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Diagnostic Code P1131


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#1
crapdog

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My car is a 1997 mazda 626 with a 2.0L 4 cylinder engine, AT and will not idle however it runs smooth above 1000 RPM. The diagnostic test shows a P1131 code. I changed the #1 (fwd) O2 sensor. No help. I cleared the code and it still comes back with P1131. Any suggestions?

#2
Chthonian

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My car is a 1997 mazda 626 with a 2.0L 4 cylinder engine, AT and will not idle however it runs smooth above 1000 RPM. The diagnostic test shows a P1131 code. I changed the #1 (fwd) O2 sensor. No help. I cleared the code and it still comes back with P1131. Any suggestions?

find out what that code means

#3
crapdog

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P1131-HO2S 11 Indicates Lean

#4
Chthonian

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P1131-HO2S 11 Indicates Lean

check your MAF and possibly clean it... check for an intake leak between the MAF and throttle body.. if that doesn't work, change the other O2 sensor

#5
jpit

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P1131-HO2S 11 Indicates Lean

check your MAF and possibly clean it... check for an intake leak between the MAF and throttle body.. if that doesn't work, change the other O2 sensor

Ditto....

#6
crapdog

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Checked and cleaned MAP sensor and idle air valve. No help. During low engine speed there is a loud sound from the valves however it stops at 3250 rpm and above and runs good at high rpm. I checked the timing and its way off. When it is able to idle the timing is off the scale to the left. Could it be a sensor that changes the timing or has the timing belt sliped?

#7
jpit

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Your idle speed and your timing are both inter-dependent, meaning as one changes so does the other. Make sure that you are checking your timing with the car idling at 700 rpm even if you have to hold it there by rotating your throttle plate using your hand.
The timing should be 12 degrees BTDC which is quite aways toward the left.

And from your description it does sound like your timing is off. Maybe the tensioner spring is broken. Think there is a tech bulletin on it.

On another note, my car had similar traits when the mass airflow sensor was dirty.
Also make sure no extraneous air is entering your throttlebody such as a cracked hose between the air filter and your throttlebody like Chthonian said.

#8
snailman153624

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Since you can hear valve noise, maybe your intake manifold bolts and/or gasket are loose.




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