My wifes Ka has an intermittent problem where the engine revs between gear changes and when you come to a stop at the lights. It only revs for a few seconds, then goes back to a normal idle. I've checked throttle cable to make sure it's not sticking, and it isn't. Today, I went over to my dads and it revved between every gear change and when i stopped. When i pulled up outside my dads it was revving really high, and I turned the ignition off before I stopped. The engine was off for two minutes, and I got back in again to go home and it behaved perfectly all the way....

When you take your feet off all the pedals, and it's in gear, it pulls you along.

I'm thinking this may be either the lambda sensor is faulty causing the ecu to think the engine is lean, or the water sensor not working properly, so the ecu thinks the engine is permanently cold.

Anyone have any other ideas?

It could be a number of things but check the simple stuff first.

How old is the KA and whats the milage

Has the throttle return spring broken.

Has anything been touched recently ie
serviced.

Check any vacuum hoses

if no of these bits then

Check the tps they are a wire potentiometer and do wear out just unplug and rev car again. its next where the throttle cable attaches.

If not that remove air inlet hose between the tps and MAP sensor which is next to the air box rev again and see what happens

then re connect and unplug MAP sensor and see what occurs.

Its just a matter of trial and error odds are you need a new TPS

I am sure there is a common fault on these things. It is the connector on the Throttle pos sensor plug bad connection, I think you have to fit a new plug. I was reading about it on friday.
Steve.

All fords with TPS fitted seem to suffer from this.

I know of a 1.25 zetec Fezzie, and a 1.3 fezzie (same engine as the KA) currently doing this my Escort misbehaves and a neighbours Mondeo .

My Garage/ Mot mate says he gets these on a regular basis.

Seems they wear out from idle to about 1500 rpm.

Go down a breakers and you will see in any decent wrecks this are the first bits missing.

John

Thanks for your suggestions. i didn't think about the TPS. I'll have a look in the morning.

Mike

it should be the throttle system

because if it was just petrol the engine would run lean or rich and thats not pulling or driveing the car...
also labda margen is limited..

the only way of BHP creating is with the right amount of air and petrol..

sow maybe its the bearing of the accelerator

etc..

Tks

Another time it might do it is if you ver change into Neutral and cost down say a big hill. My 1.1 CFI (Central Fuel Injection) fiesta does it, bodged up carb with 1 injector!

I'm pretty certain its not mechanical cos whatever you do to the pedal or even the throttle arm itself under the bonnet it makes no difference. There's no Fast Idle air bypass valve or anything complicated on mine so i'd guess their right with either a vaccume hose or a throttle pot being at fault.

Its the the Idle Control Valve on the front of the inlet manifold.
Its held on with a couple of bolts with 10mm heads. You'll see when you get it off how sooted up it gets. Just take it off, clean it with carb or brake cleaner and refit
It is a common fault easily fixed. My wife has one and got this off a Ka forum.
Steve

TPS is a major problem o this model -- some only last 20,000 miles.

Just about any tps you get from a breakers will be worn in the idle to 1/4 throttle range.

Only real way to check a TPS is to put an Oscope on the output -- output should be dead smooth.

I've just fitted a spare throttle pot i happened to have knocking around. I won't know whether it's worked until tomorrow when my wife gets back from work, and isn't in a bad mood

Well, the wife came home with a smile on her face. She said the car has been 'transformed' and is more responsive. So, thanks again for pointing me at the TPS