4 cylinder Camry with P0171 code

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Old 23 Feb 2010, 10:16 am   #1 (permalink)
Jimmy
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Default 4 cylinder Camry with P0171 code

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
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Old 23 Feb 2010, 11:42 am   #2 (permalink)
C. E. White
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Default Re: 4 cylinder Camry with P0171 code

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@mailinator.com> wrote in message
news:ae88fe4f-99ea-4c02-b222-174d82086ec8@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



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Old 23 Feb 2010, 06:08 pm   #3 (permalink)
ycleptor2@cs.com
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Default Re: 4 cylinder Camry with P0171 code

On Feb 23, 11:16*am, Jimmy <JimmyGeldb...@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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Old 09 Apr 2010, 11:14 am   #4 (permalink)
Jimmy
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Default Re: 4 cylinder Camry with P0171 code

Jimmy <JimmyGeldb...@mailinator.com> wrote:
> My 4-cylinder 97Camryis showing a check engine light, and when
> Autozone scanned it, it was showing only a P0171 code (fuel-air
> mixture too lean).


To follow up, I went to a mechanic, who found two air fuel sensor
trouble codes in addition to P0171 (P1130, and another which I don't
have in front of me). He said the aftermarket sensor I installed a
year or two ago was no good, and recommended replacing it with a
Toyota sensor.

Jimmy
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Old 09 Apr 2010, 11:58 am   #5 (permalink)
C. E. White
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Default Re: 4 cylinder Camry with P0171 code


"Jimmy" <JimmyGeldburg@mailinator.com> wrote in message
news:e2ea0467-f7aa-4bec-b118-fdf676bb5ec5@z11g2000yqz.googlegroups.com...
> Jimmy <JimmyGeldb...@mailinator.com> wrote:
>> My 4-cylinder 97Camryis showing a check engine light, and when
>> Autozone scanned it, it was showing only a P0171 code (fuel-air
>> mixture too lean).

>
> To follow up, I went to a mechanic, who found two air fuel sensor
> trouble codes in addition to P0171 (P1130, and another which I don't
> have in front of me). He said the aftermarket sensor I installed a
> year or two ago was no good, and recommended replacing it with a
> Toyota sensor.


You mechanic's advice is very good. I assume you are talking about the
O2 sensors. Toyota uses very good quality and very application
specific sensors. The generic ones are likely to casue problems -
especially if you had to cut and splice wires to use the aftermarket
sensor. I know the OEM sensors seem expensive, but they are worth it.
Try one of the online Toyota parts dealers to get a better price. For
instance try http://tinyurl.com/yaqm9f4 . The front O2 sensor for a
1997 Camry is 130.03 plus shipping. Rock Auto does sell the OE Denso
part for less (90.79 + shipping) and that should be OK as well (just
don't get the generic Denso part, get the one for your application).
Be aware that the sensors are different for California and
non-California models. If you order from a online Toyota supplier, be
sure to provide your VIN. My recommendation is get the actual Toyota
part from an actual Toyota dealer. You might be able to convince a
local dealer to sell you the part for the online dealer price.

Ed


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Old 09 Apr 2010, 01:09 pm   #6 (permalink)
SMS
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Default Re: 4 cylinder Camry with P0171 code

On 09/04/10 9:14 AM, Jimmy wrote:
> Jimmy<JimmyGeldb...@mailinator.com> wrote:
>> My 4-cylinder 97Camryis showing a check engine light, and when
>> Autozone scanned it, it was showing only a P0171 code (fuel-air
>> mixture too lean).

>
> To follow up, I went to a mechanic, who found two air fuel sensor
> trouble codes in addition to P0171 (P1130, and another which I don't
> have in front of me). He said the aftermarket sensor I installed a
> year or two ago was no good, and recommended replacing it with a
> Toyota sensor.


When I had similar problems with a Camry, my mechanic warned me against
the use of after-market sensors. He won't use them. The replacement
sensor is a Denso (Toyota) sensor specific to the vehicle. He said that
the after-market sensors go bad very quickly, if they work at all--it's
not just Toyota trying to sell you OEM parts. Remember to get the
specific sensor for your application, not a "one size fits all."

The sensors are of course ridiculously expensive. My mechanic has a big
box of the bad ones because someone buys them from him for the platinum.

