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Surges in 110 F Temperature

08-11-2014, 12:41 AM
well last year after 45 miles in the heat it surges if the temp is above or at 110 degress any thoughts 2001 Explorer sport trac with Early 2000yr engine series stock

08-11-2014, 07:46 AM
Does your truck have the 4.0L SOHC engine? I don't recall what year the V8 was first available in the Sport Trac.

What do you mean by "surges?" Does the engine speed increase and decrease at idle but run fine otherwise? How low and high does the idle go?

Does the surge ever go away once it starts if you continue to drive?

Do you have a fuel pressure gauge and/or vacuum gauge that you can use to monitor each/either at idle when the surge is happening?

When is the last time you had the spark plugs and spark plug wires replaced?

Did this start shortly after some service was performed (such as checking the air filter during an oil change)?

Any other details that might be pertinent? The more details you can provide, the quicker folks here might be able to offer suggestions that will get the truck running right.


08-12-2014, 12:34 AM
Well it V6 the v8 wasn't avalible until 2gen Late 2005
the surge no increase in rpm just running fine then like i pressed on the gas harder
I release throttle to about 10% fine any high surge, idles fine
turn off turn on problem, turn off unplug MAF Runs fine IDK what that means but i was think Bad MAF but that would show at other temps i think.
But at any lower temp fine
sometimes P0171 & P0174 meaning too lean checked intake vaccum fine airfilter clamps fine
i do all services my self nothing unusual

08-12-2014, 07:48 AM
Since unplugging the MAF seems to help the engine run fine, that suggests you have a vacuum leak or some means of unmetered air getting in to the intake after the MAF sensor. the P0171 and P0174 codes further support that. You need to really search the truck for vacuum issues. Don't forget to check the accordion folds of the intake air tube, the intake manifold gaskets, PCV elbow, hoses to the DPFE, an EGR valve that is not able to fully close, etc.


08-12-2014, 05:22 PM
I just thought of something else i have been getting a build up of slugs on my throttle body well i well go through vaccum lines and see.
the pvc elbow that small piece that splits off into the intake was cracked last year thats what i thought the problem was replace it and pvc valve, and if it was a vacuum leak wouldn't it effect it all the time

08-12-2014, 09:54 PM
Not necessarily. Materials expand and contract depending on temperature. You might have a situation where your PCV elbow expands when hot and creates a larger vacuum leak. Not horribly likely, but possible and worth considering.


08-12-2014, 10:12 PM
well i going to have to wait till next summer to test it, it cooling here i sorta hope something else pops up that points me in a drection

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