High Engine Idle Problem
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From: Deepwater Mo.
High Engine Idle Problem
Greetings, Folks 
I cranked my 1992 F150 with a 5.0 EFI up today and the throttle is acting all weird.
I'm not able to drive it in the condition that it's in. Here are the symptoms of the problem.
It has trouble cranking and and stays rev up about 3,000 RPM. "High Idle" It will not idle normal. It sounds like its cutting out a little. If it does rev back down to normal condition it will die. We tried driving the vehicle down the road and it cuts out like its running out of gas.
I unplugged the battery and has no effect. We checked all the lines, and seem to be in good condition. We tapped on the throttle body, unplugged the condenser next to the coil and the truck still runs the same. Coil is really hot.
Around 60mph the speedometer starts to screw up. Does the Speed Control Sensor in the rear end of the f150 have any thing to do with this problem? What other problems can you think of that might be wrong with the vehicle?
Any help would be appreciated on the finding a solution to the problem.
Thanks for your time.
I cranked my 1992 F150 with a 5.0 EFI up today and the throttle is acting all weird.
I'm not able to drive it in the condition that it's in. Here are the symptoms of the problem.It has trouble cranking and and stays rev up about 3,000 RPM. "High Idle" It will not idle normal. It sounds like its cutting out a little. If it does rev back down to normal condition it will die. We tried driving the vehicle down the road and it cuts out like its running out of gas.
I unplugged the battery and has no effect. We checked all the lines, and seem to be in good condition. We tapped on the throttle body, unplugged the condenser next to the coil and the truck still runs the same. Coil is really hot.
Around 60mph the speedometer starts to screw up. Does the Speed Control Sensor in the rear end of the f150 have any thing to do with this problem? What other problems can you think of that might be wrong with the vehicle?
Any help would be appreciated on the finding a solution to the problem.
Thanks for your time.
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From: Deepwater Mo.
All the information below is what I found by surfing the forums. I will compile all the information I can on this post about the issue I am having with my 1992 F150 5.0 EFI /w a E40d Transmission.
Possibility #1
Fast idle is many times caused by a engine intake vacuum leak, use a can of carburetor spray and spray the top of the engine for leaks, if u hit one u will hear the engine change idle speed, also look for leaking vacuum hoses.
You can also use a handheld vacuum pump/gauge to test each vacuum circuit. There are numerous vacuum reservoirs on these trucks that are quite capable of causing a vacuum leak.
The first is the large metal reservoir on the passenger side fender. It looks like a juice can. It rusts through on the bottom side. The second is a small metal reservoir located behind the driver side head light for the vacuum operated cruise control. The third is a small plastic reservoir mounted on the blower case for the heater/AC/vent. It is plastic, but it can crack. Do not forget the yards of plastic vacuum tubing under the hood. Each one can pass the "spray" test but in reality they can have dozens of small porous cracks along their length that when added up cause a large vacuum leak.
I found the cruise control and HVAC reservoirs were the largest contributors to the high idle. The rest of the contributors were those pesky plastic vacuum lines and a bad upper intake gasket.
The link below has some decent pictures of those pesky lines.
http://www.fordtruckclub.net/forum/s...ad.php?p=48736
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Possibility #2
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Possibility #3
IAC motor. Might be screwing up, closing tight which richens the mixture and increasing idle speed.
Unplug the Idle Air Control (IAC), located on the side of the throttle body and see if motor dies (it should).
If it stays running it's not working. Take it off(two small bolts 8mm socket), clean it out with brake clean, make sure the valve is free(moves easily)
Does the idle still remain high? By unhooking the IAC you are taking the PCM out of the equation. Also, you can pull the hoses off of the throttle bodies (dual TB setup) and just before the butterflies you'll see a hole in each TB. That is the hole that the IAC uses to increase the amount of air going into the engine. Use your fingers to block those holes off and see if the idle drops to around 500 RPM give or take.------------------------------------------------------------------------
Possibility #4
If your truck is equipped with a MAF. Clean the Mass Air Flow sensor. Try disconnecting the MAF while its running and see what it does. If it goes to normal idle then there's your problem. Same goes with the Idle air control sensor. What the computer will do is realize that it isn't getting a signal from the sensor and should idle like normal instead of getting the wrong signal that causes the truck to idle to high.
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Have you checked for codes?
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Possibility #5
The only things I can think of that would affect your idle is the IAC and the TPS. I am leaning more towards the TPS, Throttle Position Sensor. The only way to fix it is to go to the ford dealer and get a new one. remove the throttle body and replace it.
