Rover 25 idle speed MINDF*** HELP, BEFORE I GO MENTAL

[xbo11ox]

Alright gang does anyone have any bright ideas about this? Its driving me mental and causing me to go into a depression as it continues to waste what little garage time I get nowadays, stopping me working on 'old stuff'.

Basically my Rover 25 van (04 plate, 1.4 K-series) ticks over at about 1800rpm minimum. It you rev it above 4000 it stays at that speed despite the throttle butterfly being fully closed!!!! You have to switch the engine off and back on again to get the speed down. I have tried everything I can think of and failed to cure it.

I have checked the manifold for air leaks - theres defo none, as if you block off the air passage into the idle control valve, it stalls immediately.

I've changed the throttle position switch for a spare, which made absolutely zero difference to anything. I've tested it with a multi meter and although i don't know what the resistance should be it increases steadily with throttle opening and the two TPS's I have behave similarly.

Changed the idle control valve as well for a SH spare, again no difference. If you disconnect the plug from the ICV it makes absolutely no difference either to how the engine runs. The strange thing is, if you take the plug off the ICV and connect it to a spare one held in your hand, then rev the engine, you can see the ICV responding - it opens at the engine revs up the closes as the speed comes down. If you take it right off and attempt to blow through it, you can't, so its defo not jammed half open.

Changed the inlet manifold pressure sensor, that achieved nowt. The engine starts, warms up and runs a treat, no spluttering or other nonsense and no EML on the dashboard.

Another thing I've noticed is when you switch the ignition off you can hear the ICV humming for 5-10 mins afterwards.

Basically all the elements that are necessary for it to be able to idle at the proper speed seem to be OK yet the system is simply not behaving itself with the result that the idle speed is all over the shop.

Please help!!!! I will paypal a pint of beer to anyone who can make a suggestion that leads to me getting this sorted.

Cheers!

[speedy88]

Is it possible that ICV is being temperamental and is jamming open occasionally - you've just been unlucky not to see it? I've not worked on these cars but I know on the Williams engine, dousing the ICV in paint thinners overnight and spinning it clockwise and anticlockwise quickly between your palms (like a firelighting technique) to make the ICV clunk open and shut was a surefire was to make sure they were free.

As far as leaks go, I take it you've been around the manifold/hoses spraying easystart everywhere?

[stealthstylz]

Throttle body spindle is jammed according to my mate who's an MG specialist.

[xbo11ox]

Defo not that, I've had the throttle body off and cleaned it all, its as smooth as the proverbial baby's backside and snaps shut like a champ. One point about it is i have ditched the restricted 84ps throttle body and fitted an MG ZR 105 effort.

[theheap]

To make it rev it needs air. Throttle body closed and no vac leaks and still holding 4000 rpm. I'd say vac leak.

[xbo11ox]

All the air it's ingesting is coming through the ICV - if you manually close that off, by nipping its air pipe or covering the aperture with your finger it stalls immediately, which suggests there is no other source of air?

[Battles]

Nov 15, 2013 10:52:04 GMT xbo11ox said:

All the air it's ingesting is coming through the ICV - if you manually close that off, by nipping its air pipe or covering the aperture with your finger it stalls immediately, which suggests there is no other source of air?

This points to the ICV. As you say, it seems to be the only source of air.

Nov 14, 2013 23:18:46 GMT xbo11ox said:

Changed the idle control valve as well for a SH spare, again no difference. If you disconnect the plug from the ICV it makes absolutely no difference either to how the engine runs. The strange thing is, if you take the plug off the ICV and connect it to a spare one held in your hand, then rev the engine, you can see the ICV responding - it opens at the engine revs up the closes as the speed comes down. If you take it right off and attempt to blow through it, you can't, so its defo not jammed half open.

When you test the spare ICV, do you have it on the car or plugged in in your hand all the time?
Do you get the revving symptoms when you have the ICV plugged in and in your hand?

[froggy]

Where is the map sensor on this ?

[xbo11ox]

It’s on top of the inlet manifold, left of the middle if you’re stood looking at the engine

[silver63]

Does this model have the plastic manifold?If so check the earth lead under the gearbox end of the manifold as this can make them do really strange things as they try and find an earth path.

[155ringman]

Try the water temp sensor that reads to the ECU. It should be under the stat block.
Failing that, a dead or gummed up lambda can give the same sort of issues..

[xbo11ox]

Oh aye, forgot to mention that, i have replaced both temp sensors with brand spankers! Typical innit.

[155ringman]

There's two lambda's, try unplugging each in turn...
Or swap one out. Manifold one first.

[Dorset_Clive]

Probably telling you things you've tried, but when you changed the TB did you change the cable too? I haven't done it myself as I've always had full fat 103bhp engines, but my mate did on his and the throttle cable is DEFINITELY different between the two. I don't know if it is causing the problem but an idea. Try disconnecting the cable and just use a finger on the TB to rev it and see if you get the same issues.

The other thing is to 'reset' the ICV. Turn the ignition on but don't start the car. Press and release the throttle to full open five times (within 10 seconds iirc). You should hear the ICV rattle a little as it fully steps from closed to open and back.

If you press it nine times (iirc - check on a Rover forum) it does a 'complete' ECU reset including the ICV.

You might find one of these do the trick...

[bortaf]

Not specific to the car but ni on all moderns have a learning ecu that takes a few miles to relearn after swapping parts (especialy idle control), a few mile drive usually sorts out idle problems after messing with bits, vauxhall seem to the most sensative IME ?

[retrowrongun]

Have you recently had a head gasket done or removed parts and reffitted them at all ?

Only ask as had another rover once of a similar era that was doing something similar and after a long while found that the throttle position sensor ,and the camshaft sensor have an identical wiring plug .......am sure you can tell we're this is going lol

Anyway it was found that when he had the head gasket done prior to his idle issue they had put connectors on wrong way round TPS switch wiring was plugged into the camshaft sensor and vice versa


Long shot but worth a try and please do let me know if the wiring plugs are the same on your car as it may just be possible that's what it is

stepper motors always go faulty and stick also 

[xbo11ox]

I read about these wiring plugs yesterday, so came down the garage today to check mine out. Guess what? They were on back to front! I swapped em over and its purring like a kitten! Flipping unbelievable, the amount of time i have wasted mucking about with that doesn't bear thinking about. Anyway its running super sweet now so next stop MOT station! Cheers everyone!

[retrowrongun]

Nov 17, 2013 15:51:16 GMT xbo11ox said:

I read about these wiring plugs yesterday, so came down the garage today to check mine out. Guess what? They were on back to front! I swapped em over and its purring like a kitten! Flipping unbelievable, the amount of time i have wasted mucking about with that doesn't bear thinking about. Anyway its running super sweet now so next stop MOT station! Cheers everyone!

Nice one mate glad to help hahaha take it my virtual pints in the post then lol ,

pjust glad its sorted

[Battenberg]

This is what I love about the forum, logic and help to overcome what we think is correct.

Xboll

How nice would it be to cruise down to France in the maser, in all fairness in pub talk can we say we have a Maserati ?

As many on here want, get shot of the van and get back on the maser!

Much love