Real High Idle and Transmission won't Shift
#1
Real High Idle and Transmission won't Shift
I picked up this truck last weekend from my father in law. The truck had basically been sitting for the past 8 years. I got it running and drove it 3.5 hours back to my house.
The motor was dirty as crap and the engine would stumble and stall. So this week I proceeded to clean the motor with some degreaser and my pressure washer and also clean the IAC.
Afterwards I cranked it up and took it for a drive to dry everything out. As the motor warmed up I noticed that I was basically idling at 30mph. As I turned around to come back home it was still idling me at 30mph. I put it in park and it idled normal for about 10 seconds and then the idle went up to what sounds about 2500 RPM or so (no tach).
I figured that the IAC was shot so I went and bought a new IAC and put it on. I took it out for a test drive and and I had the same results. I brought it home and unplugged the IAC while it was idling high and it dropped down to what sounded like 300 RPM. I plugged it back in and it went back up high.
The transmission which is a A4OD (new to the F150, so if that is not right don't flame me) does not want to shift on it's own. I have to get it up to a very high RPM and then let off the gas to make it shift.
Neither of these problems were happening until I pressure washed and changed the IAC, which I did basically one after the other.
I have taken my stethoscope and attempted to listen to the vacuum hoses and did not really hear anything, but I am sure I could have missed something.
Anybody got a clue as to what is going on?
thanks,
michael
The motor was dirty as crap and the engine would stumble and stall. So this week I proceeded to clean the motor with some degreaser and my pressure washer and also clean the IAC.
Afterwards I cranked it up and took it for a drive to dry everything out. As the motor warmed up I noticed that I was basically idling at 30mph. As I turned around to come back home it was still idling me at 30mph. I put it in park and it idled normal for about 10 seconds and then the idle went up to what sounds about 2500 RPM or so (no tach).
I figured that the IAC was shot so I went and bought a new IAC and put it on. I took it out for a test drive and and I had the same results. I brought it home and unplugged the IAC while it was idling high and it dropped down to what sounded like 300 RPM. I plugged it back in and it went back up high.
The transmission which is a A4OD (new to the F150, so if that is not right don't flame me) does not want to shift on it's own. I have to get it up to a very high RPM and then let off the gas to make it shift.
Neither of these problems were happening until I pressure washed and changed the IAC, which I did basically one after the other.
I have taken my stethoscope and attempted to listen to the vacuum hoses and did not really hear anything, but I am sure I could have missed something.
Anybody got a clue as to what is going on?
thanks,
michael
#4
I just sprayed carb cleaner over all the vacuum hoses to see if it would do anything. There was no change that I could hear in the motor.
I then pulled the codes again. I had a code 121 "Closed throttle TPS voltage higher or lower than expected." and a 111 "System pass".
With the truck idling, the idle was fine for about 10 minutes until the truck got warmed up then the idle went racing high again.
Any ideas?
thanks,
michael
I then pulled the codes again. I had a code 121 "Closed throttle TPS voltage higher or lower than expected." and a 111 "System pass".
With the truck idling, the idle was fine for about 10 minutes until the truck got warmed up then the idle went racing high again.
Any ideas?
thanks,
michael
#6
#7
Being new to the F150, question about the TPS.
Where is the TPS located? I remember reading some post that I think were from a 5.0 that said it was inside the intake manifold.
How do you check the TPS voltage?
I have a Haynes manual on order, but it will be a few more days till it gets here and I really need to get this thing running right so I can take it through inspection.
thanks,
michael
Where is the TPS located? I remember reading some post that I think were from a 5.0 that said it was inside the intake manifold.
How do you check the TPS voltage?
I have a Haynes manual on order, but it will be a few more days till it gets here and I really need to get this thing running right so I can take it through inspection.
thanks,
michael
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Thanks
I just wanted to say thanks to all the members who post. This site has saved me 1000s over time and so I decided its time to give back. I had the same problem with my 2002 f150 2wd 4.6. Driving home I noticed it wasn't shifting, I limped home (5 mins thankfully) at 40km per hour. Put it in park and it idled at 2500. I checked this site and sure enough I found this thread. I removed the plastic motor cover and tapped on the tps with the nut driver. I also wiggled the wires leading to the connector for the tps. Restarted the truck and its back to running great. I know this isn't a permanent fix but at least I can be fairly sure what the problem is. Tomorrow I'll replace the tps and clean the connection if required. Also fyi the service engine soon light didnt come on. Thanks again everyone!
Steve
Steve
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Adrianspeeder
Last edited by adrianspeeder; 10-29-2013 at 01:43 AM.