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Discussion Starter #1
2000 Focus LX, ATX. Recently I've been having problems with idling. Usually I drive with A/C on and when I come up to a stop light the car is automatically idling higher because of the A/C being on. When I turn the A/C off and come to a stop the idle seems to stutter and shake a little. This has only started to happen and I want to correct the problem before it starts to stall out on me. Where should I be looking for a fix? Is the cat clogging, maf, 02 sensor???
Where would be the most likely place to look?
 

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Discussion Starter #3
Nope, all is stock. What do I look for that would be the most likely cause? Anyone?
 

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The idle should be the same AC on or off. The computer is supposed to compensate for that so the idle speed remains constant. I'm pretty sure this is all electronic. I'd suggest ypu start by checking all your wiring connections relating to the compressor, the pressure switch under the fender ahead of the RF wheel, and any others relating to the AC. (And any others, period.)
 

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Discussion Starter #6
No, actually mine is 'upping' the idle with the A/C on. The problem seems to be with the 'normal' idle with A/C selected off. It seems to be lower than normal. With the A/C on and the idle slightly higher to compensate it runs normal but with the A/C off is when it is running rough or sputtering. I'd like to adjust the regular idle up a little like in older cars but I guess you can't do that with the new cars. What can I do to get the regular idle to run higher or normal again?
 

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viney266 said:
If memory serves me right.. There is still a small idle screw on the TB, just like in the old days..adjust it a little
Nope our idle is controlled by the computer and not that little screw. Trust me it will do nothing to adjust it but cause you problems. The purpose of the screw is to keep the butterfly from completly closing all the way when your foot is off the gas.
 

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Discussion Starter #9
Come on guys, help me here....Viney, you are a moderator? Please be more correct with these kind of instructions. I don't want to go tweeking screws on the TB if lildisco is correct in saying it will screw things up. And lildisco, doesn't a screw that will adjust the butterfly valve a little exactly what I would want to adjust anyway? This would adjust idle wouldn't it?
Can anyone give me some good info on this please?
 

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The little screw on the TB only opens the butterfly a hair more to allow air in a bit better. It does not add more fuel. I have a FC 65mm TB on mine, and many of them came adjusted a hair to tight and needed to be opened a bit more to make for smooth throttle tip in.. With the stock TB this is not neccessarily the case ( my brain was thinking about the 65mm, as we get asked about these all the time). However, there is nothing you are going to damage or "screw up" by moving this screw.. Logic dictates that you can always move it back...Geez!

BTW...as moderators we do not have degrees in focusoligy, just so you know ...LOL
 

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I don't have a 65mm TB so i wouldn't know about the other stuff. I did however installed a UDP and thought with the same logic as you Vinney. I'm just going to up my Idle up a little bit(I have a system in the car). It seemed to work at the time, it did raise the throttle up a smidge. But after i restarted the car it went right back to idling the same. After a few more times to up the idle, my idle has never been quite perfect and has jumped around and even stalled. So i might have to buy a new OEM or Aftermarket TB and start over. Just my .02 so nobody does what i did.
 

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Doesn't anyone have a Ford manual who could offer something other than conjecture on these kind of problems. We get so much opinion in these threads that only take up space. I know I can/t contribute, but I have to arrow down so much to find "nothing".
 

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my car idles high when i run the ac. i asked the ford dealer about it and they told me it was because of my cams and gears.
 

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Discussion Starter #14
StreetRacerDad, everyone's Focus idles higher with the A/C selected because this is a normal compensation to the idle. The question is how do you adjust the idle a little higher when it is sputtering or idling slightly lower than normal with the A/C off? Somehow the idle must be adjustable. Ford must do it all the time with tune-ups or problems don't they? Is it adjusted at the TB, the accelerater cable connection, the computer, or where?

Also is there another place to look for the solution? Maf, spark plugs, fuel filter, etc? It only started doing this so I'm thinking that the idle adjust hasn't changed. I'm just looking for ways to correct this problem, adjusting idle, cleaning something, checking something, etc.

Anyone have this problem in the past and have corrected it? Or anyone with a complete manual with tips on this would be helpful. Thanks.
 

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You could try the basic stuff if you haven't done so already. Fuel Filter, Tune-up, Air Cleaner. Maybe you even got a bad tank or two of gas. It's really hard to say. You just don't notice it when the a/c is on because it obviously raises up your idle. It sounds like something is up ignition wise and you only notice it when the car is at normal idle. Do plugs, wires, fuel filter, air cleaner. If that doesn't work, you might have a dirty MAF and there's a how-to somewhere here on how to clean it. It could be something electronical to do with your ECU but i doubt it. Try the basic things and see what happens from there.
 

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Discussion Starter #16
Thanks lildisco, I think I'll try a tune up first. Change plugs and filters. I'm doing an oil change soon so I'll do the other stuff then. If it doesn't help I'll look into the maf I guess.
I really don't want to tweek idle screws yet since I haven't heard of a proper way to do it because of everything being control by computer, etc. I'd sure like to know how Ford does it.
 

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If you look at the Engine Emission Information label stuck to the underside of the hood it states that the ignition timing, idle mixture, and Idle speed are not adjustable.

So alright, I played around with mine a little and I found out something I never noticed before: when my compressor comes on, the idle speed does indeed change- it DROPS about 150 rpm. But the idle remains so smooth I never even noticed it before.

I don't think the tune-up stuff is it either. You would think that adding the compressor load would make any tune-up problems worse, not better. On the other hand, it's cheap and easy and you never know.

Since everyone but me seems to be in agreement that the idle speed increases when the compressor kicks in, how about a small vacuum leak that causes a lean condition, but once off dead idle, the leak becomes negligable compared with the increased airflow needed to run the engine at the higher RPM?
 

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Discussion Starter #18
Blurvfocus, I'm guessing that Ford puts the Engine emissions label under the hood once they have adjusted the idle to the set rpm and do not want lay-people (drivers) tweeking screws and messing with idle that is set to the most efficent operational condition with the computer as the car is new. But they did adjust it to rpm idle at some time. How is that done by Ford? If the car gets older and may need a little tweek what would they (Ford) do? Adjust with a computer chip, adjust the throttle cable, tweek the screw on the TB?

I agree that maybe the tune-up items may be the wrong fix but it is easy and I need the plugs and filters done anyway and I am curious if it will change the idle performance as well. I'll let you know.

As far as the vacuum leak creating a lean condition and effecting the idle, I don't think that is it because I did have a small hole in a vacuum hose that did not effect idle much but it threw the lean code (262 I think? Can't remember the exact number). In other words, a small vacuum leak creating lean condition throws my code but doesn't effect my idle very bad as the condition is now. Vacuum leak would have thrown my code long before now. It just seems like the car is getting older (100,000 miles) and needs a little boost to the idle. And like before, if Ford sets the idle when the car is brand spanking new what would they do to bump up idle a little on an old car that needs a little adjusting to run smoother?
 

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that's why new cars now adays have a gizzilion sensors. It senses what needs to be done by mulitple sensors and adjust air flow and gas accordingly.
 

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The PCM controlls the idle speed through the Idle Air Control (IAC) valve. If the engine won't maintain a stable idle speed when the power steering is activated, a substantial increase in the electrical load, or the A/C, check the IAC. If one or more loads are properly compensated, check for a sensor for the uncompensated load. Also, the shop manual states the the IAC is "NOT ADJUSTABLE and CANNOT BE CLEANED". It also states that: "The traditional idle air adjust procedure as well as throttle return screw are no longer used on OBD applications"
 
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