Is it my imagination, or do Toyotas seem to have an abnormally high
level of these sensor failures? Two of our Toyotas have had them fail in
the past year, and my neighbor with a 2005 Highlander just had a failure
(fortunately he talked to me, because his clueless mechanic insisted
that he needed a whole new catalytic converter, which would still not
have fixed the problem of a bad air/fuel ratio sensor). I don't ever
recall one going bad on any other vehicle we've had or that extended
family members have had.
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Old 10 Apr 2010, 03:54 pm   #7 (permalink)
Jimmy
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Default Re: 4 cylinder Camry with P0171 code

"C. E. White" <cewhi...@mindspring.com> wrote:
> "Jimmy" <JimmyGeldb...@mailinator.com> wrote:
> >*He said the aftermarket sensor I installed a
> > year or two ago was no good, and recommended replacing it with a
> > Toyota sensor.

>
> You mechanic's advice is very good. I assume you are talking about the
> O2 sensors.


The mechanic insisted on calling it an air-fuel ratio sensor, not an
O2 sensor. I don't really know if there's a difference in the terms,
but Toyota does refer to the part for California emissions Camrys as
an air-fuel ratio sensor.

> Toyota uses very good quality and very application
> specific sensors. The generic ones are likely to casue problems -
> especially if you had to cut and splice wires to use the aftermarket
> sensor.


The aftermarket sensor I'm replacing said it was an exact replacement
for a 1997 4-cylinder US-built California emissions Camry's air-fuel
sensor.

> Try one of the online Toyota parts dealers to get a better price. For
> instance tryhttp://tinyurl.com/yaqm9f4. The front O2 sensor for a
> 1997 Camry is 130.03 plus shipping.


Thanks. But that link doesn't specify if it's for California
emissions cars or not, and they don't list an air-fuel ratio sensor.

Jimmy
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Old 11 Apr 2010, 04:06 pm   #8 (permalink)
SMS
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Default Re: 4 cylinder Camry with P0171 code

On 10/04/10 1:54 PM, Jimmy wrote:

> Thanks. But that link doesn't specify if it's for California
> emissions cars or not, and they don't list an air-fuel ratio sensor.


In California the front sensor is called an air/fuel ratio sensor, not
an 02 sensor, for whatever reason.

Do not use an after-market sensor. Use a Toyota or Denso sensor that is
specific to your vehicle. The after-market sensors will not work well or
last long, and they are not all that much cheaper anyway.
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Old 16 Apr 2010, 09:33 am   #9 (permalink)
C. E. White
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Default Re: 4 cylinder Camry with P0171 code


"SMS" <scharf.steven@geemail.com> wrote in message
news:4bbf6d49$0$1635$742ec2ed@news.sonic.net...
> On 09/04/10 9:14 AM, Jimmy wrote:
>> Jimmy<JimmyGeldb...@mailinator.com> wrote:
>>> My 4-cylinder 97Camryis showing a check engine light, and when
>>> Autozone scanned it, it was showing only a P0171 code (fuel-air
>>> mixture too lean).

>>
>> To follow up, I went to a mechanic, who found two air fuel sensor
>> trouble codes in addition to P0171 (P1130, and another which I
>> don't
>> have in front of me). He said the aftermarket sensor I installed a
>> year or two ago was no good, and recommended replacing it with a
>> Toyota sensor.

>
> When I had similar problems with a Camry, my mechanic warned me
> against the use of after-market sensors. He won't use them. The
> replacement sensor is a Denso (Toyota) sensor specific to the
> vehicle. He said that the after-market sensors go bad very quickly,
> if they work at all--it's not just Toyota trying to sell you OEM
> parts. Remember to get the specific sensor for your application, not
> a "one size fits all."
>
> The sensors are of course ridiculously expensive. My mechanic has a
> big box of the bad ones because someone buys them from him for the
> platinum.
>
> Is it my imagination, or do Toyotas seem to have an abnormally high
> level of these sensor failures? Two of our Toyotas have had them
> fail in the past year, and my neighbor with a 2005 Highlander just
> had a failure (fortunately he talked to me, because his clueless
> mechanic insisted that he needed a whole new catalytic converter,
> which would still not have fixed the problem of a bad air/fuel ratio
> sensor). I don't ever recall one going bad on any other vehicle
> we've had or that extended family members have had.


I think Toyota tries to very tightly control the AF Ratio to maximize
fuel economy while still meeting emmision requirements. I believe that
this makes the performance of some of their components exceptionally
critical to proper performance.

Ed


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