OK Gents....P0171 HELP

[meastt]

First time Post here.....I bought a 96' XLT 2.3L I4. Got it for a great price.......turns out the check engine light was burned out....SO after getting the light bulkb replaced, I have a nice new shiny CEL.

First run and I pulled P1443 and P0171. Used this great site and learned that a swap of the EVAP Sensor eliminated the P1443 code and all Im left with is P0171 "Bank 1 Mixture too Lean.

So far, I have cleaned my MAS, replaced my MAS, New Plugs and Wires (all 8). New Air Filter.

Visually inspected and sprayed almost a whole cans worth of Carb Cleaner on my Vacuum lines looking for a leak that would cause it to run lean and I am now LOST on as to why I still cant beat this P0171 code.

PLEASE HELP.

 

[killj0y]

Check all your vacuum lines. And replace your fuel filter.

 

[Bryan22]

check the plugs, if they look good probably a bad o2 sensor. if you've got over 100k probably a good idea to change the o2 anyway. also check the intake. any leak after the MAF will be letting in unmetered air causing a lean condition. good luck.

 

[meastt]

Well. So far I have checked all the vacuum lines and haven't found anything (using carb cleaner). I have a new MAF, I have replaced all the upper gaskets (intake, throttlebody), I also have a new EGR valve, DPFE Sensor, IAC valve and a new Catalyitc Converter. Also a new PCV as well.

Also checked the fuel pressure and its within regulations

I JUST DONT KNOW WHAT TO DO...

 

[JC 97]

Possible Causes:

Air leaks after the MAF sensor, or leaks in the PCV system

Exhaust leaks before or near where the HO2S is mounted

Fuel injector(s) restricted or not supplying enough fuel

Fuel pump not supplying enough fuel during high fuel demand conditions

Leaking EGR gasket, or leaking EGR valve diaphragm

MAF sensor dirty (causes PCM to underestimate airflow)

Vehicle running out of fuel or engine oil dip stick not seated.

From the chilton manual.Hope this helps

 

[killj0y]

When did the problem start and what did you "fix" right before it started?

 

[meastt]

Thanks for the info so far.

If this helps, the vehicle feels very sluggish at low end acceleration, like it's starvin for air or fuel.

I just replaced fuel filter with no change and I also hooked up a fuel pressure gauge and it read at 34 psi at idle. Any ideas??

Killjoy,
I bought the truck cash off of craigslist just a couple weeks ago. It wasn't till I took it to the emissions guy that I learned my CEL was burned out. I went home and replaced the bulb and that CEL has been starring me down ever since....

Originally it had p0171 and another code for my EVAP system. I replaced the EVAP purge sensor and that code cleared. Now I'm stuck with the p0171

 

[Bryan22]

... dunno if you missed my post or what, but check the plugs out to see if it's really running lean.

 

[meastt]

I didn't miss your post, In the last 2 weeks I have replaced the plugs, wires and the before cat o2

 

[Bryan22]

ok, so when you changed the plugs what did they look like?

 

[Bryan22]

http://www.atvriders.com/articles/sparkplug.html

 

[meastt]

Bryan22,

Thanks for the link, I wasnt sure what you were asking but with that.....

They were the Overheated type for sure

 

[Bryan22]

then keep searching for a source of unmetered air entering the cumbustion chamber. i'm sorry I can't be more particular. Also what does fuel pressure look like when you open the throttle? andwhat does the fuel pressure do when you dissconnect the vacuum line from the fuel pressure regulator? 34 at idle with FPR connected sounds right. Just want to know what else is going on.

 

[killj0y]

damn you could try getting the vacuum system smoked to find a leak, so you can at least eliminate that completely.

 

[meastt]

Bryan,

Well, when I used the fuel pressure gauge at AZ I didn't hook up the vacuum line to anything, I just ran the guage straight to the fuel rail shredder valve and that's it (honestly it's because I didn't know to hook the vacuum line to the FPR)

Soooo, I will be heading back to check fuel pressure with the vacuum line attached to the FPR and this time I will also record the changes when giving throttle a boost and I'll report back.... Thanks for the info so far it's been a help.

Killjoy,

I have been asking around and I haven't found anyone with a smoke machine but I think that would help