16 replies to this topic

[silver_toes]

Any advice would be much appreciated.

1997 cooper MPI

Idle sticks at 2000 rpm on first start up in the morning
After driving about 2 miles (or when the engine is warm) I pull over, turn the engine off, turn it back on again and it settles nicely at 1000rpm

If I don't turn the car off and on again (I know I sound like an IT help desk) the engine sits at 2000rpm whatever temp it's at

Things I've tried so far
Checked hoses
Checked Throttle body for cracks
Checked throttle cable's not sticking
new IACV
new ambient air temp sensor

It's annoying as I have to stop a few minutes in to every journey to sort this out. Is it worth changing the the thermostat ?
My next step was to change the thermostat and flush the coolant. I'm running out of ideas now.

Cheers

Liz

Edited by silver_toes, 06 February 2013 - 08:40 AM.

[Fast Ivan]

It could be that the throttle body is warped, if you rule this out along with the cable and cracks then it would point to information that the ECU is or isn't receiving.
Your next step would be to hook it up to diagnostics machine with someone that knows how to use it (i'm not saying you don't). You are not just looking for faults to show up but you will need to be looking at and analysing the live data.

[OfMini&Men]

is the choke sticking on? not cutting back off but does when engines turned off? as its getting now power?

[Fast Ivan]

the idle speed is controlled by the ECU based on the information it gets from the sensors

[silver_toes]

Hi Rob Mac. I've had a good look at the throttle body and it doesn't appear warped. The butterfly thing (sorry don't know the name) seems to close up properly. The throttle body is a plastic one, I guess I could replace it with the metal version but it's very expensive.

I did have the car hooked up to a diagnostic thing by a garage. It reported the the ambient air temp sensor was reading -270 degrees. I replaced the ambient air temp sensor and it seemed to fix the problem for a few weeks. Now the problem is back.

The other problem is that I need to get it to a garage and get it hooked up to diagnostics without turning the engine off from first start of the day as the problem is not present when you start the engine up after it's warm.

Thanks for the advice. I'll double check the hoses and throttle body at the weekend.

Cheers

Liz

[nev_payne]

Throttle body may not look warped, but it's enough to throw the throttle position sensor. Could be that in warping it's pulled up from the inlet manifold causing an air leak underneath. If you think that's expensive to replace, there's plenty more electronic wizardry that's far more costly.

You could try resetting the position sensor - set the ignition to stage II, pump the throttle to the floor and off 10 times and set the ignition back to 0. Start the engine again and see if that affects the idle.

[silver_toes]

If the throttle body was warped, why would the issue go away when I turn the engine off and on again ?

Cheers

Liz

[nev_payne]

Always worth checking. Maybe the case that the throttle position sensor is faulty. I would also have the IACV (Idle Air Control Valve) cleaned and checked - this is on the far left corner of the inlet manifold as you look into the engine bay. As you've not got a case of low-revs and grumbly idle it should suggest your vaccum feed to the brake servo is fine so that's one thing to tick off.

[silver_toes]

OK, apologies for the update on this, the phrase 'flogging a dead horse' springs to mind.
I promise not to post anything further on this issue and just take it to a mini specialist garage if I can't sort it after this.

Nev_payne, I've swapped the iacv out for one I know works - no difference though.

Whilst surveying the engine bay tonight i did notice that the metal clips on the air filter housing have rubbed against the wiring loom which runs across the bulkhead. part of one of the wires has been exposed (only by a tiny bit) and only one wire in the loom

Could this be part of the problem. I've had a few false starts on thinking that i've fixed this. After replacing the IACV and ambient air temp sensor the problem seemed to go away for a few days. Both these correspond with taking the air box off for access. I'm wondering if moving the loom makes the problem go away for a few days until it settles back on top of the filter box.

What are people's thoughts on this or am i just clutching at straws now ?

cheers

Liz

Edit: this still doesn't explain why the problem goes away when I turn the car off and on again

Edited by silver_toes, 07 February 2013 - 07:19 PM.

[Fast Ivan]

no you are not just clutching at straws - that could well be your problem. In any case its worth repairing because first of all you can rule it out, and its just not good to have exposed wires; if it isn't your problem it will soon develop in to one.

[nev_payne]

I've also had the air box that exact same thing. You could very easily trace exactly what that cable does with the MPI wiring diagrams available on here (or one of us will have a butchers!) What colour wire(s) are they?

[silver_toes]

I was looking at the problem via torch light last night so it was difficult to see the colours of the wire affected. I think it was a wire with two colours (yellow and purple possibly) but I can't be 100% sure until I can see it in the daylight properly tomorrow.

I'll take some pics and post them up tomorrow.

thankyou for all the advice by the way, it is very much appreciated. I am still on a massive learning curve with this car but definitely enjoying it.

[silver_toes]

Just looking at the Rover workshop manual wiring guide and I find this. Looks like the MAP sensor and TPS use the yellow/purple wire.

Manifold absolute pressure (MAP) sensor
The manifold absolute pressure sensor is mounted directly on the inlet manifold and provides the ECM with an accurate representation of the load placed on the engine. This allows the ECM to adjust the quantity of fuel being injected together with the ignition timing, to achieve optimum fuelling of the engine. The MAP sensor achieves this by detecting pressure variations inside the manifold, then converting these variations into graduated electrical signals which are monitored by the ECM on RG and YP wires to determine engine load. Earth supply is on a KB wire.

Throttle position sensor
The throttle position (TP) sensor is a potentiometer attached to the throttle housing and is directly coupled to the throttle disc. Closed throttle is detected by the TP sensor which initiates idle speed control via the idle air control valve (IACV). The TP sensor receives a 5 volt supply from the ECM on a YP wire and is supplied with an earth on a KB wire. The sensor then provides a signal which is proportional to throttle disc position on a YG wire to the ECM.

[nev_payne]

Right - throttle position sensor, high revs, and the yellow-purple wire. I think you've found your culprit!

Nice work, I recommend you get some insulation tape or heatshrink in there and tuck the loom further back into the bulkhead.

Edited by nev_payne, 08 February 2013 - 11:26 AM.

[silver_toes]

Boooooom......

50 pence worth of electrical tape seems to have sorted this. Thanks everyone for your responses.

Cheers

Liz