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Possibility #6
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Possibility #7
The other idea (throttle stop tampered with)
you can pull the air intake hoses off of the throttle body and look at the butterflies while the engine idles. They should be almost closed. If they are sitting open, back the stop screw off until they almost close - the idle should come down as you turn the screw.
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Possibility #8
Check and see if the bottom of PCV valve fell out. Sometimes this happens with plastic valves. If it has overdrive transmission then it will not have vacuum hose to transmission.
Possibility #1
Fast idle is many times caused by a engine intake vacuum leak, use a can of carburetor spray and spray the top of the engine for leaks, if u hit one u will hear the engine change idle speed, also look for leaking vacuum hoses.
You can also use a handheld vacuum pump/gauge to test each vacuum circuit. There are numerous vacuum reservoirs on these trucks that are quite capable of causing a vacuum leak.
The first is the large metal reservoir on the passenger side fender. It looks like a juice can. It rusts through on the bottom side. The second is a small metal reservoir located behind the driver side head light for the vacuum operated cruise control. The third is a small plastic reservoir mounted on the blower case for the heater/AC/vent. It is plastic, but it can crack. Do not forget the yards of plastic vacuum tubing under the hood. Each one can pass the "spray" test but in reality they can have dozens of small porous cracks along their length that when added up cause a large vacuum leak.
I found the cruise control and HVAC reservoirs were the largest contributors to the high idle. The rest of the contributors were those pesky plastic vacuum lines and a bad upper intake gasket.
The link below has some decent pictures of those pesky lines.
http://www.fordtruckclub.net/forum/s...ad.php?p=48736
------------------------------------------------------------------------
Possibility #2
High idle is generally caused by a vacuum leak. Sounds like you have a LARGE one. The brake booster is a likely suspect. Pull its vacuum hose and plug the engine side. If the idle drops, replace the booster.
Otherwise, listen around the idling engine for an obvious hiss.
Otherwise, listen around the idling engine for an obvious hiss.
-------------------------------------------------------------------------
Possibility #3
IAC motor. Might be screwing up, closing tight which richens the mixture and increasing idle speed.
Unplug the Idle Air Control (IAC), located on the side of the throttle body and see if motor dies (it should).
If it stays running it's not working. Take it off(two small bolts 8mm socket), clean it out with brake clean, make sure the valve is free(moves easily)
Does the idle still remain high? By unhooking the IAC you are taking the PCM out of the equation. Also, you can pull the hoses off of the throttle bodies (dual TB setup) and just before the butterflies you'll see a hole in each TB. That is the hole that the IAC uses to increase the amount of air going into the engine. Use your fingers to block those holes off and see if the idle drops to around 500 RPM give or take.
Possibility #4
If your truck is equipped with a MAF. Clean the Mass Air Flow sensor. Try disconnecting the MAF while its running and see what it does. If it goes to normal idle then there's your problem. Same goes with the Idle air control sensor. What the computer will do is realize that it isn't getting a signal from the sensor and should idle like normal instead of getting the wrong signal that causes the truck to idle to high.
------------------------------------------------------------------------
Have you checked for codes?
It is normal for the PCM to boost up the idle on start ups, even when its warm, but it should go back down within a few seconds. The link below may help on retrieving codes.
How-To: retrieve trouble codes- OBDI - Ford F150 Forum - Community of Ford Truck Fans------------------------------------------------------------------------
Possibility #5
The only things I can think of that would affect your idle is the IAC and the TPS. I am leaning more towards the TPS, Throttle Position Sensor. The only way to fix it is to go to the ford dealer and get a new one. remove the throttle body and replace it.
------------------------------------------------------------------------
Possibility #6
Try disconnecting the battery for like half an hour to reset the ECU
-----------------------------------------------------------------------
Possibility #7
The other idea (throttle stop tampered with)
you can pull the air intake hoses off of the throttle body and look at the butterflies while the engine idles. They should be almost closed. If they are sitting open, back the stop screw off until they almost close - the idle should come down as you turn the screw.
------------------------------------------------------------------------
Possibility #8
Check and see if the bottom of PCV valve fell out. Sometimes this happens with plastic valves. If it has overdrive transmission then it will not have vacuum hose to transmission.
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From: Deepwater Mo.
This is definitely not my issue!
Another Possibility:
Another Possibility:
Since I picked up this old truck last year, I have had odd on again off again high idle problems. Some times it was OK, other times it would stick high. I just kind of lived with it because it wasn't that big of a deal. Well, after all the work I've been doing it really started to stand out. Well, the day before yesterday it kind of stuck around 2300 rpm, made driving a bit of a challenge. Yesterday it stuck at 4000 rpm. So I figured I better look in to this. My first thought was a problem with the TPS. So I tested it. And it checked out. After checking a few other things I decided I might need to clean the throttle body. So I removed the intake hose to have a look.
