High Idle Blues 1994 4.0 | Page 2 | Ford Explorer Forums - Serious Explorations

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High Idle Blues 1994 4.0

Bought a fuel pressure guage today and my fuel pessure is textbook--so the regulator is not my problem--i ran codes again, there is a stored code
117 ECT sensor circuit grounded

and the same two engine running codes
411 Cannot control RPM during KOER low RPM check

412 Cannot control RPM during KOER high RPM check

Any suggestions??? I would almost have to think vacuum leak???? But as i said, i thouroughly checked but must be missing something????

this is really starting to bug me!!!! and by the way--the ect sensor was the first thing I replaced--not sure why I am showing a stored code for it--:(
 



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ECT grounded

The PCM is reporting that it is unable to utilize the engine coolant temperature. When there is no valid ECT reading available the PCM probably reverts to a rich mixture. I believe the ECT sensor test is performed on every drive cycle but you may want to clear it and drive again to see if it returns. If so, then either your new sensor is shorted or the wire between it and the PCM is shorted to ground.

Air flows from the main intake tube, thru the smaller hose to the valve cover into the crankcase. Crankcase fumes are vented thru a screen into a tube going to the PCV valve. Fumes come out of the PCV valve into a hose that connects to the intake manifold to be burned. The check valve (ball) in the PCV valve prevents air flow in the opposite direction. Inspect all of the hoses connecting to the PCV valve for cracks or breaks. Make sure they all have a tight fit connection.

The PCM is also reporting that it is unable to adequately control the engine speed via the IAC valve. You stated that the idle drops to 600 rpm with the IAC valve disconnected. I believe that's about 100 rpm higher than the stock setting. Do you have any slack in the throttle cable? I suggest adjusting the closed throttle adjusting screw to achieve 500 rpm with the IAC valve disconnected and the engine warm.
 






great explanations of the codes--thank you--i did clear them and took the truck out again to see if i could get another code--no stored code this time--still getting the 411 and 412 codes---another thing i havent mentioned before is when coasting in gear the truck bucks -- most noticeable in the higher gears?? almost feels like the iac is opening and closing??? Is there a way to trick the ect sensor?? because my high idle seems to be a little worse the colder it gets---all the pcv and vacuum lines are tight and in good shape--i tried the propane torch again today and even resorted to getting the garden hose out and spraying alot of water around the intake-brake booster--vacuum tree but it never affected the idle. I backed the throttle stop screw all the way out and idle is a very close to 500 rpm with the iac unplugged. This really has me stumped--i think i am going to make a gasket for the iac and try drilling two small air holes through the gasket to restrict the iac air??
 






just a short update--i made the gasket for the iac and drilled two small holes--but i think this is not going to work because of cold idle issues--it gets pretty cold here in PA and when I tried completely blocking the iac in the past, my cold idle made this not acceptable. idling right now with the homemade gasket around 700 rpm
 






Reality Check

I hope this long thread helps others out in the future-We know my electrical system and sensors are all replaced and the fuel pressure checked out OK as did my check for vacuum leaks--started truck this morning and cold idle is unacceptable with the gasket I put into the IAC to restrict flow--but i did notice a lot of white smoke out of the tailpipe until truck warmed up!!! I also can see that it looks like someone replaced the manifold gaskets at some point because you see a little green gasket material between upper and lower intakes??? I dont really notice any appreciable loss of antifreeze but I have been playing with sensors and thermostats so much that I havent kept a real good track of coolant--i had to add a little yesterday to the overflow but my hose above the thermostat was leaking a little and I replaced the clamp--

Could I have internal intake manifold gaskets leaking?? Anybody know a quick test for this?? I will pull all the plugs and check compression but i really dont think head gasket---Anybody got suggestions on replacement gaskets?? any brand better than others---i wont be happy until i fix this issue so looks like i am going to plan on pulling the intakes over new year holiday
 






hey guys--i may have been gone--but not forgotten--my fuel pressure is right on the money and the pressure regulator is working to spec----I made a gasket for the IAC valve and drilled two small hole through the gasket---my cold idle is low (around 500 rpm) so I try and let it idle for a minute or so with my foot on the gas pedal when cold and keep it around 1000 rpm. As soon as i start driving the idle slowly climbs to around 750 rpm when warm--this is acceptable but I still want to find the problem--i am not giving up yet--bit its too freakin cold outside to work on so this will have to be acceptble for now--when i do figure it out , i will post---but i am convinced that it is electrical and not fuel or vacuum related.

PEACE
 






Coolant Temperature Sensor

My truck has been showing code 117 since I got it a year ago--I replaced the ect 3 times to no avail--explanation of code is low voltage or grounded--had to replace the battery on Sunday and light has gone away--no more check engine light!!!;) Very happy--i assume the 117 code low voltage refers to my problem--when I bought the truck, the battery was cracked--i just kept patching it with silicone and it never really failed until now--- Just happy to see the cel go away--still have high idle problem---pretty convinced it is lower intake manifold gasket sucking air and a little anti freeze---homemade iac gasket and idle is controllable.
 






When all else fails.............this is what one other poster came up with.



OK.... in regards to the relay, I actually replace all 6 in the relay box every other year religiously. It eliminated a lot of issues so that is now a standard preventative maintenance item. As for the FPR, it had been replaced already and the egr was checked also. I did remove the ignition control module due to there was a service bulletin about it's ground connection and also cleaned every connector and resealed with no benefit.
The fix was the computer, I couldn't find a match local so I went to the Ford dealer and let them check it out. Ends up the processor was running slow, it wouldn't register feedback on time, it would register faults if you disconnected the MAF, ECT or any other sensors. When it would try to tune and adjust, the system wouldn't register faults, it just couldn't keep up with the feedback it was registering. As of now, it has ran for two weeks without issues!
 






Bumping an old thread but I will say that I spent most of Friday dealing and testing for the same issue. Mine was idleing between 1400-2000 when not in gear. Automatic trans... Pull it into drive and it would sit at about 1000 rpm. I messed with and tested as much as I could and got no where. I found a couple vacuum leaks and got those fixed but still no solution. Talk about false hope everytime you find and fix one though! LOL So in the end I finally ended up making a new IAC gasket that was solid. I punched a hole in each side of it the size of a pencil (since that's what i used to make the holes, lol) and put it back together. It idles now at about 900 in park and about 800 or so in drive. I'm in vegas so cold isn't an issue right now being july. This winter we'll see how it runs but for now it's a jerry rigged fix at least to keep me going.
 






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