DHCampbell

2001 f150 xlt supercrew 4x4 5.4
All stock except for lift and tires.
Intermittently revs up and down at idle.
Can't figure it out. Just replaced the fuel filter
And the spark plugs and wires.
Also fixed some vacuum leaks.
I heard there is o-rings on the injectors and one
Of those leaking may cause the prob. Does this sound right?
SES light is on and the code is p0147.
I've been poking at it with a stick but the problem remains.
Also the heater won't get hot. Only a little warm.
Could this be related?

Matt D

It could be a crudded up Idle Air Control (IAC).

Look on Rockauto.com for your truck, and you will find a picture. Replacement is about a 10 minute job, including 5 minutes for drinking an adult beverage.

You can always remove yours and clean with carb cleaner. For $30ish in parts, I just replace them.

-Matt

joe_83

P1047 usually means something is wrong with 02 circuit or sensor.
Here is a pretty good write up on it, and it would certainly cause rough idle.

http://www.obd-codes.com/p0147

Kokeshx4

for your heater it may be the blower motor need replacing. does it rev up and down at all idles or just hot or cold or first start of day??

DHCampbell

Revs up and down just at idle after about 10 minutes after first start of the day.
I gotta hold the gas pedal down a little to keep it running.
Runs fine until I get to about the third or fourth light down the road.
After that struggle at that light its usually good for the rest of the day unless it sits for a long time in between drives

DHCampbell

So I cleaned out the IAC valve and it ran perfect for a couple days. Now the problem is back. I never reset the comp though.

Bluewar02

Hi did you ever figure out the problem? I have the same thing going on can't I can't figure it out

Jeffrey K

The Codes is for a Heater circuit of an O2 sensor Fault. The HO2S did not get into closed loop quick enough for the system. which, in turn illuminates the check engine light. Since this is a feed back system, the HO2S is an important input for the computer to know what the fuel mixture, weather the engine is running lean or rich. As you drive the HO2S heats up and the signal becomes correct. This would explain how the rough running symptom goes away in till the exhaust system cools down again. The heater circuit is controlled buy the pcm and is ground side switched. Bank 1 Sensor 2 has a VT/WH wire going to the HO2S and a WH/BK wire going to the PCM. With the key on, using a DVOM you should have more then 11.8Volts on the VT/WH. this ensures you have voltage to the heated sensor circuit. Next i would measure the resistance using your DVOM across the sensor heater circuit, it should be between 3 - 30 Ohms. if the resistance is more or less then that, replace HO2S. , Note: Mace sure you are checking resistance on the right pins of the HO2S, easiest way is to match the pins connecting to the VT/WH wire and WH/BK wire. I hope this Helps.

Andrew48

My truck will rev up and down while idling to, plus my heat won't get hot like it should. The heat will just get warm. Is there any way those two problems are related? I'

noeaguinaga83

My truck is doing the same thing.. Revs up and down at idle and when down shifting it starts a little above 1200 rpm at stop for about ten seconds then eases down..ses light is on.. Dealer says o2 sensor.?? I have a 2003 4.2