High rev's when starting

[SteveB]

1999 S reg with 90,000 miles on the clock
When I start the engine from cold it instantly revs to 2500 revs and if I press the throttle it ticks over at 3000 revs
After driving for about a mile it settles down to the normal tick over and drives normally when starting from hot it ticks over normally
It has only just started doing this can anyone give an explanation an a cure as I do not think the engine likes these sort of revs from cold.

[c_w]

Could be the idle control valve or it could be something like the throttle is sticking open (before you start it from cold make sure the throttle is fully closed by opening the bonnet and making sure the throttle is fully closed).

[SteveB]

I have checked all the usual areas the throttle is fully closed and lubricated
I will check the Idle control valve are they servicable or do you just by a new one and throw the old unit away

[c_w]

Just had another thought; there is some kind of air pump attached to the bottom of the engine that is run by the fan belt and has pipes (one going to the airbox I think, and the other the exhaust), I think this must be some kind of device to keep cold emissions down. Not sure if this could have a fault/loose pipe?

[brady]

i know this isnt a proper fix but if u give the throttle a blip it will settle back to normal idle, thats if its annoying u, dunno what the actual problem is tho

[pies]

sat in traffic this evening i was wondering about the very same problem.

the car doesn't always return to idle smoothly, sticking on 1000-1200rpm unless i blip the throttle again.

have already tried lubricating the throttle mechanism, which definitely seems to have loosened up the pedal action when heel and toeing.

However sat at a standstill in traffic the revs occasionally surge to 1000rpm+ which can't be a sticky throttle.

What's involved in sorting out this idle control valve? DIY job with a spanner or megabucks at a garage?

[BMWboy]

had a similar thing with mine, after replacing the idle control valve it turned out to be the vanos .

[brady]

anyone ever notice the way everything ends up bein related to the vanos!

[p 5ary]

anyone ever notice the way everything ends up bein related to the vanos!

beat me to it lol :lol:

[David1975]

Hi,

I have noticed my S50 doing exactly the same thing the last couple of mornings. Also notice when sat about 40 in 4th and my foot is just resting on the accelerator i sometimes but very rarely feel a momentory lack of power like when you are just about to run out of petrol. At first i thought i had just passed over a bump in the road which made my foot breifly lift of the accelerator but after a few times i am not too sure. Obviuosly i am thinking that this and the high rev's upon starting maybe related????

Any ideas??

Cheers guys

David

[SteveB]

Thanks for all the feedback
I found the problem Saturday morning
I removed the air filter box and the rubber hose connecting it to the cast inlet manifold.
By the dipstick tube there is a couple of vacuum hoses that connect into a small valve with a 'T' piece one side has a blanking cover this was split and so was the tube feeding to it
I replaced the tubing and the blanking plug It now starts correctly and runs smoother without the hesitation.

[David1975]

I will check mine out this weekend. Hopefully its just a similar problem.

cheers

[spunkym]

Well done Steve and thanks for reporting back - could be very helpful to other people suffering from similar problems in the future.