Revs dropping, engine dying when dipping clutch at roundabouts, traffic lights etc.

[mike_on_the_mike]

Hi all,

This might be a familar sounding issue as I've searched the threads and come across this problem with other drivers..

As in the title, when the engine's warmed up (doesn't happen when cold) and I pull up to traffic lights, roundabout etc. and dip the clutch, then revs drop off almost to zero before either suddenly jumping up to 750 where they should be OR dropping off completely and stalling the engine.

I've tried cleaning the MAF which didn't seem to do anything. Then I got a new MAF from Scoobyworld and put that in. I did the simple ECU reset by disconnecting the battery, holding the brake lights on for a while and leaving it overnight.

The issue is still there so two questions:

1. Would that have actually reset the ECU or do I definitely need to do the black/green plugs.

2. Many mention the idle air control valve however I've not found a guide to cleaning it on my particular car. Also, everyone says to change the gasket but I can't find a gasket that says it's compatible with my car..

It's an Impreza Turbo 2000 MY00 saloon

Engine bay looks just like this:


Any help would be much appreciated

[Bolesroor]

I recently had an issue with my 05 blob ticking over high then hunting revs turned out to be idle control valve, this was cleaned and replaced with new gasket problem sorted but by Carnetix.

Currently have an intermittent tick over issue when warm on our jdm wagon, I've been advised to change the maff 1st, problem is it is an orange label 1 and having trouble sourcing without being robbed. YouTube show how to re solder the connections as the post claims this often solves the issue, haven't had time to check this out so cannot comment.

Hope you get it sorted

[Scott.T]

Idle Speed Control Valve (ISCV) which is the silver cylinder type thing plugged into the side of the inlet with the black connector between the throttle butterfly and the intercooler.
Try cleaning with WD40 or carb cleaner, but don't manhandle the spindle too much as they can fall apart.
A 2nd hand one from a good breakers should be about £35.

[Ginola]

Originally Posted by SilverSurfer

Idle Speed Control Valve (ISCV) which is the silver cylinder type thing plugged into the side of the inlet with the black connector between the throttle butterfly and the intercooler.
Try cleaning with WD40 or carb cleaner, but don't manhandle the spindle too much as they can fall apart.
A 2nd hand one from a good breakers should be about £35.

+1. It will be this 99%!

You will need s new rubber gasket £2 or £3 from importcarparts

[mike_on_the_mike]

Originally Posted by Ginola

+1. It will be this 99%!

You will need s new rubber gasket £2 or £3 from importcarparts

Thanks guys. I've been reading in other threads that this needs a new O ring when being cleaned instead of a gasket as gaskets are a different type of IACV? I can see the orange O ring in pictures of the IACV but can't find anywhere that does spares.

Any chance this O ring pack from Halfords would contain one suitable?

http://www.halfords.com/motoring-tra...d-o-rings#tab1

Otherwise does anyone know where I can get these from?

Also, there are plenty of cheapish IACVs on ebay for around £30. Would anyone trust these?

Thanks for the help!

[Scott.T]

It's been along time since I had mine out to clean (ISCV obviously), but I don't recall anything significant about the o-ring. Any off-shelf o-ring kit would be fine.

Alot of the Ebay ones are Legacy/Forester and/or different partnumbers when I last looked, so make sure you pick the right Part Number 22650AA240

This seems to imply it fits : http://www.ebay.co.uk/itm/Subaru-Imp...item4ae6089adc

[C. J.]

Pm'd you there's a trick that means you can re use

[Scott.T]

Originally Posted by C. J.

Pm'd you there's a trick that means you can re use

Is it a secret trick then ?

[C. J.]

Yes

[C. J.]

I can't be arsed to type it so pm him my mobile

[mike_on_the_mike]

Cheers for the chat CJ. As we discussed, mine is the classic model so the new age gasket doesn't apply. Thanks for the help though.

In the end, I found a perfect o ring replacement in a PlumbSure mixed pack from B&Q.

Took the ISCV off and it was caked black. Some WD40 and a pile of blackened Q tips later and it and the chamber are looking a lot cleaner. All replaced but I'm not sure it's fixed, although I haven't done a long distance to really test it. The revs still drop low and come back up again, but hasn't stalled yet. Maybe the IACV unit is too gunked up inside so I'll look at replacements on ebay.

[MIDLIFE]

No expert, but is that a vta valve you are running? If so they can cause lumpy tick over if they leak.

[mike_on_the_mike]

Originally Posted by MIDLIFE

No expert, but is that a vta valve you are running? If so they can cause lumpy tick over if they leak.

No idea what dump valve it is; it was fitted by the previous owner.

Also, the tick over is not lumpy, it's dying revs when dipping the clutch which is the problem.

[mike_on_the_mike]

The saga continues..

So I ordered a replacement IACV from ebay however the one that turned up had a different black valve end to the one I took off the car. More pointy than the blunt end on the existing valve, so that's going back.

The one I have now is from worldcarparts.co.uk. Looks exactly the same although without the part number sticker. Identical otherwise except that the valve and spindle are greased and can pop out from the solenoid.

Is this normal? I can push the rod/valve in to the solenoid and if I'm gentle then it stays in, however it can and does pop back out if shaken.

As I say, is this normal? Do I just gently push it in the solenoid, turn the ignition on and off a few times and it sorts itself out? I could give it a try but the car is in a lockup in another part of town so thought I'd post here before driving over there only to find out I've got another part which won't work..

Thanks for any help!
Mike.

[Gixer]

My old MY99 STI developed the same problem when I repaired a split air pipe on the boost gauge.
If was fixed by replacing both the MAF and the lambda sensor.

[andy-m]

Originally Posted by mike_on_the_mike

No idea what dump valve it is; it was fitted by the previous owner.

Also, the tick over is not lumpy, it's dying revs when dipping the clutch which is the problem.

Is it any time you dip the clutch? or just as you are stopping and dip the clutch?

i had an early forge valve on mine (V1) and it was a known issue that they could leak on idle (They revised the design for later manufactured ones). it gave the same symptoms. I used to use the heel-toe braking method to keep it from stalling as I pulled up to stop at the lights !

take it apart and put some red lithium grease on the piston. It doesnt fix the problem, but it will make it go away long enough for you to identify it as the cause if it is letting by.

[mike_on_the_mike]

Issue is still happening and it's driving me crazy.. Very unsafe for the engine to suddenly die pulling up to lights, t-junctions etc.. I've tried several new IACV units, new MAFs, new lambda sensors.

@andy-m, do you mean the piston on the IACV or actually in the engine? Bit above my experience level if you mean the engine, and I've nowhere to do that sort of work anyway..

Other threads have suggested cleaning the throttle body in case it's gunked up and sticking. Does anyone have a guide to doing that on a Classic Impreza Turbo? Do I just need to remove the intercooler to get to it or remove the entire throttle body?