Mk2 Mondeo Fuel Injection problem. Any experts help?

Hi all.

I have a 1997 Mk2 2.0 ghia manual hatchback Mondeo. In that red / mauve colour. It's one of the first of the Mk2's. Only 80k on it and I've owned if for the last six years.

What happens is intermittent. When the problem occurs the engine keeps the rpm high with my foot OFF of the throttle. But, if I come to a rest then the engine management sees this and brings it back down to idle, although slightly faster than normal. Often the problem isn't there and it drives normally.

To describe it better... if I'm doing 60 on a dual carriage way I can continue without touching the throttle. If I'm driving through town it's better to drive in 2nd than top because of the pulling. It's not pulling with a lot of power, just as if a toe was still touching the throttle. Does that make sense?

But always, if I slow down to about 2mph or less then the RPM drops down to idle again. It never revs up on its own when not moving.

Could it be a trapped cable, a jammed idle valve or other physical problem? I don't think so because of the intermittent nature and because of the returning to idle when stopped thing. If it was a physical problem it would keep running high when not moving. Also I had the cable renewed a couple of years ago for this very problem. (Yes, it's been a long time but the car doesn't get used much.). Also if it was a trapped cable it would be producing more power than it is because the throttle would be open, not the idle valve. It pulls with so little actual power that it's overpowered by even a gentle touch of the brakes.

I believe the computer is keeping the idle control valve pulled open in response to some (failed or erroneous) signal. When it sees the vehicle speed is very low it releases the idle valve.

So, what part of the FI system would tell the ECU to do this? I'd love to see a flow chart of the logic to see what inputs would make it do this! My initial thoughts are the throttle position sensor. I have replaced this in the past (about 4 years ago). Do they fail often? Or maybe it's the wiring to it?

I have stripped and cleaned the inlet tract. It's squeaky clean, the air filter is clean, the throttle cable is free routed correctly and lubed. The idle control valve is also squeaky clean and is not physically jamming. I can't make it stick by hand. I've removed and inspected the TPS. It seems undamaged and the wiring I can see likewise. Connectors clean. The tag it fits on to is clean and moves freely without jamming.

I've googled for Mondeo faults and found many, but not this one. Where else do I look? I'm in Ferring, West Sussex (south coast) if anyone local has a code reader I could borrow for 30 min's. :)

It's due another MOT in a months time and I'd rather not scrap it or spend a lot getting it fixed. It should be easy, ONCE I KNOW what it is.

Thanks folks.

Reply to
Mike Barnard
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