I just got this truck from my Brother in Law. Great condition.

We had trouble getting it to pass emissions. The dreaded P0171 and P0174. He went through and replaced the EGR and the MAF as well as cleaning the IAC, IAT, tes for vacuum leaks and checking the PCV valve and all connected hoses. Still no go.

I searched and searched this board looking for more answers. The only thing left was O2 sensors, new IAC and Cats. Too rich for my blood. He just gave me this rig. That's right, FREEBIE! I didn't mind spending some money but when you've been laid off for 4 months, pickins is slim.

What finally worked for me was 1/3 pint of SEAFOAM into the brake booster vacuum line, turn truck off, wait 5 minutes and start back up. I also poured the remaining 2/3's in the 1/4 full tank(I know this is a high concentration). Reset the codes and drove home. Passed the emissions test the next day and the Check Engine light has not come on yet. Knock on wood.

My remainig problem is that every once in awhile, when below 40 degrees, the truck will lose oil pressure, the oil pressure light will come on and it will start to idle rough. A light tap on the accelerator and it goes away temporarily. My brother in law did warn me about this so it is ongoing. I had hoped that the codes and this would go away together. yeah right.

I have searched again for this same problem and have not found anyone with my matching symptoms.

I checked the IAC for voltage from the harness and it checked good. I thecked OHMs resistance at the IAC and it checked good. Removed the IAC and inspected the inside to see a light build up but nothing terrible. I've seen worse. I cleaned it and reinstalled it.

No codes. Any ideas? I have seen what a bad IAC acts like, I was a fleet mechanic for Georgia Power and we ran nothing but F150's.

 

Mine is doing the same thing, mostly in the cold weather (2000 w/135k miles). This is a fairly common issue with the pressure sending unit. I plan to put a new one in this weekend and will let you know how it goes...

 

cool. But wouldn't that just saw what the pressure is and not cause it to drop. Or would that send a message to the PCM cusing RPM's to drop? I'll be anxious to hear the outcome.

 

I lost my oil pressure sending unit about 2 years ago when it was -15. The Expedition ran fine other wise. The Expedition only had 60000 miles on it though. Good luck

2000 Expedition EB 4x4
2000 Excursion LTD V10 2wd

 

GaWag,

I didn't get a chance to replace the sending unit this weekend afterall so I'll have to keep you posted. The pressure gauge is actually on or off, It's a dummy light in the form of a gauge. Your problem could be different; if you see a change in the way your engine is running when the light comes on, you could have a bigger issue...

 

What's the theory here? - injectors were gooked up and not allowing enough fuel to flow, causing the lean condiction? Seafoam opened them up and now they are good to go??


(I'm interested, as my Navi sets ONLY the P0174 about every three months. When it sets the code, LTFT for bank1 is around 5% while the LTFT for bank2 is in the 22 - 24% range! It runs fine, so I clear the code and I'm good for another 2 or 3 months. since both banks don't go lean, I was suspecting either an intake manifold leak or exhaust manifold leak on bank2, but its too darn cold and snowy to crawl under and over it now.)