My new to me sport trac

[Larry Holmes]

Happy Hanukkah

Thank you and Happy Hanukkah to you too.

 

[mcarroll02]

Thank you and Happy Hanukkah to you too.

Shabbat Shalom

 

[mcarroll02]

Wellnit most definately was not a crank sensor. Was headed to town to pick up some electrical stuff for my cabin. Got about 5 miles from the house(after it had ran at idle at home perfectly for a half hour) and it lost powe, misfired real bad and then quit. Coasted into a side road...after a few tries i finally got it to restart and it ran like crap for a few mins and then got better. Drove home and it did ok. Pulling in my driveway it almost wouldnt pull the hill in my drive. Got it home and am about to run a quick scan before i hop in the f250 and go get my stuff.

 

[mcarroll02]

Codes are as follows:
P0306 cylinder 6 misfire
P0174 system lean bank 2
P1150 lack of ho2s21 switches fuel trim at limit
P1151 lack of ho2s21 switches sensor indicates lean
P0171 system lean bank 1
P0303 cylinder 3 misfire

 

[mcarroll02]

been sitting here at home with it running, moving about in the drive and its running smooth for a while the it will stumble and misfire a few times and then go back to running good

 

[mcarroll02]

Ill check on it more when i get home. I gotta run to lowes.

 

[cadman777]

Codes are as follows:
P0306 cylinder 6 misfire
P0174 system lean bank 2
P1150 lack of ho2s21 switches fuel trim at limit
P1151 lack of ho2s21 switches sensor indicates lean
P0171 system lean bank 1
P0303 cylinder 3 misfire

Great, thanks.
Can you get Fuel Trims (STFT & LTFT)?

Have you smoke tested it yet?
Mine was leaking intake plenum seals, very common on these.
Had to spend a pricey 90 bux on new plenum bolts from Ford, b/c they're 'special'.
It's not a difficult job, it's just a big job.
Gotta remove everything on the top to get the plenum off.
Took me 8 hours, mostly due to inspecting and cleaning up everything.
Plus, I put in new timing chain tensioners (Motorcraft), valve cover gaskets, spark plugs, and all the o-rings and other seals that were on the top end.
When the plenum was off, I could see the valves.
B/c I use Jectron fuel system cleaner every year, they were spotless.
There was around 90k miles on it when it needed this work.
Now there's about 150k miles on it, and it still runs good, except it needs the timing chain cassettes.
The plenum seals used were Felpro blue.

 

[Pat in RI]

Just a thought but after reading several forums and recalling that my 86 F 150 had the same symptoms, it turned out to be a rusty clogged fuel filter. Can you confirm you have good fuel pressure at the rails?

 

[cadman777]

Just a thought but after reading several forums and recalling that my 86 F 150 had the same symptoms, it turned out to be a rusty clogged fuel filter. Can you confirm you have good fuel pressure at the rails?

It's possible, but...
If he has those high LEAN fuel trims on one bank, then it sounds to me like there's a vacuum leak.
But we won't know without seeing some live data.

 

[mcarroll02]

Great, thanks.
Can you get Fuel Trims (STFT & LTFT)?

Have you smoke tested it yet?
Mine was leaking intake plenum seals, very common on these.
Had to spend a pricey 90 bux on new plenum bolts from Ford, b/c they're 'special'.
It's not a difficult job, it's just a big job.
Gotta remove everything on the top to get the plenum off.
Took me 8 hours, mostly due to inspecting and cleaning up everything.
Plus, I put in new timing chain tensioners (Motorcraft), valve cover gaskets, spark plugs, and all the o-rings and other seals that were on the top end.
When the plenum was off, I could see the valves.
B/c I use Jectron fuel system cleaner every year, they were spotless.
There was around 90k miles on it when it needed this work.
Now there's about 150k miles on it, and it still runs good, except it needs the timing chain cassettes.
The plenum seals used were Felpro blue.

Ill pull fuel trims later, working on getting electricity to my cabin today. No on the smoke test. Dont have a way to do that. I replaced all intake manifold gaskets when i replaced the valve cover gaskets about 2 years ago. Replaced tensioners at the same time. I know it needs the cassettes replaced. Dont have the time and money to deal with that at the moment. Fuel filter was replaced close to 10k miles ago....next to last oil change. And i run felpro gaskets for everything except head gaskets. Those i prefer the cometic mls gaskets.

 

[cadman777]

Sounds like you have most of the bases covered.
I guess the fuel trims are the next thing I'd look at to get moving in the right direction.

 

[mcarroll02]

It's possible, but...
If he has those high LEAN fuel trims on one bank, then it sounds to me like there's a vacuum leak.
But we won't know without seeing some live data.

Lean on both banks.

 

[swshawaii]

With four other DTC's it's unlikely your only issue, but check the notoriously failed PCV elbow.
If never replaced after over 20 years it's probably toast anyway. GL
https://www.explorerforum.com/forums/threads/p0171-p0174-4-0l-sohcs-sport-sport-trac.314670/

 

[mcarroll02]

Replaced pvc valve and elbow last year.

 

[cadman777]

The best way I know of to rule out vacuum leaks is to smoke test it @1-2psi.
You could also have an EVAP leak.
But when you smoke test the EVAP system, you have to be very careful not to exceed the mfgr's spec on pressure.
What I do when there's this kind of problem is look at the fuel trims, and check the O2 sensors, and fuel pressure on the rail.

I just worked on a VW Jetta that was running weird.
Turns out the MAP sensor was soaked in oil from the PCV valve letting oil into the intake.
The only way to fix that was add a catch-can to the PCV line going from the valve cover to the intake manifold.
It's a common problem on some vehicles, esp. the turbo diesels and higher performance engines.
The way I figured out what was wrong with that thing was to remove the MAP sensor, which led to removing the throttle body to look inside the intake.
Then I read VW forums and everyone was putting a catch-can on their Jetta.
So I found someone who told which catch-can he used and that worked, and I found the same thing on fleaBay for a cheap price.
Worked like a charm.
Anyway, there was about 4 ounces of oil sitting in the bottom of the intake manifold when I removed the throttle body and looked inside.
But even after I fixed the PCV valve, PCV line and added the catch-can, (besides doing a recall upgrade on the aux air system), it still ran bad.
So I decided to smoke test it, and that's what showed me there was a small leak in the PCV diaphragm that I just installed.
Turns out it was not seated properly on one spot (it was kinked).
Fixed that and now it runs like a Singer sewing machine.

Anyway, I'm not saying that's what's wrong with your XLT.
What I am saying is that you have to start somewhere, and the best way to do that is process-of-elimination.
And fuel trim and O2 sensor data are a good starting point b/c they lie at the heart of fuel metering, besides ECT and MAP or MAF (in your case).
Plus, they're easy to look at b/c 'it's the law' for OBDII.
Another easy test I do first thing is check fuel pressure at the rail.

Runnability problems are tough to diagnose.
But starting with basics and using a methodical approach works for me almost every time.