171 174 lean banks codes still reading

[REDDY]

new o2 sensor fixed the poor gas mileage, hard startup and loss of power

new vent line from tank to filler neck

new throttle positioning sensor

maf sensor was switched

still 171 174 bank 1 and 2 lean codes, cant figure it out.

1 thing i would like to know is how are people telling if the upper intake gaskets need to be replaced, because that could be problem, dont know for sure, even alot of expensive computers cant figure it out

the truck was suppose to be inspected in september, cant till this problem fixed

 

[Turdle]

http://www.explorerforum.com/forums/showthread.php?t=171819&highlight=intake+gasket

 

[REDDY]

ok i get it, i'm just going to have to take it off and look at gaskets and go on judgement.

is it possible a clogged fuel filter, or pinch in fuel line would give those codes since it reads lean, must be too much air sucking in, too lil of gas(clogged fuel filter/line)
or i even heard the computer is compensating from a injector messed up.

 

[2000StreetRod]

Intake cleaner

Some members of this forum check for intake leaks by spraying intake cleaner at possible locations and then noticing if the engine speed temporarily increases. Check all of the vacuum hoses for cracks - especially the one to the IAC valve.

 

[coonerboy]

Some members of this forum check for intake leaks by spraying intake cleaner at possible locations and then noticing if the engine speed temporarily increases. Check all of the vacuum hoses for cracks - especially the one to the IAC valve.

Is there a vacuum hose to the IAC?

 

[REDDY]

sprayed carb cleaner around front of upper intake no idle decrease, but really thats the only place to spray it, the other 2 are unaccessible

no hose to iac

 

[2000StreetRod]

Whoops!

Is there a vacuum hose to the IAC?

No there isn't. I meant the hose that connects the tube that goes from the main intake tube to the IAC valve. There's a right angle hose piece just in front of the IAC valve. When it leaks, it allows unmetered air to pass into the engine resulting in a leaner mixture.

 

[REDDY]

No there isn't. I meant the hose that connects the tube that goes from the main intake tube to the IAC valve. There's a right angle hose piece just in front of the IAC valve. When it leaks, it allows unmetered air to pass into the engine resulting in a leaner mixture.

i didnt know about that piece(didnt check it)

i already ordered upper intake gaskets to be in tomorrow, well hopefully this finally works tomorrow

 

[REDDY]

just trying to pull off the hard egr tube into intake manifold, waiting for friend for 4hands to do this

 

[REDDY]

new gaskets in all back together, runs great, no dummy light.....yet, got to drive it more for the sensors to realign, hopefully now it can get inspected, and that gasket was the problem

 

[REDDY]

:frustrate:scratch:

light still came on


what about valve cover gaskets triggering the codes

 

[Turdle]

Hmm, I don't see how.
Somewhere you still have a vacuum leak happening. I am sure of it. Did you pull the injectors and check the o rings?

 

[REDDY]

i didnt do that, or check fuel pressure yet, about the only things left to do

 

[REDDY]

oh and going to do a compression check i dont knw y its runs fine, but doing that sunday, anyother ideas to check out by then i'm doing it sunday

 

[2000StreetRod]

SOHC or OHV?

Which engine do you have in your Sport?

After changing the intake gaskets and getting no CEL, did you let it idle long enough for the engine to warm up?

Did the CEL come on the second time the engine was started?

OBD-II performs a specific test when certain operating conditions are satisfied. For noncritical test failures, the CEL may not be illuminated unless the failure repeats on two engine/drive cycles. I'll look at the diagnostics to try to determine what conditions result in codes P0171 and P0174.

