Hello All,
New to the forum. I want to wish all a good day.
Anyway,
I have a 2001 F150 XLT with 5.4L Triton that has 160K Miles on it.
I just bought it about 2 months ago with no warranty.
I had problems with the Downstream O2 Sensors having issues but wound up replacing the wiring harness that was corroded and giving poor connections back to the PCM and also replaced both DS O2 Sensors as well.
Anyway no more O2 Codes. However I have been getting Bank 1-2 lean codes as well that would come and go.
I can clear them and everything is fine. The code only comes back if I have passengers in the truck with me it seems.
I re scanned the code and have the Freeze frame Data which I have included in the bottom of this post.
Also, I have noticed that the engine revs up when I place it in gear and sometimes stays up above 1K RPM then slowly falls down to 750 RPM.
I called myself checking for vacuum leaks by using propane gas around all the engine vacuum hoses and intakes where I could reach.
This truck is a 4X4 and has big mud grips on it and this problem is eating me alive on fuel mileage.
I plan on rechecking the PCV line elbows and the small vacuum again this weekend.
I can tell somebody has been mucking around this engine before but I cant tell what was done.
Anyway, I am thinking I have an intake issue that may be temperature related.
I really need assurance that I am looking for a vacuum leak and that hopefully I can repair it myself.


Thanks guys and didn't mean to run on like that.....




FREEZE FRAME DATA
P0174
Fuel Sys 1 CL
Fuel Sys 2 NA
Calc Load 61.5
ECT (Deg F) 168
STFT B1(%) -3.1
LTFT B1(%) 21.8
STFT B2(%) -5.4
LTFT B2(%) 21.8
Eng RPM 2156
Veh Speed 48


P.S Could somebody explain what this stuff means?

Thanks!

 

This being you first info some, things are only possibles at this time until you get to check more items.
One thing that is out of spec is the engine temp at 168°. This is to low. Should be near 200°. This may be causing the PCM to over fuel the motor and also causing the high idle issue.
With extra weight, the load is greater, you use more throttle opening. It seems to appear your issue could be marginal so the PCM goes in and out of fuel table spec per driving cycle.
It's an old trick to run the motor colder looking for more power but on these computer controlled engines it shifts fuel tables, uses more gas and can cause other issues such as cold start etc.
I would replace the thermostat with the correct rated temperature replacement and drive awhile to see if there is any change.
Look over the intake hose from the air meter to the throttle body for air getting in and unaccounted for by the air meter.
At this point you may have more than one issue to sort out from previous ownership.
.
ECT is coolant temp. STFT means short term fuel trim in % away from normal.
LTFT is the same but seperate tables for longer term records for such reasons as engine wear, high loads over longer periods, differences in fuel etc.
Good luck.

 

Thanks for the reply Bluegrass.
It does look like the thermostats been changed on it.
Do you recommend a factory one or a Stant replacement?
Thanks.

 

Either one should be ok.
Stant is a old brand on the market.

 

Doesn't matter as long as it's the correct temperature - which is 190 to 195.

 

I went through the truck again checking for leaks with propane gas and I checked every hose and elbow I could find as well as going around the intake spacer. I cleaned the mad sensor with no residue electrical cleaner and a soft paint brush. It's now pretty and clean. I will replace the thermostat and air filter tomorrow and clear the code.
Thanks for the help so far.

 

Use a 192/194, - For some reason, these engines like those best.

 

It's been a week now and no cel. I found my vac leak to be in the 4x4 control valves on the firewall to be leaking. Noticed that I was unable to engage the front axles and checking I found the source of my leak and repaired my fed and the same time.
So far so good.

 

Yea, your speaking of the 4wd solenoid lines. Pink and Blue lines. They have been known to crack and break between the battery box and firewall.

 

I have a 2000 Lincoln Navigator has a code PO174 fuel pressure 40 psi sprayed carb spray to check for vaccum leak none found I been told if it has a plastic plenium it could be a gasket leaking and causing a lean condition does anyone no of a fix

 

Yea, NEVER use carb spray lol. You'll create more problems, - since it melts rubber and plastic. It's most likely to late now, - oh well, next time. For now -

I'd replace everything you hosed down with carb cleaner, - also any sensors in the vicinity of. Just a mist of that stuff can smoke the diaphragm in the EGR valve and burn the ribbon inside the TPS. You might want to remove the top end and just replace everything that's been eaten away.

Whom ever told you to do this needs an *** kicken lol.

 

heyy guys! i have a 2000 f150 with P0171 & P0174 codes. it also pings when i accelorate which sounds horrible. ive used a better grade of gas and had a motor vac done to clean out the carbon, ive had it checked for vacuum leaks and i've changed my maf sensor and it's still pinging... ive changed the fuel and air filter recently.
does anyone have any suggestion as to what i should do next?

thanks

 

Believe the codes.
They are telling you you have a severe leak at some point that is making the A.F ratio very lean and causing the pinging.
I would be looking first at the EGR system.
An exhaust leak here will 'advance the timing' and 'cut back fuel' even without an air leak and cause the issue.
The OX sensors detect this and try to richen up the fuel as the codes tell you, trying to counter the condition is can't do.
Another cause could be the knock sensor but you should get a code for that.
It's there, you just have to find it.
Good luck.

 

You have a bad vac leak. Check the PCV system very good. Also in your case IIRC the earlier 4.2's had intake gasket issues at the lower intake to the heads.

here is some reading for you; http://www.aa1car.com/library/ford_lean_codes.htm

 

ya it's a V6 4.2L... so do another good check for leaks?

i didn't notice that i posted in the wrong forum. lol