Car revs at 3000 rpm at idle

[Quaser]

Hi guys -

Need a bit of help for my neighbour - it's a 325i touring auto and he was driving at normal when the car suddenly shot up to 3000 rpm and it stays there.

He called out the AA and they advised the idle control valve - when the valve is unplugged, revs drop to around 1700/2000 rpm but shoot back up to 3000 when plugged in.

All hoses look ok- is it the idle control at fault? I would have expected to hunt rather then sit at 3k

[Quaser]

anyone??

[Brianmoooore]

What's the engine ECU type number?

[jimbom30cab]

If you unplug the idle valve and hold shut the TB butterfly, what does it idle on then?

[Quaser]

just under 2000

[jimbom30cab]

Sounds like too much fuel, is it running very rich and the exhsust stinks of petrol

Have you tried another ecu?

[Quaser]

i dont have another ecu to try - exhaust doesnt stink any more then usual

[Grrrmachine]

I'd suspect the TPS, but I dont know the details of the fancy 6-pin auto ones. Maybe unplug the TPS and bridge the pins that send the idle signal to the ECU, and see what happens.

[Rtaylor2208]

This may help with the TPS, this was the advice I got from Brian:

http://www.e30zone.net/modules.php?name ... highlight=

[Ant]

auto has a load sensor for the autobox, the ecu does not use this info and only get the closed and WOT signals as per std 3 pin units.

if its a 380 ECU these can fail the idle control circuit over time and cause similar idle control issues however 3K is high for that failure,

Look at the breather that runs TB to R/cover for a split , or failed NRV on the servo side...

HTH

[Quaser]

Ill have a look at that cheers

(Whats an NRV?)

Q

[Speedtouch]

Non-return valve (in between the brake servo and inlet manifold).

[Quaser]

apart from replacing the NRV, is there anyway to test it?

[Speedtouch]

Remove the hose/valve and blow/suck through it, to check the valve only allows air to pass in one direction.

I take it you've checked the obvious, that the throttle cable is intact and adjusted correctly?