Shaking while stopped. Especially below 40 degrees

[Eastmeadow1472]

I'm have a issue with my 2001 Expedition. When I am at a full stop after a minute the car begins to rev on its own and the rpm dip up and down from 0 to 1,000 and the light dim a bit. When I step on be gas it hesitates and then goes. But when it's warm out there isn't much of a issue. The car runs fine otherwise.

Is it the following:

1. Gas Pump going
2. Need a new gas filter
3. O2 sensor
4. Timing belt

Any help would be great.

 

[Bedrck47]

Part of your questions are #1 and #2 I would say that since you are asking if its fuel related that you have no idea how old the fuel pump is or when the filter was last changed I would start by checking the Fuel Pressure at the fuel rail when you get that figure Post it and we can go from there.

#3 if you were having a problem with the O2 sensors I would think the you would be getting a Service Engine Light

# 4 You don't have timing belts But you do have timing chains.

You may want to check the maf sensor Check for any vacuum leaks ETC.

Also what engine does the expy have??

 

[docraymund]

You should check your idle control valve.

 

[1997SCEBFEX]

++ on IAC.

 

[razrback]

I've had the same problem on 2003 4.6. I've replaced both upstream sensors, IAC, MAF, every vacuum hose that looked suspect, fuel filter, gas cap over a couple of years. The problem is mostly gone, but at times it will cycle mildly. I wish I could tell which one corrected it, but I can't. I can say that the IAC, MAF, and O2 sensors did not make any difference on mine.

 

[1955moose]

As bedeck 47 stated, please do the fuel pressure test. You should have about 35 psi off, and 35-45psi running. If you do, in most cases you can eliminate the pump, filter, and fuel regulator. Second get a Dtc code diagnostic. Usually free from most parts/repair shops these days. As we've stated before, don't start changing parts, all Willy nilly. It's frustrating and expensive. Your idle air control motor will generally act up hot or cold. But it is a serviceable item, that can be decarboned, and reused. Usually the revving up and down is a sign of a intake leak, and lean run condition. You might want to spray down all the hoses, and gaskets involving your intake path. It will smooth out when you find the leak. The pcv valve hose is a suspect.Let us know what you find, and the fuel readings.


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