EastTnMike

Hey guys, this is a 2003 F-150, FX4 4.6 Got into it Friday evening and Service Engine light came on. Cranked it up and started at 2000 rpm's. Tried starting it several times and still stayed at 2000 rpm's. Searched for broken or cracked hoses and can't find one. I don't think that the throttle cable is sticking. Did a lot of research on some older threads here on the forum and many suggest that the IAC valve is many times responsible. ? I have included a photo. Can someone point out the IAC valve for me. I have placed three pieces of blue tape. One on what I think may be the IAC valve, (left one) and one on a hose and another where this hose connects. Please identify this hose and what it connects to. I did remove this hose while engine running at 2000 rpm and the rpm shot up to 3000 rpm's. Thanks for your help. Mike

Tackle

You can unplug it while the engine is running. If it drops to 500 rpms or so, replace it. I'd look else where though. What are your codes? How about the hose from the pcv to the back of the throttle body driver side valve cover is where it starts)? Pull it and look for cracks or a hole at the bends. Sounds like a vacuum leak.

EastTnMike

Hi Tackle, thanks for the response. I took your advice and unplugged the IAC valve with engine running. Engine stumbled and died. Died every time I unplugged it. As I was doing this a friend was coming with a code reader. It gave a 1120 code that he said was throttle position sensor. Our codes here on the sticky say P0122. TPS circuit low input. The code reader man came in a 2001 F-150 5.4 so I asked him if he minded to unplug his IAC with the engine running. Unplugged it and engine continued to run the same. So I plan to get a new IAC valve tomorrow for mine. Thank you for the direction and I'll let you know how it goes with the new IAC valve. Hopefully that will be the cure. Thanks, Mike

jstockert

I would check the tps connector first and if connected good I would change tps first.

P1120 Ford - Throttle Position Sensor Out of Range

Possible causes
- Faulty throttle position sensor
- Throttle position sensor harness is open or shorted
- Throttle position sensor circuit poor electrical connection
- Throttle position sensor not properly adjusted

When is the code detected?
Malfunction is detected when voltage from the sensor is sent to Engine Control Module (ECM) is out of range.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P1120 Ford Description
The Throttle Position Sensor (TPS) responds to the accelerator pedal movement. This sensor is a kind of potentiometer which transforms the throttle position into output voltage, and emits the voltage signal to the Engine Control Module (ECM). In addition, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal to the ECM.

EastTnMike

First thing this morning I went to the local Ford company to get a IAC valve and a TPS sensor. They had neither in stock but could have by next day if I placed an order. Picked up a new TPS at local parts store. Parts store did not have the IAC in stock either. First thing I did was unhook negative side of battery. The parts store suggested trying to clean the IAC while I waited for the new one to arrive late this evening. So I took it off and cleaned it out best I could with throttle body cleaner. I saw very little carbon in it. I'm thinking if I don't hook everything back up and see what it does I won't know if the cleaning had any effect. ( I've not put the new TPS on yet). Well it fired up and ran perfect. I'll still get the new IAC this evening and go ahead and put it on as well as the TPS. Thank you all for your help. Mike

Tackle

Glad you got it figured out.