I decided today i wanted to get to the bottom of my high idle. Wen i unplug the IAC my idle drops to normal. This leads me to believe the iac is working properly and somewhere is asking the motor to rev higher. Mayb something is clogged so that adfitional air not getting into engine. Maybe a leak? Theres no codes ive looked for leaks. It revs lil over 1000 rpms when its warm. In drive it drops a lil under 1000.

any thoughts? Figure i jus start replacing things. Start with MAF?

 

I’d recommend first disconnecting the battery. Then pull the IAC and using an aerosol spray cleaner that’s IAC Safe, clean out the valve. While you have it off, using an aerosol throttle body cleaner spray out the throttle body around the throttle blades and through the IAC opening on the intake. Reinstall the IAC and reconnect the battery. When you start up the truck it will have reset the computer so it will have to go back through the learning mode. Let it idle till its warmed up. Then drive it around through normal traffic.

If your still experiencing any problems try cleaning the MAF sensor, ensuring the aerosol cleaner is MAF Safe.

 

I have actuallyy cleaned both very thoroughly. As well as the egr valve. New tps as well nothing changed with idle.

 

i just through in a new MAF-it didnt help me. i guess the next thing to do is say f it or look into the EGR and gas fumes return lines.

 

Kris,

Did you try disconnecting the battery long enough to clear the PCM memory?

A few other things to check would be the throttle cable (any binding or sticking). Try pushing the throttle closed manually (by hand). Have you check for vacuum leaks?

 

all parts cleaned since i did a head replacement. checked the throttle screw. the throttle cable seems loose so i dont think its sticking. ive sprayed hoses and areas i think that might be leaking wd40 and throttle body cleaner and got no results. only things i can think of next is EGR valve, or EGR solenoid, or canister purge valve or lastly the tach is just not reading the number accurately.

 

If it is doing it when you first start the truck it is normal. Winter time it does this till the truck is at normal op temp, then it will drop to normal rpm.

 

it stays highs after being warm, even after 50mile trip.

 

I'm not sure if you have one or two coolant temperature sensors. It should be two , one for the gage and one for the PCM. If the PCM doesn't see the engine up to operating temp , it will raise the idle.

 

Ya i dont think its the tach because i seen it drop to normal wen i unplug the IAC. i believe obe coolant sensor by the thermostat. Is there a way to test this theory?

I mean it does drop lower like it should once its warm. When its cold maybe 1400 once i start it n it drops to 1000 wen it warms up. In drivr itll drop to 800 sometimes.

 

If there was a leak it would still rev up when i disconnect the IAC instead of dropping. So tje computer has to be telling it that it needs more air? Right?

 

Kris,

A few other things that could possibly cause a high idle problem:

Throttle position sensor out of adjustment or defective
Power steering pressure switch stuck closed
AC demand signal to PCM

 

The TPS is new so ima rule that out. If i were to check those other two how could i do it?

 

Ok so new egr tube and pcv grommet and i see a slight improvement. In park it sit jus below the 1 line on the tach. Think it was that grommet the new one was sign tighter. The guys at monaco ford said egr would make it stall if it was bad so i kept the old one. Thanks for all you help guys and this wRm weather were havin in CT. Nxt project will be leaf springs n shackles and torsion bars and lastly 1.7 rockers.

 

Looking through the ETM for 2001 model I don’t see a listing for the power steering pressure switch on the 3.0 or 4.0 engines. Only on the 2.3 & 2.5. If there is one on the 1999 model, it will be inline with the high pressure line between the pump and rack.

When you turn the AC on you should notice the RPM pick up slightly.

Did you try replacing the PCV valve?

 

i think i broke my a/c beacuse when i was trying to disconnect it from the cyl. i disconnected a pressure hose and lime green juice came out, not antifreeze but freon? or refrigerent. well i havent heard it kick on lately when i go to turn it on so im assuming i need to recharge it first. (it was the metal tube i diconnected from the air conditioner pump

and the pcv is new. with in the last month.

 

Rockauto lists the switch.For the power steering.
http://www.rockauto.com/catalog/moreinfo.php?pk=933244

 

oh its not too expensive. maybe just replace it for the hell of it. not quite sure where its located on mine. is it around the pump area?

 

Try setting the selector control to the off position and see what happens to the idle speed. I believe it sends AC Demand signal to the PCM in all modes but off and dash vent only.

I thought I saw one on my 2001 too. I know if I rack the steering one way or the other the RPM does pick up.

 

so if i wanted to test the steering theory. can i just turn my wheel and see if it affects the RPM's?

and the a/c control switch to off, cuz usually its always off cuz i never use it.

 

Yes if you rack the steering one way or the other you should initially notice the RPM starts to drop. However, when the the pressure switch closes it should raise the RPM to compensate.

If you follow the high pressure line from the power steering pump down to the rack you should see this switch if its there. If its stuck closed simply unplugging it should lower the RPM.

As for the AC you may still see the RPM rise when you have the selector in any position other than the off or dash vent position even though the system is discharged. Just make sure its in the off position to check.

 

ill deff be looking into the steering switch. so once i find the switch following the hose, just unplug it and see if it drops and if it drops then its no good, correct?

to be sure. its the rubber hose that leaves the resevoir down to the rack? correct?

 

Correct, as long as the wheels are straight ahead.

 

perfect. ill check it out first thing tomoro. see what i can find. ill let you know how it goes. thanks a ton you been very helpful!

 

Did some tests today. Got a misfire, egr code and iac malfunction. I replaced the iac and fixed the egr. But still idling like 1100. I tried steering wheel when i turn it the rpm goes down but then but bak wen i stop turning it.

Could it be the air temperature, or the rubber hose to the pvc?