Help! Engine Light On, P0174 code

[Jake978]

Yep My "Check Engine" Light is On; P0174 (P0174 System too Lean (Bank 2)) code was detected while trying to get an inspection sticker (Mass). So the tech put the dreaded REJECT sticker on my sport trac.

I have replaced the Air filter (No change); next I will try to replace the fuel filter? I have never done this before and wish it was something simpler? Any recommendations before I start this endeavor?

1. Where is it located?
2. Do I need any special tools to remove old filter?
3. Any tips on reducing the fuel pressure, before filter removal?.

PS: When the temperature drops ~<30 degrees and before the engine warms up, it wants to die out, this happens for about the first 2-3 minutes of starting, then finally smoothes out and is OK. To keep it going I have to push on the Gas peddle to keep it from stalling. Again once it warms up it's OK.

Thanks In Advance!

 

[John_Rock]

1. Where is it located?

Inside frame rail just beneath the driver's area.

2. Do I need any special tools to remove old filter?

http://www.explorerforum.com/forums//showthread.php?t=229573

3. Any tips on reducing the fuel pressure, before filter removal?.

http://www.explorerforum.com/forums/showpost.php?p=2015196&postcount=3

PS: When the temperature drops ~<30 degrees and before the engine warms up, it wants to die out, this happens for about the first 2-3 minutes of starting, then finally smoothes out and is OK. To keep it going I have to push on the Gas peddle to keep it from stalling. Again once it warms up it's OK.

It could be the IAC valve sticking.

 

[Jake978]

Thanks for the info!

Found the Fuel Line, just where you said it would be. I need to get a disconnect tool (heard the plastic works better). I'll try the local Auto shop, it's closed today, need to eat some turkey anyway.

Next Question:
I found the relay box, does anyone know which one I need to remove to relieve the fuel pressure?

Also, I was able to reset (OFF) my check engine light by removing the Positive battery terminal for ~10 seconds. Now, yesterday I did replace the Air Filter which was dirty. So I hope it was the combo of the two that did the job? Time will tell. Or at least it stays off until I get my Inspection sticker on Friday. Still going to do the Fuel Filter change out, 50K plus miles.

Later!

 

[brianjwilson]

I've heard of lots of people tripping the inertia switch and cranking the starter for a few seconds. Behind the passengers kick panel (front right side) there is a switch that cuts fuel if you get in a wreck. When it is tripped the red button on top sticks up. I forget how to trip it, there's a button or something on the side.
I've never bothered doing this and never had any problem. Most I've lost is 1/4 of a cup and it's never sprayed out, but I suppose it could.
That trouble code is VERY common on the older 4.0L OHV engines due to bad upper intake manifold (plenum) gaskets. The rubber gaskets wear out and let extra air into the intake manifold causing it to run lean. My 97 Explorer 4.0L OHV had this problem and wouldn't run properly when it was cold. It would try to stall out, felt like missfiring, etc. When it warmed up, the rubber gaskets expanded just enough to seal properly and it drove fine.
BUT... Check the obvious things first. Any intake/vacuum leaks could cause this code.
It seems more common that this code is from a leak in the intake system rather than a low fuel pressure issue.

 

[John_Rock]

Next Question:
I found the relay box, does anyone know which one I need to remove to relieve the fuel pressure?

There's a schrader valve up at the fuel rail in the engine bay that you can relieve the pressure with.

 

[brianjwilson]

Here is info on the intake manifold gaskets...
http://www.explorerforum.com/forums/showthread.php?t=171819
Again I'm not sure how much it differs on the SOHC 4.0L. Probably much the same with the plastic intake manifold.
When you say the truck wants to stall for the first few minutes, is it only rough at idle? If you start it up cold and try to drive, does it have good power and run smooth?
If it is just at idle, it could very well be the idle air control valve like Johnstone said. You can clean them but it sometimes causes them to get worse, most people replace them. It could also be a bad gasket on the IAC valve.

 

[Jake978]

Finally got the Massachusetts Inspection sticker, I felt like I was in the movie "Groundhog day".

The last thing was to pass the "On-Board Diagnostics (OBD) Monitor Results". You need 4 of the 5 categories to be ready. The reason for the wait was whenever the battery or Computer system is reset it takes about 1 week of combined (highway and intown) driving to collect enough data for these systems to be a go.

On-Board Diagnostics (OBD) Monitor Results:

1. Exhaust Gas Recirculation (EGR) Monitor - Ready
2. O2 Sensor Heater Monitor - Ready
3. O2 Sensor Monitor - Ready
4. Catalyst Monitor - Ready
5. Evaporative System Monitor - Not Ready