idle is acting up

[aircargoo]

hello all....ok. i start truck...idles fine. half way to work or less if i check my idle its high...above the 1 mark...1100 rpm on gauge. ok...if i turn truck off and restart...its back to normal where its suppose to be. is this the idle control valve people. truck has 171000 miles. runs excellent till this. ive never changed icv on this truck since ive owned it....maybe 7 yrs....

gonna check for codes right now after reading another post........lol.

txs in advance for advice and help

 

[aircargoo]

ok...i got a misfire on cylinder 3....can idle go up to compensate for misfire??

 

[1955moose]

It can. What year and engine do you have? What was the code. You sound like you've got a possible vacuum leak, and when warm your computer and sensors are compensating for the leak. As I usually post, have your engine smoke tested for any intake, or Exaust leaks. From the section you posted in, I'm assuming you have a 1997-2002 expedition. A common problem also is check to be sure your spark plugs are torqued to 14-15 foot pounds, they do come loose. Don't over tighten plugs. If you do have a intake leak, replace pcv hose, they are famous for leaks. Lastly you can take apart your idle air control valve, and clean out any carbon. That and spray out your throttle body, and check for full closure. Keep us posted as to your results.


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[aircargoo]

...not changing plugs. they have what 10,11000 miles. everything was changed back then. NOW THOU....after disconnect and eye balling the coil pack on passenger side truck idles fine. this morning when i started truck idle was high with misfire code. i cleared code vdrove to shop THIS morning and thats when we eyeballed wired and coil on pass side.....since then nothing,runs fine. idles just under the 1000 mark...2 lines below.

lets see later and sunday...im home and gonna look at my wires GOOD. im thinking coil packs are good for only 10,000 miles or so....msd i have. 97 1st gen 4.6 expedition code was misfire cyl 3

 

[1955moose]

Actually coils last much longer, especially the Ford ones. The reason I was suggesting torquing your plugs, was not to replace,but to check if any have come loose. As far as the wires to the plugs, always use a dab of dieelectric grease on both ends, one that goes to coil, and to spark plug. The wires to plugs can be tested with an ohmmeter but if more than 100k miles, better to replace. Your first year edition should have only 2 coil packs one for each bank of four cylinders. On the number 3 misfire, check the connector to that injector, make sure clean, and wires have power. After that carefully put bare hand on Exaust manifold when cool to warm on #3 cylinder to see if injector is clean and firing. Don't need to tell you, not when Exaust is hot!You might also check or replace number 3 spark plug. If you do pull it, disable spark, and do a compression test of that one bank, just to be sure your problem is not engine compression related. Sounds like your getting closer, keep in touch.


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[aircargoo]

misfire code not coming up now at all......i just get the high idle. ive drove a good 40 miles this morning. almost did plugs,had them in my hands but you know what. im not changing. i got my code reader hooked up to car....going to drive more sunday. lets see.

thing is...during week....i felt the slight small stumble in engine when idling at a light with the HIGH IDLE....which at that point makes me think i have a bad something on cylinder 3 cause why did code come up? i feel it at 65-75 going up hill steady the "slight" stumble in the motor...its there sometimes.but that wouldnt cause idle to stay up. truck runs great..theres NO CODES

this truck runs 40 miles a day 4 days a week 38 highway....seems like idle or iac stuck on that highway 1900 rpm at times. 20 mile up,13 hrs later 20 miles back...its all truck does

 

[1955moose]

Could be that injector on #3, try flipping the spark wire from 2 to 3 see if code moves.


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[UtilityCow]

I've had both problems.
My truck had this random high idle issue. It would idle over 1k and felt like I had to use more brake pedal to hold it. I figured out that it was the IACV by literally whacking it hard with the tip of a huge screwdriver. As soon as I whacked it the RPM would drop. Replaced and problem went away. I think cleaning them is pointless. The Motorcraft is cheap on Amazon.
Bad IACV never caused a misfire for me. You may have two separate issues. I've had many coils go out and sometimes the bad coil caused intermittent misfires. I noticed that the misfire increased at higher engine loads like low RPM, heavy throttle, high gear. I tried to force the misfire to get the ECM to throw a code so I knew which coil to replace.

 

[1955moose]

Utility Cow, he has the first year that only used two coils, instead of eight. If his failed he would lose 4 cylinders. Cleaning the carbon out properly does work if that's all the problem.


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[aircargoo]

ok.....FOUND PROBLEM...i think!! i have that cold air intake airflow by k&n. anyway,taking it off i noticed around throttle body the big radiator clamp was loose not pushed in all the way. i took it completley off,cleaned throttle body plate which was kinda dirty (backside)..be carefull not to get rag caught on screws...without taking it off. then started it and sprayed carb cleaner in there 3-4 times at real high idle revs...put everything back together "TIGHT" THIS TIME..all the clamps.

nothing....truck runs at low rpms...sweetly. was air intake maybe all loose by throttle body i hope. i put another 40 miles with abd reader and no codes.

what im waiting on is the MISFIRE on cyl. 3.....i did get code..

meanwhile....ill keep abd code reader on truck and hope high idle is gone....

1955moose....yes first gen expy....love it...its plain and simple. msd coilpack are 70 a piece...plus,my plugs are MUCH easier to change then the c.o.p and plugs

keep you posted tues or thurs......txs guys