Question on similar obd trouble codes

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Moses - 22 Dec 2008 20:57 GMT

My Taurus has been showing 171 and 174 for a while but now it has
added 1131 and 1151. All of these indicate lean mixture on both
banks. What is the difference?

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Jeff - 22 Dec 2008 23:31 GMT

> My Taurus has been showing 171 and 174 for a while but now it has
> added 1131 and 1151. All of these indicate lean mixture on both
> banks. What is the difference?

One bank is towards the passenger compartment and one is towards the
front of the car.

Jeff

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Mike Hunter - 22 Dec 2008 23:37 GMT

Perhaps he can get some of the bank bailout money to get it fixed? ;)

On Dec 22, 3:57 pm, Moses <awel...@wi.rr.com> wrote:

> My Taurus has been showing 171 and 174 for a while but now it has
> added 1131 and 1151. All of these indicate lean mixture on both
> banks. What is the difference?

One bank is towards the passenger compartment and one is towards the
front of the car.

Jeff

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mechanic@telusplanet.net - 23 Dec 2008 03:27 GMT

P0171 and P0174 indicate that the adaptive fuel strategy has reached a
preset limit... typically, this would be when long term fuel trims have
reached 25% fuel adjustment (rich or lean, though lean is more common than
rich).

P1131 and P1151 indicate that we have moved beyond the fuel systems ability
to cope with the condition and the O2 sensors are no longer switching
rich/lean and are, in fact "trapped" lean.

The P0171/4 are telling us that we are getting into trouble - let's do
something about it - many times with no driveability symptoms. P1131/51 are
telling us that we ARE in trouble and there is every chance that we are
experiencing driveability symptoms.... or soon will.

Compare this to a small child.... P0171 is "I have to go baffroom.". P1131
is "I have to go baffroom" along with foot stamping and breath holding....
If we wait too much longer than this.... it can get less pleasant.

HTH

> My Taurus has been showing 171 and 174 for a while but now it has
> added 1131 and 1151. All of these indicate lean mixture on both
> banks. What is the difference?

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Moses - 23 Dec 2008 14:15 GMT

Good explanation! Yes, I have started to experience driveability
problems including hesitation and missing at idle. But the cause
remains elusive. I'd like to see manifold vacuum a little higher but
don't detect any leaks, The PCM controls are believed to be ok.

On Dec 22, 9:27 pm, <mecha...@telusplanet.net> wrote:

> P0171 and P0174 indicate that the adaptive fuel strategy has reached a
> preset limit... typically, this would be when long term fuel trims have
[quoted text clipped - 21 lines]
>
> - Show quoted text -

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mechanic@telusplanet.net - 24 Dec 2008 01:55 GMT

As I'd said, lean is more prevalent than rich when we see mixture stray from
stoichiometric.... simply because so many things can drive the system lean
while so few can drive it rich...

Some of the simpler things to try would be to inspect the MAF sensor for
contamination, replace the fuel filter (testing fuel pressure while driving
would be a big plus).... making sure that the ignition system is decent ..

Good explanation! Yes, I have started to experience driveability
problems including hesitation and missing at idle. But the cause
remains elusive. I'd like to see manifold vacuum a little higher but
don't detect any leaks, The PCM controls are believed to be ok.

On Dec 22, 9:27 pm, <mecha...@telusplanet.net> wrote:

> P0171 and P0174 indicate that the adaptive fuel strategy has reached a
> preset limit... typically, this would be when long term fuel trims have
[quoted text clipped - 27 lines]
>
> - Show quoted text -

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