Ya, this might be the problem.
Ya, this might be the problem.
<table id="ncode_imageresizer_warning_2" class="ncode_imageresizer_warning" width="640"><tbody><tr><td class="td1" width="20"></td><td class="td2"></td></tr></tbody></table>
This is what I pulled out.
This is what I pulled out.
<table id="ncode_imageresizer_warning_3" class="ncode_imageresizer_warning" width="640"><tbody><tr><td class="td1" width="20">
</td><td class="td2">
</td></tr></tbody></table>
When I bought this truck I gave it a quick tune up, oil change, new plugs, distributor cap and rotor, and a new air filter. When I went to put the new air filter in, I found it like this.
</td><td class="td2">
</td></tr></tbody></table>
When I bought this truck I gave it a quick tune up, oil change, new plugs, distributor cap and rotor, and a new air filter. When I went to put the new air filter in, I found it like this.
<table id="ncode_imageresizer_warning_1" class="ncode_imageresizer_warning" width="640"><tbody><tr><td class="td1" width="20">
</td><td class="td2">
</td></tr></tbody></table>
Yep, no air filter. I'm guessing this is how that paper towel got in there.
</td><td class="td2">
</td></tr></tbody></table>
Yep, no air filter. I'm guessing this is how that paper towel got in there.
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Joined: Jun 2012
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From: Deepwater Mo.
Forum Tread #1
1988 F150 w/ 302 with similar problems. Click the link below, this may or may not help those that are having the same issue.
'88 302 idle too high, out of ideas - Ford F150 Forum - Community of Ford Truck Fans
--------------------------------------------------------------------------
Forum Thread #2
'88 F150 302 high idle, oil pressure drop - Ford F150 Forum - Community of Ford Truck Fans
--------------------------------------------------------------------------
Forum Thread #3
1989 5.0 302 with High Idle. The link below may or may not help those that are having the same issue.
1989 5.0 302 with High Idle - Ford F150 Forum - Community of Ford Truck Fans
1988 F150 w/ 302 with similar problems. Click the link below, this may or may not help those that are having the same issue.
--------------------------------------------------------------------------
Forum Thread #2
'88 F150 302 high idle, oil pressure drop. Click the link below, this may or may not help those that are having the same issue.
'88 F150 302 high idle, oil pressure drop - Ford F150 Forum - Community of Ford Truck Fans
--------------------------------------------------------------------------
Forum Thread #3
1989 5.0 302 with High Idle. The link below may or may not help those that are having the same issue.
1989 5.0 302 with High Idle - Ford F150 Forum - Community of Ford Truck Fans
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From: Deepwater Mo.
Update on the 92 F150
Okay, so I took the truck to Highway 78 Auto in Wylie, TX on Friday just to get them to pull the codes from the computer....It's now Monday. I called them up and they say, "We are having issues pulling the codes from the computer." The mechanics further responded to me that they will try again......
I probably should of just bought a OBD1 scanner and did it my self. These can be purchased at any major parts store ranging from 25-400 bucks. I have also seen a video on YouTube on how to read the codes with out using a scanner.
How to read a check engine light code on a Ford 1983-1995 EEC 4 system - YouTube
I'll keep every one posted on what the mechanic say. I have a feeling they will probably say, "You need a new computer."
Okay, so I took the truck to Highway 78 Auto in Wylie, TX on Friday just to get them to pull the codes from the computer....It's now Monday. I called them up and they say, "We are having issues pulling the codes from the computer." The mechanics further responded to me that they will try again......
I probably should of just bought a OBD1 scanner and did it my self. These can be purchased at any major parts store ranging from 25-400 bucks. I have also seen a video on YouTube on how to read the codes with out using a scanner.
How to read a check engine light code on a Ford 1983-1995 EEC 4 system - YouTube
I'll keep every one posted on what the mechanic say. I have a feeling they will probably say, "You need a new computer."
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From: Deepwater Mo.
Okay, Highway 78 Auto called and got the computer to register the codes.
The error codes are:
The error codes are:
Open fuel circuit= I think that one is from me taking the front fuel tank out of the vehicle and leaving the wiring harness tied up to the frame.
Bad EGR Valve
Throttle Position Sensor
I told them to just fix the Sensor. They are gonna charge a couple $100. Just remember if you do it your self it's $66.00 for Throttle Position Sensor at Auto-Zone for a 92' F150. The only reason I told them to fix it is because it's not drivable in the condition it's in and that they could use the business. I'm happy with their service and would recommend Highway 78 Auto located in Wylie TX for any of your automotive needs.
Throttle Position Sensor
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