Rough Idle / Hesitation at partial throttle while accelerating - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

FocusOnMe · 11-02-2011, 20:46

When my car is at an idle my RPMs don't stay in one place all the time. It drops below and rises above 1000RPM occasionally. While I'm not sure when this problem started, and may not even be related to this next issue, I believe I started noticing it after I noticed the hesitation. If I'm in a higher gear at a lower speed and give it anything but full to the floor throttle it will hesitate while accelerating. Kind of like a jerk every second or so. I'm not sure how else to explain it.

Anyway, I first started noticing both of these after I replaced my air intake. I went to AutoZone and they pulled my codes, resulting in two running lean codes. I told them about my intake and they said the reason it's hesitating until I hit full throttle is because I have too much air coming in and when I stomp it it dumps more fuel into the mixture which is why it evens out when I do so. I'm wondering whether these two things are related and what can be done about them. The rough idle could be one of too many things, but the explanation I got for the hesitation seems pretty air tight(!).

(I've been told to put my stock intake back on and see if the problem persists, and I've thought hard about doing it, but it took me a good hour to rig my intake together (I've got my MAF sensor pretty snug in there with silicone all around it) and I'd hate to have to do it again..)

**R.S.LOGAN** · 11-03-2011, 04:52

Make sure there is no air leaks from any vacuum hoses / pipes .

FocusOnMe · 11-03-2011, 10:47

Quote:

Originally Posted by R.S.LOGAN

Make sure there is no air leaks from any vacuum hoses / pipes .

Well there aren't any leaks in the intake pipe itself that I can hear.. I made sure everything was sealed up pretty good. All of the vacuum hoses stayed where they were to begin with. The main rubber pipe never got removed; I simply took the box off and out and ran the main pipe to an adapter for my MAF and on that is the filter.

**djzx3** · 11-07-2011, 20:46

What motor is this> The Zetec or Duratec?

You got to give some of the cars info, Year, engine, trans, liter.

But it sounds like the AIC might be worth cleaning, and maybe replacing. If you tell me which motor you got, I can tell you where to locate it.

**R.S.LOGAN** · 11-08-2011, 00:25

'08 Ford Focus S Manual

**R.S.LOGAN** · 11-08-2011, 12:06

If there are no sign of air leaks (I've got my MAF sensor pretty snug in there with silicone all around it) and I'd hate to have to do it again..) you might have to undo your work and try cleaning MAF sensor .