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P0171 lean is the only code. Smoke tested, no leaks. Fuel…

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P0171 lean is the only...
P0171 lean is the only code. Smoke tested , no leaks. Fuel pressure is 50 steady key on engine off , and running. I replaced the maf sensor still lean. I reset fuel cell memory and unplugged the oxygen sensors and it ran at 0 ltft and 0 stft .
Submitted: 2 months ago.Category: Chevy
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Customer reply replied 2 months ago
Ltft at 29.69 and stft switching between 3and 10 under load up to 16 24
Answered in 2 hours by:
3/26/2018
Chevy Mechanic: Matt, Engineer replied 2 months ago
Matt
Matt, Engineer
Category: Chevy
Satisfied Customers: 23,204
Experience: Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
Verified

Hello and welcome to Just Answer

there's a couple of things to check :

Incorrect fuelling due to a faulty water temp sensor. If this is the problem then the ECU will be leaving the car constantly ' on choke' and not reducing the fuelling as the engine warms - so unplug the sensor and clean the contacts on both sides with some switch / electrical cleaner (not WD40) and inspect the wiring for any signs of damage to the insulation especially where it runs over other components and through the bulkhead- if this doesn't help consider replacing the sensor as they're not expensive
Check for exhaust leaks before the O2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate.

this can lead to catalyst failure as the extra fuel can re-light inside and melt the catalyst

The best way to find an exhaust leak is to run the engine from cold and feel around the exhaust joints with your bare hands - you'll have about 30 seconds before it all gets too hot and you should feel any escaping gas blowing over your fingers

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Chevy Mechanic: Matt, Engineer replied 2 months ago

My goal is to give you the best advice that I can and I hope that I've helped today. Please remember to rate my service by selecting from the 5 stars at the top of the screen before you leave. If you need more help, use the reply box to let me know.
If you're not pleased, also let me know because rating bad does not result in a refund, there are better options. Rating now will not close this post nor prevent further replies
Thanks Matt

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Customer reply replied 2 months ago
What about dirty injectors , or running e85 ?
Chevy Mechanic: Matt, Engineer replied 2 months ago

Hello

both of those are a possibility

might be worthwhile running a bottle of injector cleaner through the tank

and if that doesn't help then consider removing the injectors and having them flow tested / cleaned

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Chevy Mechanic: Matt, Engineer replied 2 months ago

Hi
do you still need help?
Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! If you're not pleased, also let me know because rating bad does not result in a refund, there are better options. Rating now will not close this post nor prevent further replies
Thanks Matt

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