High revs when idling, no one knows what's wrong

[Infernal01]

Fixed:

I fixed it, the problem was that my camshaft was chipped in one of the corners. I'm guessing this happened because of the timing belt being incorrectly installed.

All the other parts (IACV, TPS, etc.) had nothing to do with my problem.

Original post:

Hello, i was sent here by Djzx3 to ask for help. The problem started about 1.5 years ago, i tried a lot of fixes since then, i'll just sum them up:

The car:
2001 Ford Focus 1.6, petrol

The problem:
- when the car is not in gear and moving, the revs stay at about ~1300 rpm, sometimes going up to ~1900 rpm
- when the car comes at a complete halt, after 2 secs, the revs go down to 900-950 rpm

What i tried:
- changed IACV 4 times (new, each time), at this time, the IACV is blocked - no air going in
- changed TPS 3 times (new, each time)
- changed the throttle body
- checked for false air intake (nothing found)
- changed some air sensor (forgot it's name, MAP or MAF)
- changed PCV valve thingy
- exhausted 3 car services and a Ford dealer, no one knows what's wrong

Other things that may be related:
- after running for a few weeks like this, the IACV goes bananas, revs going up to 3-4000 rpm, right now it's blocked by a piece of plastic
- the alternator was giving over 15.5V to the battery, i changed both with brand new ones

I would appreciate even the smallest advices, thank you.

A short (15 secs) video with the problem - at about the half of the video, i stop doing anything (except braking of course):

YouTube Video

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[elsolo]

I would start pinching of vacuum hoses looking for a vacuum leak.

[Djzx3]

15.5V seems high? Should be 14v's.

Maybe the alt is over charging, and give the TB a weird voltage reading, which translates into a weird idle?



This is why I suggested you come here and ask, people here know a real lot about all this.


Welcome, and glad to see you made it over here.

[Infernal01]

Originally Posted by elsolo

I would start pinching of vacuum hoses looking for a vacuum leak.

4 services did this, they found no leaks. it doesn't behave like a leak either, it's exactly the same every time, no fluctuation

Originally Posted by Djzx3

15.5V seems high? Should be 14v's.
Maybe the alt is over charging, and give the TB a weird voltage reading, which translates into a weird idle?
This is why I suggested you come here and ask, people here know a real lot about all this.
Welcome, and glad to see you made it over here.

thanks, it was 15.5V, now it's 14V - after i changed the alternator and battery

[Djzx3]

Bump, someone help this guy, he has been at this problem for months now, with many parts replaced, but still no resolution.

[Chris_HT]

hmm, does A/C make any difference?

and also, did you try to run 4ga cable from alternator to battery, and from battery negative to chassis, just to be absolutely sure battery is actually getting all the juice from alternator? cause if ECU detects that it needs more power than it's actually getting, it will get the revs up to compensate.

[Infernal01]

Originally Posted by Chris_HT

hmm, does A/C make any difference?

and also, did you try to run 4ga cable from alternator to battery, and from battery negative to chassis, just to be absolutely sure battery is actually getting all the juice from alternator? cause if ECU detects that it needs more power than it's actually getting, it will get the revs up to compensate.

with A/C on, the car runs normal, no revs

i will try that tomorrow, thanks

[whynotthinkwhynot]

You're wasting your time running a new cable from the alternator to the battery, as long as the battery is remaining charged (you'd know in a day) then it is working. Besides, high voltage will cause that problem, not low voltage.

There are a lot of things to check here that might not have been checked at the dealer or other shops. The throttle plate could have been adjusted wrong, or might be sticking. The throttle plate stop screw, which some people think is an idle screw, is not supposed to be adjusted. Perhaps in Romania you aren't used to stupid people who think they know everything, and do things to cars that cause problems like this because they don't know everything. I've seen plenty of stupid Americans who do, and they use screwdrivers on the throttle plate stop screws. Remove the air intake so you can see the throttle plate. Work the linkage by hand to see if it is sticking and not shutting all the way. Look closely at the springs and cable attachments to see if anything looks out of place. If you can't tell if the throttle plate is stopping where it should, then try loosening on the throttle plate stop screw, and see if the throttle plate moves backwards. There is a lip inside the throttle body that stops the throttle plate, that screw should stop the plate at the same instant as it hits that lip. To reset this you'll have to have a good sense of feeling- loosen the screw until the plate is against the seat. Then use one finger on the plate while the other hand slowly turns the stop screw back down. Set it so that the stop screw stops the throttle plate at the same instant that it touches the lip on the inside.

Of course, if you find that the cable is sticky, and holding the throttle plate open- replace the cable. You can try lube- graphite or a grease type of lube might work. I wouldn't try spray oil like WD40- that will eat up any sort of grease that is inside the cable itself.

Running without an IAC is not a fix, and the car shouldn't run like that.

Other more insane issues would include damage to the IAC wiring harness that is allowing voltage from another circuit in the same harness to get into the IAC wiring. You might have to find this one the old fashioned way of simply tracing down the wiring.

I'll try to think of some other stuff. Oh, your car does have a MAP or MAF somewhere. EFI won't work without it, but it's not the problem. Those don't control engine idle speed. Another idea might be that there is a leaking fuel injector, but I'd think you'd have codes for the O2 sensor if that was the case. Another way to check is by looking at spark plug deposits, but if you have platinum or iridium plugs, then it takes a very long time for deposits to build up.

I'll try to think of some other stuff, but for now I have to go to work.

[Infernal01]

Thanks for the interest in my problem.

I know there are a lot of bad mechanics. I actually changed the whole throttle body (i forgot to mention this) and it's working normal, when the car is reving the clapet thingy is completely shut.
And yes i have a MAP or MAF sensor (i don't remember which one) but i changed it with a new one.

The fuel injector sounds plausible, i'm getting insane consumption.

I do have one question tho:

Originally Posted by whynotthinkwhynot

Running without an IAC is not a fix, and the car shouldn't run like that.
Other more insane issues would include damage to the IAC wiring harness that is allowing voltage from another circuit in the same harness to get into the IAC wiring. You might have to find this one the old fashioned way of simply tracing down the wiring.

If my IAC is blocked and i still have problems, doesn't that mean the IAC is not the fault here ?

[Infernal01]

Just an update, i made a short video (15 secs) with the problem - at about the half of the video, i stop doing anything (except braking of course):

YouTube Video