom in the end bo and I had to hard wire from the fuse box to the wgfv and it worked.
Check all fuses are good