SirMalc

Mk1 low idle speed issue

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Hi all,

 

I own a 2004 Ford Focus Mk1 that has a low idle speed issue. When the engine is fully up to temperature and I let off the throttle, the revs will fall back down too low, causing the car to judder before the car sorts itself out and finds the correct 750RPM idle. This issue is much more pronounced under a heavy electrical load (air-con/headlights etc.) with the air-con managing to sometimes stall the car completely.

 

I have recently changed: Air Filter, Oil/filter, Idle speed control valve, alternator, cleaned the throttle body plate, spark plugs, fuel filter. None of which has fixed the issue.

 

Another issue of note is that the engine can be heard 'pinking' when accelerating under load (high gear, low revs) uphill. Not sure if this could be related to my idle issue, such as the fuel being too lean or the car can't figure out the correct air/fuel mix.

 

After a lot of googling I came across this thread from 2009: https://forums.overclockers.co.uk/threads/ford-focus-idle-problem-plus-others.17960952/ . I'm not taking it as gospel, but I did wonder if my car also needed this ECU/PCM update, especially as my car is not throwing up any error codes and is from the same year.

 

I took it to Think Ford in Guildford near me who said they cannot find any vacuum leaks on the engine at all, so I've asked them to see if they can update the ECU but I'm phoning on Monday to see if they managed to update it. One of the mechanics there beforehand did express concern that being a 14 year old Ford, they may not be able to update it due to it being incompatible with the software or that updates are no longer available. But I presume being an official manufacture garage they should still be able to access software updates for old vehicles of theirs surely?

 

I can't imagine these cars rolled off the production line like this, so there must be something that needs fixing. Has anyone here experienced similar issues or have any suggestions as to what could be causing this issue?

 

Many thanks,

Malcolm.

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What is the idle like when the engine is up to temperature and you disconnect the the plug to the idle control valve?

ie Base idle.

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30 minutes ago, Dave Kelly said:

What is the idle like when the engine is up to temperature and you disconnect the the plug to the idle control valve?

ie Base idle.

That’s something I’ve read about and I will try when I get the car back from the garage. I presume the car will compensate by opening the throttle body plate?

 

i cleaned the original ICV with carb cleaner which didn’t help, then proceeded to replace it with an aftermarket ICV. Neither fixed the issue. Potentially the aftermarket one could also be duff, but I doubt it.

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If the valve is operating correctly, the ECU will then hold the RPM at tick-over 100rpm to 150rpm above base once reconnected.

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7 minutes ago, Dave Kelly said:

If the valve is operating correctly, the ECU will then hold the RPM at tick-over 100rpm to 150rpm above base once reconnected.

What happens to the RPM when the valve is disconnected? Or do you mean it will hold +100rpm until the valve is reconnected?

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When you disconnect the electrical plug connector, the idle should be at 750rpm. (Base Idle)

Once you connect the electrical plug, the ECU should take over and raIse the RPM accordingly. (to 850-900 rpm)

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With regards to your other issue, "Pinking" otherwise known as pre ignition, this could be due to a number of things.

When did you last change your plugs? 

Also, what sort of mileage has the car done?

 

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1 hour ago, Dave Kelly said:

With regards to your other issue, "Pinking" otherwise known as pre ignition, this could be due to a number of things.

When did you last change your plugs? 

Also, what sort of mileage has the car done?

 

I changed the spark plugs 3 weeks ago with new Bosch ones. Coil pack hasn’t been changed but I think there’d be bigger issues if that was failing.

 

Car mileage is about 80k. 

 

I did did wonder if one of the fuel injectors may be dodgy. I could try using some additive in with the next fuel load, or maybe try a higher quality fuel as I normally get standard supermarket petrol.

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I believe that you can do a resistance check on the injectors so as to eliminate them, not sure of the correct value though.

If you can test all 4 and they are the same, then at least we can eliminate them.

Do you know if the timing is controlled by the ECU in conjunction with a crank angle sensor?

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