idle revs yet again!!

[giles]

Hi Folks,
Just run my mini up to temp in the garage and all fine until it got warm (after 20 mins or so the fan kicked in). While sat in the drivers seat I blipped the throttle and then the revs hung and stayed at 1600rpm then after another blip they rose and stayed at 2500rpm. Even after trying to drop them manually by putting in gear with brake on and lifting the clutch it would still rise again to 2.5K.

Any idea what's going on? In normal driving it's fine unless sat in traffic in warm ambient temp.

It has been suggested in the past that it could be to do with the temp sensor wiring connector. Fan all seems to work fine, kicks in shuts off no issues.
Thoughts?
Cheers, Giles

[bignyg]

What car are you running? i assume its a SPI or MPI in which case try cleaning the throttle body as they gum up, there should be a small bleed hole in the housing by the butterfly which may have clogged. Its a good place to start with no cost involved

[giles]

Thanks for that.
How can I clean the bleed hole? Cocktail stick?! Do I need to remove the air cleaner?
Cheers, GP

[casbar777]

Have a look at the stepper motor (IACV). They have a habbit of breaking, check the pipe from the throttle body to the IACV, if its split or the bottom of the stepper motor is brocken off, this will effect idle revs.

This was the issue with my mpi, although the stepper motor is like rocking horse sh1t when trying to find a replacement, you I hope its not that

[hawaiianblue]

The stepper motor is the same as the K-series rovers i think. Carb cleaner will flush it out. Also check the wiring harness in that area for chaffing.

Although a common cause of this problem on MPi's is the plastic throttle body warps and cracks with heat. Causing it to suck air and/or pinch the throttle spindle making it stick open.

The fix is to replace the throttle body with one of the alloy ones from Burlen fuel systems. Rover did replace them with alloy ones very very late on in production, but so late they are rare. If the fault surfaced under warranty then you got an alloy replacment.

[giles]

I've got an alloy one

[Graham Bichard]

I had a similar problem with my car. Changing/cleaning the contacts on the sensor on the thermostat housing seemed to cure it!

[hawaiianblue]

Originally Posted by giles

I've got an alloy one

Well that rules that out then.
I ended up with a stalling problem on mine (oposite of your problem) the wiring harness had chaffed through on the clutch master cylinder.

[hanlminiman]

Well how about that and I thought my problem was unique? Exactly the same happened to me in my 1997 car at the start of the Lord Mayor's show in London in 2001 after I returned form the Italian Job. The AA sorted it out though and it still runs well with the additional protection on the wires in front of the master cylinder.

[casbar777]

Not sure if the stepping motor is the same as the K series. The K series ones I've seen, don't seem to have the elbow on the bottom, that the pipe connects too. They look like they bolt into the manifold instead of on the side of it. Might have been looking at the wrong bit though. The electrics may fit, but its normally the plastic elbow that cracks off, leaking air, not the actual electric bit of the ICAV