Ford Focus ST170 2003 - Power loss at high rpm

Honest John Back Room » Technical matters
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Fri 8 Oct 2010 23:47
Ford Focus ST170 2003 - Power loss at high rpm - Jim Bob

I have an ongoing problem with my ST70 (over a year). The car behaved fine up until this point (I've owned it for 6 years).

The problems and history -

Initial fault problems:

· stuttering /loss of power on medium – long cornering (e.g roundabouts)and when going uphill

· power loss at around 3000-3500 rpm. Increased application of accelerator at this point made this worse.

· problems worse with less fuel in tank but still occurred frequently

New coil pack 15/7/09. Failed to make any difference. Car broke down following this.

New pump and sender 17/7/09. Was better after the new pump but never has been 100% OK.

Continued problems:

· misfire / stuttering power loss at around 4500-5000 rpm.

· with full tank (& cold engine?) problem occasional. Once down to half tank or less – power loss frequent at 4500 rpm

New spark plugs, and fuel filter with service 13/5/10. –no change

New IMRC (inlet manifold runner control) 28/9/10 after engine management light came on and checked by Ford dealer. – no change

Other forum threads with similar problems ahve suggested MAF sensor - but this doesn't seem to have worked for those people.

Can anyone offer any ideas please. I'm at my wits end and just about ready to trade-in...

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Sat 9 Oct 2010 02:35
Ford Focus ST170 2003 - Power loss at high rpm - jonlad1974

hi unplug the air mass sensor and see how it runs for a day or two then plug it bk in as i had a golf 18 turbo petrol that would do the same thing i unplugged the air mass sensor and it was fine then i plugged it bk in after a day and it would run fine for a week or two then i replaced it

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Sat 9 Oct 2010 17:00
Ford Focus ST170 2003 - Power loss at high rpm - Jim Bob

thanks for the info Jonlad. I have unplugged it and will report back in a few days....

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Sat 16 Oct 2010 02:22
Ford Focus ST170 2003 - Power loss at high rpm - Jim Bob

I unplugged the MAF sensor. Unfortuantely the problems have persisted and the car just ran even worse. Thanks for the advice anyway.

Can anyone else help?

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Sat 16 Oct 2010 11:17
Ford Focus ST170 2003 - Power loss at high rpm - Collos25

You answered the problem yourself as you said its worse with a low tank shouldn't that tell you where to look ie the high pressure fuel pump.

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Sat 27 Nov 2010 18:39
Ford Focus ST170 2003 - Power loss at high rpm - Jim Bob

Ta Andy,

Had written to dealer to see what inexpensive diagnostics they could offer. Ended up going for test drive with chief mechanic and then booking for further tests. They removed the tank, filter etc and found significant contamination (from dirty fuel I guess).

Replaced filter and sender unit (for 2nd time in 18months) and cleaned tank. - Problem solved. Its been fine for 2 weeks and counting.

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Sat 27 Nov 2010 19:04
Ford Focus ST170 2003 - Power loss at high rpm - Collos25

Its great when you find the problem and everything is ok again.

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