P0171 Error 2020 CX-5 Can't find cause

[hhekimyan]

Hello friends.

I have a pretty complicated issue here and I am seeking help.

I have 2020 CX-5 28000 miles with P0171 code, which I can not find the reason.

I checked everything that I would refer to as lean mixture, replaced sensors, and checked air leaks. Everything seems correct, all parameters are within specs, but LTFT is +25 and does not decrease from +20 when the accelerator is pressed, even with WOT. I also noticed that the Fuel Loop would not close and on Live data Closed loop indicates error value, I think it is because the mixture is always lean, but it could be the opposite.

The background if the vehicle was: when I got the vehicle it was dead, the battery leads were mixed. So I replaced a bunch of shorted modules, except PCM, which was already replaced. However, I reprogrammed it and reconfigured it with MDARS, but no result.

At this point I am out of options, but to replace the PCM and reprogram it again.

So friends if you have any suggestions, please advise.

 

[ADS-B]

Check the fuel pump and the fuel injectors.

 

[200955]

You most likely have a vacuum leak of some sort or other. This is mainly a job for a smoke machine but sometimes a spray of brake cleaner at a vacuum connection (via a straw) will reveal the leak by engine increasing in rpm or overall sound. If this is your case this is the cheapest way to detect a leak. Don't forget to clear codes before running the car again. Let us know the outcome.

 

[HyFlyer]

2020 with 28,000 miles ... Wouldn't this be under powertrain 60mo/60k warranty? Have a Mazda dealer fix it?

 

[hhekimyan]

Check the fuel pump and the fuel injectors.

The fuel pressure is constant at 10MP, I thought about injectors, but they react to the disconnect test evenly, so I am not sure that under 28K injectors may have any issue, but the only other way to eliminate injectors is to replace them, as I think there is no objective way to check injectors, unless to connect to the measuring machine. I will check to see if there is someone in the area who can measure them.
Thank you for your input

You most likely have a vacuum leak of some sort or other. This is mainly a job for a smoke machine but sometimes a spray of brake cleaner at a vacuum connection (via a straw) will reveal the leak by engine increasing in rpm or overall sound. If this is your case this is the cheapest way to detect a leak. Don't forget to clear codes before running the car again. Let us know the outcome.

I did the smoke test, and could not find any leak, also sprayed with cleaner, but it did not impact the working phase. I am planning to take off the intake manifold, to examine for a crack.

Thank you, sure I will post the outcome, but if you have any rather ides please share

2020 with 28,000 miles ... Wouldn't this be under powertrain 60mo/60k warranty? Have a Mazda dealer fix it?

Thank you for your reply. I thought about that, but sadly car has a rebuilt title, as I know in that case the warranty is voided, correct me if I am wrong

 

[200955]

I like your approach to the problem and dedication to resolve the issue. At this particular URL
you will view a video that just might help you in resolving your problem: