I would like to start by saying that I have done alot of reading in advance on this forum and found some very helpful info.
I took what I read and already applied alot of info and steps before I posted a new thread because I didn't want to waste anybody's time.

Here we go !!!!

1998 F150, 4x4, 5.4 w/ 136k. Starts smooth, idles and runs smooth (no skipping, stalling, misfiring, or hesitation.

Purchased used 11/2007 (I got a great buy on it knowing it needed some maitenance work and minor repairs.) (TRUCK LOOKS AWESOME as well !!!)

After a few days of owning it, CEL came on, P0171 / P0174 codes.
I know that is B1 / B2 running lean. At the time, no worries, was putting a standard routine mait. tune-up in it anyway.
Installed, new plugs, fuel filter, air filter, oil & filter, and replaced leaking fuel tank with new one and installed new (Ford) fuel pressure sensor while it was torn down. No gas leaks anywhere and runs even better. Getting 13-14 mpg driving country / hilly rural area. Completed all of this 3/14/08 over a couple of months of part time work on it. (during the couple of months, my CEL would come on, now and then, outputting P0174, my friend would clear the code until I could finish my repairs)

As suggested on this sight, (thank you in advance) cleaned MAF Sensor, and it did look dirty, nice and shiney now.
Replaced, new from Ford, PVC assembly. (incl. pvc valve all the way back to rubber boot connector on TB) I called 2 different dealers and they both said that I couldn't just buy the TB rubber connector. I know, this site said I could and even showed the part and Ford ### on another thread.
$28.00, worth replacing all of it anyway.
I did check all of my vacuum lines and performed the propane tank vacuum leak test at all fittings, TB and Intake. I didn't hear any RPM changes. (at the time, I didn't have the Equus scanner that I do own now, to check for the slight FT changes that could occur.)

BY THE WAY....next time JBREW, instruct us that when we do the propane test, that we have to do this with the FLAME OFF, Burned up alot of stuff at first...., JUST MESSING. I see alot of you on this forum have a great sense of humor.

Still laughing......sorry !!! Can you imaging, flame on,

To my current problem. From 3/14 to 4/15/2008, multiple drive cycles, 792 miles, a couple tanks of gas, had no CEL. On 4/16, just driving along, CEL comes on showing P0174 / B2 lean. Had a friend clear the code again with his SnapOn unit and purchased my Equus.

Here may be my problem (or my confusion) I hope someone can help with my readings or problem.

Using my Equus-3130 Unit, this is what sticks out to me.
Checked on 4/20/08 (I do understand the scanner language & abbr.)
1st start up, idle @ 700 rpm
STFT & LTFT B1 flucuates from 0 to 1.5
STFT B2 fluctuates from -1.5 to -2.3
LTFT B2 @ -5.4 holding constant, no changes

O2S voltage reading's
B1S1, B1S2 & B2S1 all fluctuating &constantly changing between .100 to .825
B2S2 @ almost a constant .520, slowly changes every few seconds +/- .05

MAF reading .775 and increases as I increase the RPM's (as it should from what I understand.)

Go for the test drive to start my drive cycle's to complete my testing from the CEL clearing.

Today 4/21/08
Restart scanning after warm up and idle at 700 rpm's +/- 5
(running truck for 5-10 mins. during test readings)

STFT B1/B2 flucuate from -1.5% to 1.5%
LTFT B1 holds pretty steady at -2.3%
LTFT B2 " " " -5.4%

O2S voltage
B1S1, B1S2, B2S1 all flucuating rapidly between .100 to .825 volts
B2S2 HELD @ .225 and slowly increased to .340 but with no rapid changes over the test run period.

Is my B2 O2 out of limits or NG and how do the numbers look to everyone else.

Sorry in advance for the long thread, but I learned that you techs like alot of info and I did do alot of reading and DIY'ing before I posted.

ANY & ALL help will be greatly appreciated.

Thanks in advance,
TJK in CNY

 

PS: This sight is the best I've seen for automotive help. I have used others in the past, and this one is the best. I am thankful, because this is my 1st Ford Truck.

 

PSS: forgot to tell you, the prior owner cut off the muffler and replaced it with straight pipe. Could this be causing my problems ????

 

Usually the cat efficiency monitors (B*S2) don't fluctuate much. If your cats are working properly the rear O2 sensors don't go back and forth. Not sure how that relates to your lean code but worth researching. See if your scan tool has a BARO reading. Don't know your elevation but there is a chart that lists what it should read at your elevation. This number is inferred by the PCM by using the MAF readings. At sea level, look for 30 in. Hg., or 101.3 kPa, or 158.9 Hz. The higher your elevation, the lower you numbers will be. If your numbers are way low, you have a contaminated MAF and may need to replace. Check it and post back.

 

You did allot of work on her ehh - Yea I agree - best site on the web . U know , I would go ahead and replace the forward O2's - Get the OEM's for sure.

I doubt that's your problem, but it could be - It would be the first time I heard of O2's causing the causing those codes tho.

How does it run ? Next time you are in a warm idle state. Try to pin down the EXACT idle speed. Not cold , but fully warmed up.

Check the fuel pressure and regulator out , since you replaced the filter already.

Sounds like your pretty thorough. If everything checks out and your running Motorcraft plugs, I would hunt for NEW injectors on ebay - you can find a new set of 19's pretty cheap usually. You could always clean yours, but I found type 3's for my 98 that were new for $60 a set on ebay . I think that's cheaper than cleanng them.

