Rough Idle

[ChaosWarlord26]

Ok I know the title says it all...oh know not another one of these. I am a new member to the forum but I have been search everyone's post for about 3 weeks now trying to figure out my problem. With no luck thus far here goes the thread.

The actual symptoms are that at idle is idling really rough almost like loping. It tries to die then comes back. It will do this in Park, Reverse, nuetral, or Drive only at stop. When driving the car runs great. good acceleration. But when I come to a stop light and just let it idle it messes up. I have noticed though that when it is idling rough if I turn on the AC the rpm's change and it quits temporarily.

Ok so I am driving a 2001 Focus Se. 2.0 SOHC. I have installed a Cold Air Intake (Short Ram) on it. I have taken it apart multiple time and made sure the was no leaks. I keep getting this code from the CEL with an OBD-II reader. (PO171) I know, System Fuel to Lean Bank 1. I have had the intake on it for more than 3 months prior to it acting this way.

What I have done so far is change the fuel filter, changed the Spark Plugs, Changed the O2 Sensor before the Cat. Tried different grades of fuel and fuel treatments. I have cleaned the MAF 3 times in the last week with CRC MAF cleaner.

My next steps are checking the fuel pressure at Idle. Does anyone know what the pressure is supposed to be at idle? Also does anyone else have any thoughts of what it could be? I am thinking that it could be a bad MAF, EGR Valve, IACV, or bad fuel Pump. Any help would be greatly appreciated. Thanks

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[maggot515]

well all focuses have a kind of lopey idle theres nothing you can do about it

[ChaosWarlord26]

Anyone else have any clues?

[HyBalz]

Have you tried disconnecting the battery to reset the computer? BTW,Welcome to FF!

[mighty_mouse]

Welcome to FF.com. I have noticed the same symptom in my car, but also in many of foci that I have ridden in. So I would believe the rough idle to be normal.

Mouse

[viney266]

Welcome to FF.

You have done well, and checked or fixxed most of what I would say to look at. I would say to check the plug wires and make sure they are tight to the plugs and the coil. You can also pop the hood at night, use a spray mister and mist under the hood around all the electrical wires and plugs IN THE DARK. Watch for arcing of any kind and listen for a miss.
Also, pull the plug on the cylinder the code is for. Does it look any different than the other plugs? Let us know.

[rebelyouth]

Son i have been trying to smooth out my idle for long time now, i am thinking that just a feature of the focus zetec, i own the same year as u do also, with K&N sri.

[ChaosWarlord26]

Thanks for all the welcomes, Like I said I have been here for a while now just didn't become a member until yesterday. I find it easier and more respectful to search and dig for the solution first before posting a thread that so many people have already posted....

I have disconnected the batterymultiple time to reset it, and I have also reset the CEl by usin the OBD-II reader.

I have checked all the plug wires when I replace the plugs. As for wich cylinder the code is for I have no clue, because the OBD-II does not tell me that much detail. But thanks.

I guess my next steps are to check and clean the EGR valve and lines. Then check and clean the throttle body, and the IACV at the same time.

Now it is becoming a matter of money since all the rest of the parts that are next in line are starting to get pricey.....

Does anyone know what the fuel pressure should be at Idle? That is the next thing I am going to check.

[ChaosWarlord26]

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[ChaosWarlord26]

Not trying to bring back a dead thread but I have found the problem. After many hours of pulling off pieces, EGR, IACV, Throttle Body, etc. I got it all back together and at the end when I was getting ready to give up I heard a louder hissing noise that wasn't there before. Come to find out it was a vaccuum line. This one was made of a hard plastic in a Z-shape. It was located on the back of the intake manifold and it was the center of the 3 that connected to it. I goes from the intake mani. to the (I believe) Evap for gas fumes to return. Or something like that. I took the hose to ford and it was about 40 bucks for s new one. Just wanted to let everyone know and thanks for all the help.