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rough idle

msilver

Well-Known Member
Joined
December 10, 2009
Messages
112
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City, State
St. Joseph Il. Carbondale Il.
Year, Model & Trim Level
94 XLT
About a year ago my mom went to the dealership looking for a car for a car for my sister and ended up trading in our mini van for an 04 mountaineer. She bought the car knowing it had a rough idle and was told by the dealer that they would fix it. She bought the car. When she brought the car home it appeared that the rough idle was the only problem it was schuduled to go to the dealership to get the next week. It went and they said that there was no miss fire. the problem clear wasn't a miss fire i could have told her that before she took it there. long story short the dealership isn't going to fix anything. it starts up and drives fine, the problem is if you pull up to a stop sign or are parked and at idle it idles rough, the car shakes a little, the rpms dance around. it comes and goes but most the time is there.
anyone else have a problem like this?
any common problems that could cause this?
i would start working on it and change spark plugs and wire, clean the MAF but my mom gets mad if she spends money and it doesn't fix the problem

i almost for got it has the 4.0 SOHC automatic trans
 



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Idle Air Control Valve? Just a shot in the dark.. mine did the same thing when that went bad.
 






good idea i know some of a few fords that have problems with the IAC
 






This worked on my brothers ford tempo. We cleaned the IAC with carb/choke cleaner and tapped on it with a screw driver. Worth a shot. I dont know how the new sensors are.
 






About a year ago my mom went to the dealership looking for a car for a car for my sister and ended up trading in our mini van for an 04 mountaineer. She bought the car knowing it had a rough idle and was told by the dealer that they would fix it. She bought the car. When she brought the car home it appeared that the rough idle was the only problem it was schuduled to go to the dealership to get the next week. It went and they said that there was no miss fire. the problem clear wasn't a miss fire i could have told her that before she took it there. long story short the dealership isn't going to fix anything. it starts up and drives fine, the problem is if you pull up to a stop sign or are parked and at idle it idles rough, the car shakes a little, the rpms dance around. it comes and goes but most the time is there.
anyone else have a problem like this?
any common problems that could cause this?
i would start working on it and change spark plugs and wire, clean the MAF but my mom gets mad if she spends money and it doesn't fix the problem

i almost for got it has the 4.0 SOHC automatic trans

Did you ever find the fix? My bet is on bad crankshaft pulley/balancer.
 






Did you ever find the fix? My bet is on bad crankshaft pulley/balancer.

Swetrid question for you,

Do you think a new aftermarket harmonic balancer would cause this problem,
I have 03 truck and just put in 10 engine with 2000 miles out of a ranger, when company shipped engine it was resting on the exciter ring and bent pully. so I ordered a new harmonic balancer. there are no vaccum leaks, intake o-rings no leaks, I sprayed starting fluid around injectors and manifold; no change in Idle, cleaned idle air control valve and mass air flow.
I am going to replace the tps and see what happens, runs perfect for the first minute or so then idle acts up, and if i try to feather the gas to get rpms to 900 it will almost stall.

oh also check engine light code PO102 ( mass air flow sensor, intake leak, vaccum leak)

thanks
 






update, changed the tps, no luck, sprayed another can of starting fluid around intake and vaccum line, no leaks detected.

looked at the harmonic balancer at low rpm definitely wobbles. (and that is bran new)

Just for for kicks I bought a new Mass Air Flow Sensor. That fixed the Idle Problem. The Truck idles perfect now!

autozone $122.00 FYI bring the old sensor down to the parts store, there is a core charge of $87.00 bucks.

Reguards
 






Autozones's mass air flow sensor did not set the computers correct timing loss of power, and I tried four sensors from autozone all no good,

the factory ford mass air flow fixed the problem, the tech even said if i buy the part from ford dealer that there will be no charge for the diagnosis (he even put 10 updates in the computer) or labor putting the mass air flow sensor on, Great deal in my book I went nuts for two months trying to figure this out.
 






Definitely the first thing you should try is to clean the throttle body, that's usually the cause. I just noticed this thread was started over a year ago
 






Dealer did charge for diagnosis $95.00 and mass air flow sensor 220.00, bigger bill than I thought 315.00 plus tax. and problem still there, full throttle is going to 17 degrees after tdc and loss of power, all the ford techs were stumped and the the best they can do is send ford corporate an email for advice. great service gotta love it. :thumbdwn:
 






problem sloved

2003 explorer spark plug (shorter) compared to 2010 ranger spark plug (longer)

picture.php?albumid=19882&pictureid=77005.jpg


My engine donor was from a 2010 ranger with the longer spark plugs. I installed a new set of spark plugs for a 2003 explorer which are shorter. I never noticed the difference in length. I Installed the orginal 2010 spark plugs and studdering went away, I put on 20 miles and all seems good
 












Some serious detective work there. Nice going.
 






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