You did check your EGR valve and pipe for leaks right ? Well , other than that you covered everything I can think of.

Sounds like srievley has good info above as well .

Good Luck

BTW - sounds like a nice truck ..

 

How do my LTFT's look to you guys. You can see that they stay steady with a negative value.

jbrew, The truck runs really smooth and the RPMS @ warm up run 698-702.
That isn't much of a fluctuation. I checked the RPM'S thru 20 frames
of a scan test when I did it earlier.

The STFT stay pretty constant on both Banks (-1.5 to 1.5 %) Does this look accurate.
The LTFT stay steady, B1 = -2.3 B2 = -5.4 , Does this look correct.

the O2S Voltage on B1S1, B1S2, flucuate constantly between .135 to .810
B2S1 stays between .65 to .725
B2S2 constant @ .440 , no movement
Do these numbers look correct.

I will have to look tomorrow to see if my scanner will give me a BARO reading.
I don't remeber !!! Also my altitude here is 850-1200ft above SL. That was a question someone asked me.

Thanks again for your help.

TJK

 

a new guy that actually knows how to give us all the info, and search first! Welcome!

 

I here yuh Joey - That's great!! Yea , definitely welcome to the site tjk_in_cny.. I haven't seen to many first posts like that one

I asked rpms out of curiosity on my part really - I have the same year/ model 4X4 W/239,000 miles. I purchased new fall of 98. Idles always been @ 720 rpms and it never fluctuated - holds steady, never varies unless there's a problem. - That's how I can tell on this one lol.

I tried running Autolites once and idle fluctuated until 2 cylinders just went dead within 40 miles - Motorcraft plugs fixed it that time. I tried running Borg/Warner O2's in the forward banks once / they were the right cross referenced part #'s - but warm idle would differ from one day to the next and I went from 16mpg to 9 mpg . Fixed it with OEM O2's - went right back to 720 rpm and it's been there ever since.

I don't know about yours , but this thing won't let me stray from OEM replacement parts.

You'll find your problem eventually - I have know idea about the numbers your posting - I don't have a scan tool or use any software diagnostics. I wish I could help more. I posted what I would do on the first reply. That's about all I can think of.

Good Luck and keep us posted

 

Thanks to everyone for the welcome to the site and the info.

Jbrew, I hope your right about finding the problem. It's nagging at me for sure.
I come from an engineering and tech background so I'm used to searching,calling, finding, etc etc. By background is with CNC's (another conversation all together). I state this only to let you guys know that I have some apptitude in tech repair (not automotive tho). Strangely enough, I feel like a newby and that I'm learning all over again, especially trying to fix the newer cars in my family and for friends. Yes, I have been designated as the family wrench. (a curse I think sometimes)
The mechanical repairs are easy compared to figuring out the PCM's, sensor's, logic, etc etc.

Anyway, thanks for listening and offering advice, keep it coming.

Anyone else can chime in any time, appreciate the help.

I have read alot of threads and posts on this site, I enjoy it when someone posts a note like, "it's fixed guys, thanks for the help"

I hope that I am at that point soon. It is definatly a "little bugger" problem.

Thanks,
TJK

 

If the P/O did a crummy job, which would seem to be well within the realm of possibility, the resulting exhaust leak before the first O2 sensor is causing your code.

That is one of the causes of a P0171/P0174 code if you google up said diagnostic tree online...

 

Thanks for the info Alfred. The P/O cut out the muffler after the "Y" pipe which is after the CATS and all O2's. I'm a little confused by what your suggesting.
Also can you further explain the google search and the diag. tree.

Thanks for the help.

TJK

 

Does removing the muffler and replacing it with a straight pipe possibly cause a lean condition because the back pressure is removed when the muffler is removed. Is this correct thinking or am I on the wrong path of thinking.
Also, how do I check for exhaust manifold leaks. A little worried about climbing under there with the truck running. Will the exhaust manifolds leaking cause a lean code.
All the help is greatly appreciated.

Thank You,
TJK

 

Leaky manifolds - Pull fender wells and look for carbon on the heads.

Exhaust system won't cause lean codes. - Like I said before - Fuel pump, injectors, regulator.

When both banks test positive for lean - it's not the MAF , it's usually a leak. But you said you covered all that. So , iduno.

 

Thanks Jbrew,
I will run my truck over to a friend and have him check my fuel pressure from the schrader (spelling?) valve on my fuel rail. Gonna be ticked if my fuel pump is not producing anough pressure, because I just put the tank in a month ago.
I'll have him check the regulator while he's at it. I have a vacuum tester to check the regulator but he will already be in there.
What is the best way to check the injectors ? I can use my fluke meter to check for voltage and ohm readings, but what do I do after that. My Haynes manual gives me all my specs for fuel pressure, voltage readings, etc. The manual isn't clear on checking for proper injector function other than listening to clicking noises using a metal wand to the ear trick. Maybe I will have AJ do the listening. Is there another proceedure you know of.

Thanks.
tjk

 

Not really - You can pick up a noid light at any third party auto supply, there like $5 - that will check pulse. I changed mine because of age and miles . I didn't have any codes. You can go thru the list. I'll post one from this site in my gallery that's here for anyone to use, in case you didn't find it yet. -



These trucks have an intake gasket problem at the heads / leaks/ front of intake by both water jackets.

Just click the camera in the right corner - Unless your using a Firefox browser . If so , you missing out on allot of info. Firefox and f150 online aren't very compatable.