Just another P0171 - Toyota Celica Forum
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post #1 of 5 (permalink) Old 01-21-2020, 03:34 PM Thread Starter
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Unhappy Just another P0171

Hi everyone,

My Celica shows the DTC: P0171 System Too Lean (Bank 1).

What i've done so far:

Replaced MAF by Denso DMA-0108
Replaced both heated O2 sensors, by Denso DOX-0273 and DOX-0274
Replaced fuel pump by Denso DFP-0103 and toyota spare part fuel filter and o'rings.
Replaced intake manifold gasket by toyota spare part

The light only turns on, when the car is idle, the car runs normal.

Short fuel trim shows 25%, several ECU resets, no leaks on vacuum line i did smoke tests etc...


Any suggestion? Or should i give up...


Thank you!

_
LuĂ s Almeida is offline  
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post #2 of 5 (permalink) Old 02-02-2020, 01:35 PM
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Is it a GT or GTS? Mileage? The P0171 may be stuck in the ECU and prevent the car passing smog test.

Could be dirty or clogged fuel injectors.

Try a couple bottles of injector cleaner in the fuel tank to see if it's improved.

if not you may have to take the injector out one by one, crank the engine and check the spray patterns. Be careful not spraying fuel near any source of sparks or fire.

Could also be a dirty, stuck and leaky throttle valve. Spray throttle cleaner or may have to take it out and clean.
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post #3 of 5 (permalink) Old 02-03-2020, 05:16 AM Thread Starter
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Thank you for your reply!

It's a Celica GT has a 1zz-fe engine. Has 125k miles.

It's my next step, test the injectors, then the throttle valve.

Once again thank you!

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post #4 of 5 (permalink) Old 02-03-2020, 10:51 AM Thread Starter
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I've got the Toyota Techstream software, there's any test that i can make to track back injectors or throttle problem?

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post #5 of 5 (permalink) Old 02-04-2020, 06:10 PM
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Also check all vacuum hoses to and from the airbox and throttle body.

Make sure they are all hooked up and not cracked or leaky.
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