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From: Jimmy on 23 Feb 2010 11:16
My 4-cylinder 97 Camry is showing a check engine light, and when
Autozone scanned it, it was showing only a P0171 code (fuel-air
mixture too lean).

There aren't any other codes, and I haven't noticed any reduced
performance or exhaust leak noise. Nothing looked out of the ordinary
under the hood, except that the Intake Air Temperature sensor on the
air filter box had pulled away by maybe an eighth of an inch.

Several people in various internet forums said to clean or replace the
MAF sensor on 6-cylinder Camrys, but they don't say what to do for 4-
cylinder Camrys which have an MAP sensor instead. Can the MAP sensor
be cleaned? Should it be replaced?

Should I try cleaning out the EGR valve?

Should the fuel filter be replaced? Are there other causes of low
fuel pressure? Autozone sold me a bottle of Gumout fuel cleaner.
Could that help? I don't drive much -- I fill up once a month or
less. Could the fuel cleaner cause problems if I don't use up the
tank of gas quickly enough?

Jimmy
From: C. E. White on 23 Feb 2010 12:42
Speed/ density systems (the ones without a MAF sensor) use manifold
pressure, air temperature, engine speed, and throttle position to
estimate air flow and to then inject the appropriate amount of fuel.
They adjust the amount of fuel injected based on the output of the O2
sensors. An intake manifold leak, a bad MAP sensor, a bad throttle
position sensor, a temp sensor, or a bad O2 sensor can all set the
lean F/A code. The Toyota manual will have a procedure for diagnosing
which of these is the casue of the problem. Taking random guesses can
be expensive. If you are determined to do this yourself, you at least
need to look at a manual so you can check the sensors.

Ed

"Jimmy" <JimmyGeldburg(a)mailinator.com> wrote in message
news:ae88fe4f-99ea-4c02-b222-174d82086ec8(a)b18g2000vba.googlegroups.com...
> My 4-cylinder 97 Camry is showing a check engine light, and when
> Autozone scanned it, it was showing only a P0171 code (fuel-air
> mixture too lean).
>
> There aren't any other codes, and I haven't noticed any reduced
> performance or exhaust leak noise. Nothing looked out of the
> ordinary
> under the hood, except that the Intake Air Temperature sensor on the
> air filter box had pulled away by maybe an eighth of an inch.
>
> Several people in various internet forums said to clean or replace
> the
> MAF sensor on 6-cylinder Camrys, but they don't say what to do for
> 4-
> cylinder Camrys which have an MAP sensor instead. Can the MAP
> sensor
> be cleaned? Should it be replaced?
>
> Should I try cleaning out the EGR valve?
>
> Should the fuel filter be replaced? Are there other causes of low
> fuel pressure? Autozone sold me a bottle of Gumout fuel cleaner.
> Could that help? I don't drive much -- I fill up once a month or
> less. Could the fuel cleaner cause problems if I don't use up the
> tank of gas quickly enough?
>
> Jimmy


From: ycleptor2 on 23 Feb 2010 19:08
On Feb 23, 11:16 am, Jimmy <JimmyGeldb...(a)mailinator.com> wrote:
> My 4-cylinder 97 Camry is showing a check engine light, and when
> Autozone scanned it, it was showing only a P0171 code (fuel-air
> mixture too lean).
>
> There aren't any other codes, and I haven't noticed any reduced
> performance or exhaust leak noise.  Nothing looked out of the ordinary
> under the hood, except that the Intake Air Temperature sensor on the
> air filter box had pulled away by maybe an eighth of an inch.
>
> Several people in various internet forums said to clean or replace the
> MAF sensor on 6-cylinder Camrys, but they don't say what to do for 4-
> cylinder Camrys which have an MAP sensor instead.  Can the MAP sensor
> be cleaned?  Should it be replaced?
>
> Should I try cleaning out the EGR valve?
>
> Should the fuel filter be replaced?  Are there other causes of low
> fuel pressure?  Autozone sold me a bottle of Gumout fuel cleaner.
> Could that help?  I don't drive much -- I fill up once a month or
> less.  Could the fuel cleaner cause problems if I don't use up the
> tank of gas quickly enough?
>
> Jimmy

Gumout probably isn't a bad guess, since a blocked injector could lead
to the code.

Search under P0171 in the diagnostics section here:

http://www.camrystuff.com/manuals/Gen4/Diagnostics.pdf

It will give you some idea of how to proceed.

If you're lucky, its a loose hose.
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