I have a 2001 F150 Super Crew 5.4. I had a leak where the water transfer connects to the intake manifold. I decided to get a new manifold rather than trying to repair it. The new manifold from Dorman came and the gaskets were built into the manifold. I torqued the manifold to specs. I replaced everything and it starts fine.

I can hear what sounds like a leak, but can't find anything. I checked every hose that is connected and they are all snug and connected. I had the check engine light checked and it said it was running lean on both sides (p0174, p0171). Also a p0122. I thought something might have damaged the Throttle Body Position Sensor, so I replaced it...but no change.

I'm still driving it everyday because I need to. It won't change gears so smoothly sometimes. The most noticeable problem is that the A/C doesn't work. It just blows hot air. And the worst part about it is...it does it even when the air isn't turned on! I just go around with the windows down...in 95+ degree heat...with hot air blowing!

Any help would be appreciated. This is my first time to attempt a manifold change out.

Any ideas on what I should check?

 

171, 174 are vacuum leaks.............. both sides, so it is common to the manifold. Look at all vacuum hoses....... how about the one on the BACK side of the manifold, did you get it plugged back in ? Maybe the fitting is broken ?

 

air conditioner don't work ?... I assume the clutch is not engaging on the compressor ? Is the wire plugged into the compressor clutch ? Do you have 12 volts at the clutch wire ? If not, do you have R134 pressure on the LO- HI side ? IF you have 12 volts, did you bend the plate/ spring on the clutch pulley ?

 

Thanks for responding! I did check the one on the back. To me that is where it sounds like it's coming from. It is connected. The fitting is a new one that came with the manifold. I will check it again though.

I didn't have to unplug or uninstall the A/C to do the job, but I will check the wiring. If I remember correctly, the A/C would start to get cool, but then would go hot....like heater hot...not just outside air.

Is there anything special that I need to do when replacing the Positioning sensor, or just take the old one off and put the new one on?

 

The vacuum line on the back is suspect.. Easy to break or pull apart when installing.

for the AC... see if the compressor stops running or shuts off, then gets hot.. IF compressor is running, then you have a blend door problem. If the clutch is not running then you might have low psi or excess clutch clearance..

I don't know much about the TB position sensor. I would think that would have more to do with idle and not vacuum leak.... again 171 - 174 are NORMALLY vacuum leak.