 

[REDDY]

OHV

takes 2 drive cycles for light to come on

i'd drive it like 20miles let it cool couple hrs, drive again mayb 20miles either that time or next drive cycle light would come on

i went so far as to even examaning the nystate inspection law to find out:
The US Environmental Protection Agency (EPA) guidelines allow up to two monitors
to be in a "not ready" state for model year 1996 through 2000 vehicles and one
monitor "not ready" for 2001 and newer model year vehicles

and to try and find if that 1 trigger is on a monitor that i could get inspected before it was ready....i dont know yet about that either, because either way its got to get fixed

 

[2000StreetRod]

1999 OBD-II Fuel System Monitor

The following is from Ford's 1999 OBD System Operation:

Fuel System Monitor
As fuel system components age or otherwise change over the life of the vehicle, the adaptive fuel strategy learns
deviations from stoichiometry while running in closed loop fuel. These learned corrections are stored in Keep
Alive Memory as long term fuel trim corrections. They may be stored into an 8x10 rpm/load table or they may be
stored as a function of air mass. As components continue to change beyond normal limits or if a malfunction
occurs, the long term fuel trim values will reach a calibratable rich or lean limit where the adaptive fuel strategy is no longer allowed to compensate for additional fuel system changes. Long term fuel trim corrections at their limits, in conjunction with a calibratable deviation in short term fuel trim, indicate a rich or lean fuel system malfunction.

Fuel Monitor Operation:
DTCs0171 Bank 1 Lean, P0174 Bank 2 Lean
P0172 Bank 1 Rich, P0175 Bank 2 Rich
Monitor Execution:continuous while in closed loop fuel
Sensors OK:Fuel Rail Pressure (if available)
Monitoring Duration:2 seconds to register malfunction

Typical fuel monitor entry conditions:
RPM range: idle to 4,000 rpm
Air Mass Range: 0.75 to 8.0 lbs/min

Typical fuel monitor malfunction thresholds:
Lean malfunction: Long Term Fuel Trim > 25%,
Short Term Fuel Trim > 5%

From the above you know that you're entering closed loop or the P0171, P0174 codes would not get set. The source of the lean condition is something that impacts both banks. Since you have replaced one O2 sensor, it is unlikely that you have bad O2 sensors on both banks. I'm not aware of a fuel pressure monitor on any of the Explorers. So as long as the PCM thinks the fuel pump relay is closed and the engine is running that should not be a factor in the test being executed. As you said, you could have low fuel pressure causing a lean condition. Or there could be unmetered air entering the engine but you've already checked for leaks. The MAF sensor could be reading incorrectly but you've swapped it out.

The first thing I would do is to disconnect the battery for long enough to drain the Keep Alive Memory (KAM). This should eliminate Long Term Fuel Trim as a source for the CEL. Then I would reconnect the battery and drive the vehicle twice - each time making sure the engine gets up to operating temperature.

If the same codes get set, then I would borrow or buy a fuel pressure gauge and measure the pressure at the test port. See http://www.explorerforum.com/forums/showthread.php?t=256425 for fuel pressures.

If your fuel pressures all pass, then I would resume looking for intake air leaks.

 

[2000StreetRod]

Another fuel pressure test

If your fuel pressure looks good at idle then increase the engine speed to 2,000 rpm and hold it to see if the pressure drops significantly. If so, you could have a clogged filter or a weak pump that can't keep up the flow rate.

 

[REDDY]

so, i start truck up today light still on, i shut it off for a hour, then start it up..light is off. been driving it around starting it up shuting it off couple times, light still off, wtf

i dont know what to think now, but try and get it inspected on monday if light continues to stay off, it magically went off on it own, hopefully it dont come back on now, but still for it to go off on its own now? wtf?

:EDIT:
Apparently disconnecting the wire harness with that 10mm bolt on it next to the #4cylinder resets computer, cause light came back on, only thought battery and a obd2 machine would do that and not disconnecting a clip.

tomorrow, running all those tests

 

[REDDY]

ok, so.....all the fuel pressures is right, nothing to do with the fuel, it is the air

brand new upper intake manifold gaskets and i sprayed carb cleaner in front and it died down...wtf....i loosened nuts, retorqued to 17ftlbs and the light still came on