# Maf in question P0171... It is lazy?



## DAK79 (May 9, 2018)

Hello, Intermittently I get a P0171 code. I checked with a smoke machine and I have no vacuum leaks. My fuel trims are way off to where the car almost will stall out and puff black smoke when idling. I will turn the car off and let it sit for a hour and then restart the car it will run with no issues for a week or two. What should the stock map flow be at idle? My scanner is showing 1.87gr/s at idle or 0.25 Lb/m and at 1500 rpm it will be 3.55 gr/s. Do i have a lazy Maf sensor? The purge valve and pcv seem ok from what I can tell even though GM used tamper proof screws.


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## Blasirl (Mar 31, 2015)

DAK79 said:


> Hello, Intermittently I get a P0171 code. I checked with a smoke machine and I have no vacuum leaks. My fuel trims are way off to where the car almost will stall out and puff black smoke when idling. I will turn the car off and let it sit for a hour and then restart the car it will run with no issues for a week or two. What should the stock map flow be at idle? My scanner is showing 1.87gr/s at idle or 0.25 Lb/m and at 1500 rpm it will be 3.55 gr/s. Do i have a lazy Maf sensor? The purge valve and pcv seem ok from what I can tell even though GM used tamper proof screws.


No idea, but a can of MAF cleaner is cheap.


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## DAK79 (May 9, 2018)

Blasirl said:


> No idea, but a can of MAF cleaner is cheap.


Yeah, I tried that also. The Map numbers given are when the engine runs decent and the fuel trims are close to 1.0 and -3.0.


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## Blasirl (Mar 31, 2015)

DAK79 said:


> Yeah, I tried that also. The Map numbers given are when the engine runs decent and the fuel trims are close to 1.0 and -3.0.


MAF or MAP?


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## jblackburn (Apr 14, 2012)

Check the clip on the air filter and make sure it hasn't backed off the tube. Most common cause of lumpy acceleration and P0171 on a Gen 2.


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## max762 (Apr 27, 2014)

How does that pcv valve come off on a 2018 cruze.


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