Diagnose my car fault please

Morning

Noticed engine being odd over last few days. It’s a 2000 1.8 Focus Zetec.

When I let the car role in neutral (traffic jam down a slight gradient) the revs increase to 2000 rpm. When car comes to a halt the revs drop to normal idle speed.

Is this a sign that the clutch is on the way out?

We’re hoping to keep it running for another year as money is very tight. Just spent £500 on breaks repair and new tyres and don’t want another massive bill.

It’s going in for a MOT on Monday and don’t know if I should mention it to the garage or, ignore and hope for the best.

In neutral, I don’t think rolling down the hill should have any impact on the clutch. You can normally tell if a clutch is starting to go by putting it in fourth and accelerating briskly from a slow speed. The revs should go up a lot as the clutch slips and the car fails to move, then drop as the clutch bites.

Not sure why the revs are climbing on their own though.

Maybe. The accelerator pedal is fly by wire, and the electronic bits in it start breaking down. Our ’99 Focus started doing strange things, slight hesitation under load at times, then the idle would go up randomly.

Second hand pedal unit for £19 off ebay and 15 minutes with a spanner and it was fixed.

Idle control valve possibly needing a clean, or throttle position sensor?

I had something similar on my car……was a “rebreather valve” and it cost £120………

When I let the car role in neutral (traffic jam down a slight gradient) the revs increase to 2000 rpm. When car comes to a halt the revs drop to normal idle speed.

Doesn’t say clutch to me.

Or accelerator pedal / TPS – you’d get the problem both moving and stopped then.

Idle control valve possibly needing a clean?

I’d guess idle valve, too.

Engine electrics will usually raise the idle revs in neutral, when you’re moving, to make an easier gear change. But not right up to 2k. This kind of suggests the ECU is opening the valve “a bit” and the valve then sticks open. When you stop, idle comes back to normal as the valve isn’t sticking when (nearly) close.

Possibly a faulty clutch pedal switch. Had this with my car in the past.

Had this on a Ka. ECU got confused once in a while. Disconnecting the battery for 15 minutes sorted it.

As Murray says always worth disconnecting the battery. Some faults latch so show even when the fault itself clears. Does sound like idle speed control valve could be the problem.

If it is beware of it faltering in the other direction. I had a 97 escort (same engine I think) which would cut out as I depressed the clutch to change gear going into a turn. That led to loss of power steering and nearly hitting a tree!

as i remember the part wasn’t too expensive and it’s a pretty easy change. I didn’t bother trying to clean it up.

You’ve all settled my fears that it was going to explode in a rad ball of fire and money, thank you.

It’s been a faithful friend for 10 years. I think it overheard us talking about scrapping it and is acting up.

‘Air bypass valve’ is £110.20 from a main dealer. Should get a pattern part for about half that. Part Number: XS6U-9F715-AA (probably)

As stated above Throttle Position Sensor, can be thrown out by dirt and fluff stuck to it. Idle Control Valve can get gummed up and just need a clean.

http://www.ebay.co.uk/itm/Air-By-Pass-Valve-Idle-Speed-Control-For-Ford-Focus-1-8-16v-2-0-16v-XS6U9F715AA-/301413286531?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item462da1c283%5B/url%5D

£20 on e-bay. If it is the problem.

Or.

If the valve is just dirty, remove it, and clean it with a stiff brush and some petrol for approximately £0.