RaymondH

My98 with Power FC

Car starts fine from cold and idles at a steady 1300rpm

When warm it hunts up and down between 700-900 rpm. When blipping the throttle it wants to stall unless I catch it. Engine stops at junctions unless I catch it.

When hot it idles at a steady 800rpm but wants to stall or goes down to 400rpm before coming back to 800 if I blip it.

After stalling the engine always starts first touch

Unplugging the MAF stalls the engine (does this check still apply with the Power FC?).
Lambda seems ok going by the lights on my afr meter ie mixture strength cycles up and down.
Unplugging the ISCV recreates the symptoms experienced at warm idle but at 1300-1500rpm even when the engine is idling steadily.
I have checked all pipes, connections etc and all seem ok.
This has happened since shortening the pipework from the dump valve to inlet but shouldn't make any difference at idle however I have tried removing the vacuum pipe from the DV just in case it was opening but makes no difference.

Any ideas? Please?

RaymondH

Pretty please?

brownie1

had the same prob with my 00 wagon changed the maf puka now m8

jap torque

im having same problem mate but no answer really i understood if u unplug the maf and it stalls thats fine mor elikly to be lambda sensor but then i start reading about icv etc and i get lost lol HELP

bluerigster

iTrader: (9)

Try your idle control valve, sounds as though it's this over a MAF as the car is running okay when being driven. Lambda would mean high emissions with no other real effect on idle.

jap torque

can the ICV be cleaned if so what best way to do it??

scoobyman95

it is probley the maf or the idol control valve on the inlet manifold

scoobyman95

it can be cleaned take it off use brake cleaner there is a diaphram and a big rubber o ring clean all that and the inside of the valve do it when it is cold and clamp the cooling lines

Moley

iTrader: (9)

I have the same problem, as was told it could be the MAF or because it has a VTA dump valve

scoobyman95

has nothing to do with dump valve

jap torque

i changed my lambda sensor reset ecu and all seems ok now

RaymondH

Well, I changed the idle valve for a second hand one and it's only marginally better. The surging seems a bit better but the revs still drop too low to about 500 before coming back up to a rock steady 900rpm. On the move it's perfect. The diaphragm was only lightly carboned and dry with a clean ring round the seat so I didn't clean it - if I take it off again to clean can the valve itself be cleaned or is it even necessary? I can just see right through the bottom of the slot in it to the bend on the metal pipe ie there's a small gap between the bottom of the slot and the bottom of the piston or whatever it is inside it so the airway seems clear. The spring loaded bit at the side of the slot moves freely. I noticed with both valves that pulling off the connector plug makes the engine surge up and down between 1300-1500 revs - is this right? I would have thought that it would race at a steady speed or stall. It would be nice to buy a new valve in case I've replaced a duff one with another but these parts are too expensive to buy on a hit or miss approach.