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Discuss 95 Crown Vic Rough Idle coding p0171 and p0174 ( lean condition ) in the alt.autos.ford forum at Car Dealer Forums; Hello Ladies and Gentlemen, I have a 1995 Crown Vic LX with 175k miles on ...
  1. #1
    Bob. Wells
    Guest

    Default 95 Crown Vic Rough Idle coding p0171 and p0174 ( lean condition )

    Hello Ladies and Gentlemen,

    I have a 1995 Crown Vic LX with 175k miles on it.

    I first noticed the intermittent problem as a single or double clunk when it
    shifts from 2nd to 3rd and from 3rd to overdrive. I read the engine codes
    and they were P0171 and P0174 which are the lean condition for banks 1 and
    2. Also spit out a P0307 (Cylinder 7 misfire) a few times.

    I replaced the fuel filter as it had been in there quite a while. No change.
    Also had the tranny pan and torque converter dumped and new filter as fluid
    looked to be a pale pink with slight yellow cast. Bottom of tranny pan was
    very clean. Also added Lubegard Red. Not much improvement but thats ok cause
    I wanted to have it changed regardless.

    Found nasty looking thick coolant in plug holes 1 and 3 from previously
    leaking thermostat housing. Cleaned out all plug holes (fair amount of dirt
    in all) and cleaned boots thoroughly. Still throwing the cylinder 7 misfire
    occasionally though. Gently cleaned MAF sensor with Windex spray and blew
    dry. Now the engine runs as smooth as silk most of the time and the tranny
    shifts so smoothly you can't tell except from egine rpm. However a couple of
    times a day it starts running rough again for a few minutes, looses about
    1/3 power and throws both lean codes... and clunks between gears.

    Got a Actron fuel pressure gauge and it was 31 psi engine running and the
    same with engine off and key on. Read it two days later and it was 40 psi
    key on and 31 engine running. Possible bad fuel pump? I have been trying to
    catch it in the rough idle mode and check pressure but have been unable to
    so far.

    My questions would be how long do fuel pumps normally last and is 31 psi
    marginal for running pressure? Since the car is so old and has so many miles
    on it what sensors if any might i look at replacing? Four months ago it
    threw some egr codes for a few weeks but none since. Any other ideas?

    Thank You,
    Bob





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  2. #2
    Sharon Cooke
    Guest

    Default Re: 95 Crown Vic Rough Idle coding p0171 and p0174 ( lean condition)



    Bob. Wells wrote:
    > Hello Ladies and Gentlemen,
    >
    > I have a 1995 Crown Vic LX with 175k miles on it.
    >
    > I first noticed the intermittent problem as a single or double clunk when it
    > shifts from 2nd to 3rd and from 3rd to overdrive. I read the engine codes
    > and they were P0171 and P0174 which are the lean condition for banks 1 and
    > 2. Also spit out a P0307 (Cylinder 7 misfire) a few times.
    >
    > I replaced the fuel filter as it had been in there quite a while. No change.
    > Also had the tranny pan and torque converter dumped and new filter as fluid
    > looked to be a pale pink with slight yellow cast. Bottom of tranny pan was
    > very clean. Also added Lubegard Red. Not much improvement but thats ok cause
    > I wanted to have it changed regardless.
    >
    > Found nasty looking thick coolant in plug holes 1 and 3 from previously
    > leaking thermostat housing. Cleaned out all plug holes (fair amount of dirt
    > in all) and cleaned boots thoroughly. Still throwing the cylinder 7 misfire
    > occasionally though. Gently cleaned MAF sensor with Windex spray and blew
    > dry. Now the engine runs as smooth as silk most of the time and the tranny
    > shifts so smoothly you can't tell except from egine rpm. However a couple of
    > times a day it starts running rough again for a few minutes, looses about
    > 1/3 power and throws both lean codes... and clunks between gears.
    >
    > Got a Actron fuel pressure gauge and it was 31 psi engine running and the
    > same with engine off and key on. Read it two days later and it was 40 psi
    > key on and 31 engine running. Possible bad fuel pump? I have been trying to
    > catch it in the rough idle mode and check pressure but have been unable to
    > so far.
    >
    > My questions would be how long do fuel pumps normally last and is 31 psi
    > marginal for running pressure? Since the car is so old and has so many miles
    > on it what sensors if any might i look at replacing? Four months ago it
    > threw some egr codes for a few weeks but none since. Any other ideas?
    >
    > Thank You,
    > Bob
    >
    >

    35 psi at idle is about normal. If you're getting 40 psi at key on, but
    31 psi at idle, I'd suspect fuel pressure regulator, or possibly a low
    voltage condition to the pump on the Run side. Read the codes after it's
    fully warmed up.


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