Genuine all the time - don't buy so-called performance parts or cheap
alternatives. I did that with one car to save money and it cost more as the
parts didn't last as long and they were nowhere near as good. It's often
cheaper to go to the main dealer!
Certainly for bulbs, wipers, oil, filters and other bits.
I've already tried here and on the Focus group but the fault is a bit of a
The most obvious/irritating fault is intermittant rough/varing speed at
idle. The revs go up/down/up/down rhythmically, sometimes it feels like it
will cut out. Sometimes it idles quite well, but leave it for a few seconds
and it usually starts acting up. An ECU reset (disconnecting the battery for
half an hour) seems to help until it relearns.
There's another fault where when idling, if the revs are increased up to
around 2100rpm they fail to increase with further throttle opening, causing
pronounced hunting (like the idle fault), until the throttle reaches a spot
(quite a bit more open) where the revs suddenly pick up as normal.
The voltage output from the TPS seems to increase smoothly while the fault
There's no fault codes in the ECU, there are no vacuum leaks (confirmed by
me and mechanic) and the PCV valve and IACV have been replaced. (The old PCV
valve was stuck open causing poor idle, the revs to stay high and stalling
when dipping the clutch.) The air filter is clean and the car is fairly
normal on the road, if a little twitchy at low speed. I have given it a dose
of injector cleaner. The throttle body has been removed and checked. It is
quite clean inside and it is a good seal when closed.
I've noticed the exhaust stinks of raw fuel when first started, but I
thought that might be just the ECU richening the mixture for the very cold
weather we've had lately! Fuel economy seems quite poor, but I have a habit
of running the air con a lot.
I'm at a loss, I've seen plenty of idle faults, but the throttle issue is a
bit of a strange one.
Hmmm tricky one...
Has your car had a) the modded CHT wiring loom, and b) a new CHT? If not,
change them. If the leads are at all leaky and the old CHT loom in place the
ECU often picks up some stray HT which causes breif shutdowns at worst and
at best, strange running problems.
Next check the Clutch and Brake switches are working properly (both on the
pedals) though an open or short circuit would normally be displayed in the
fault codes. A fault with either will cause erratic low speed and idle speed
issues. (though usually rpm hang not sway or stall)
Does yours have EGR? If so, check its not sticking open (not able to close
completely at idle, when it should be) which will cause exactly your
Also check the brake servo isnt punctured and letting in way too much air.
(clamp or plug the hose to test)
Otherwise get it straight onto live data display and look at adaption
levels- this should show pretty much straight away where the problem lies.
(well to an experienced mechanic) I would very carefully check the output
quality and switching of the o2 sensor, as on the EEC5 system - it adapts
very closely to o2 sensor output (rather than fixed maps) especially at low
speed, and at WOT.
Are you the same Tim who helped me out before (last summer)? If so, thanks-
it was the PCV valve which was one of your suggestions. :-)
Pass. Certainly not while it's been in the family (since around 8 months old
IIRC) I tried shoving it out of the way of the HT leads but there's limited
amount of wire to do so.
Will do. I'll get the dealer to check them out. Is there an easy way to spot
the modded loom?
Apparently this is the non-EGR model. It's the Zetec-S silvertop with MAP
sensor rather than MAF as well if that makes a difference. The MAP sensor
was one of the things I suspected. It seems almost everyone else has the MAF
version which makes getting web help a bit more difficult!
Is this a dealer job or would an independent outfit have this kit/skills?
Thanks for your help, Tim.
Umm possibly, cant remember, i deal with that many cars!!
Moving and cable-tying the CHT wiring away from the HT leads is a good
start. Does it help at all? If so, then definately replace the HT leads
before the ECU gets goosed.
Ah, you have a rare one. As I remember the MAP sensor is mounted directly on
the inlet manifold? (well it is on the Fiesta) If so it would be worth
removing it and cleaning it. Use some brake cleaner sprayed *across* the
orifice, shake it around, drain, repeat. Leave it 10mins to dry after. If
not, then *very* carefully inspect the hose that links the two for a split
that is opening as the engine moves.
An independant is likely to be able to do it- its not rocket science! A
dealer would likely look at you abit funny... In the case of a dodgy MAP,
you would be able to see straight away too low an output from it just as the
idle starts to get jumpy.
I'll try that, a nice cheap test!
Correct, behind the alternator on the left side of the manifold (looking
from front of car). I hope I don't have to change it because I don't know
how to remove the auxiliary belt to get the alternator off! I've removed
plenty of belts and alternators in the past, but I don't know about this
Aaah! This should be fun!
Links the two? I don't get it?
Fair enough, I'll ask around. Hopefully there'll be a Focus guru in my area
who'll look at it. (Sunderland / Co Durham).
Thanks again, Tim.
What solved this problem you guys discussing here because i also have same
prblem. Only difference is that mine is black top Zetec-SE engine on 2003
I changed the plugs but didn't cured it. I also have checked my plug cable
resistance which were same for everyone. I also cleaned the MAF sensor
located near the airfilter box.
Recently I add the STP fuel system cleaner. Which have Improved 5%. But
sometimes it doesn't feel like it.
Sometimes car by itself become okay and very reponsive even when A/C is
working. and then back to same problem. This happen with in a day. like the
car have moods.
most petrol fords have the same faults: plugs, leads, coil pack and in your
case I would first look at the catalytic converter, it has probably broken
up inside, this allows the broken part to fall sideways into the exit from
the box which blocks it, till it moves a bit and unblocks (if you are lucky)
Removing the exhaust section behind the cat. and looking inside you can
usually see if the cat material is loose and movable. The material is in
two halves to start with, it is usually the back bit which becomes loose. I
have often removed the cat. cut a hole in the side, removed the loose bit
of material and welded the hole shut for several years more use.
Both Zetec E and SE engines need to have the plugs *and* HT leads
replaced with genuine Ford ones every 40,miles.
Measuring the resistance will not always show up a faulty lead,
especially as your fault is intermittent.