Ford Mondeo - Idling / Revving Issues

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Tue 6 Oct 2015 13:56
Ford Mondeo - Idling / Revving Issues - nick3young

Hi All,

My Ford Mondeo Mk3 (54 plate) has been behaving strangely for the last few months. These are the issues:

  • In the morning, revs often drop to zero at the first junction and the car cuts out. Sometimes it might just hang on before pulling back up to 1k revs (needle goes up down like a yoyo though)
  • Once warmed up, revs take on a mind of their own. If I pull up stuck in traffic, revs can fly up to 3000+ for a couple of seconds before dropping to about 1.2k.
  • Also, I seem to have inherited automatic cruise control. I can be driving along at 40mph... take my foot of the pedal and it continues at that speed. Sometimes the revs even pick up and the car starts accelerating (quite dangerous I guess!)

Here's what I've done:

  • Taken it to the garage - the mechanic ran the diagnostic test on it and no faults came up on any of the sensors. He's not sure what could be causing the issue... but he said to try these two...:
  • I swapped the Idle Air Control Valve. I thought this resolved the issue but it hasn't. It might have improve it slightly I guess.
  • I've also swapped the Engine Coolant Sensor. This hasn't made a lot of difference either.

Does anyone else have any other ideas? It is a real pig to drive at the moment!!

Cheers
Nick

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Tue 6 Oct 2015 15:52
Ford Mondeo - Idling / Revving Issues - elekie&a/c doctor

Very little to go wrong on these.Erratic idle is usually dirty air control valve or sticking throttle butterfly or cable.Another possible is a split engine breather hose,located low down at the front of the engine,between the inlet manifold and block.Bit of a pig to access.

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Wed 7 Oct 2015 13:36
Ford Mondeo - Idling / Revving Issues - nick3young

Thanks for the response.

I don't think I've done a particularly good job of explaining my issue fully in the first post - I wouldn't particularly describe my idling as erratic... its very predictable. e.g. stop at a junction in the morning first thing - car stalls. stop at a junction when the car has warmed up - car revs to 2000 before dropping again.

It isn't random. Do you think it would be worth swapping the 'throttle position sensor' befroe I try swapping the throttle body?

I've looked at the engine and whilst it is revving up without my foot on the pedal, the cable looks like it is returning to its original position (not sticking). But obviously I can't tell what is going on with the butterfly.

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Wed 7 Oct 2015 18:42
Ford Mondeo - Idling / Revving Issues - elekie&a/c doctor

Unlikely to be either the throttle position sensor or body.Did you clean the swapped idle control motor?Is it a s/hand unit?

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Thu 8 Oct 2015 13:42
Ford Mondeo - Idling / Revving Issues - nick3young

I've purchased a throttle position sensor for what it was worth (£7). Hopefully get that in today and I'll report back... I'm not overly confident either though.

The idle control valve was brand new... but it was not a genuine Ford part. I don't know how important that is. I guess since I swapped my old one out, put the new one in... it's a bit of a coincidence that the new one has exactly the same fault? So I don't think that is to blame.

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Fri 9 Oct 2015 14:05
Ford Mondeo - Idling / Revving Issues - nick3young

Nope - throttle position sensor didn't fix it.

What would be worth replacing next?!

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