Installed prl cobra race maf. Installed tsp race tune. Trims and misfire. Help please?

[Bozo8823]

I installed the prl cobra cold air intake race maf in my 2018 si. I flashed the ecu with the race tune file two step performance sent me when I purchased my ktuner from them last April.
All the hoses are tight, maf sensor is clean (I sprayed it this afternoon 5-18-20.) I disconcerted the battery and reset the ecu.
My long term trims are at -16, short term jump around from 7 to -25.
I have misfires in cylinder 2 and4 but no check engine light.1 and 3 randomly misfire also but not as often as 2 and 4. I did 3 separate 2nd to 3rd gear pulls but no misfire going from 2500 rpm to redline
My AFR fluctuates from 10 to 18, but sit pretty close to 14.9 during idle and low throttle cruising.
I’m very amateur when it comes to tuning, I probably should have let a professional handle it, but I needed to feel like I accomplished something lol.
Any insight would be tremendously appreciated seeing as this is my daily driver and don’t want to ruin my engine.
I have multiple data logs I can email upon request.

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[Bozo8823]

88 views and NO opinions. Lmao. ThAnKs GuYs!!! ?

 

[dark_knight097]

88 views and NO opinions. Lmao. ThAnKs GuYs!!! ?

A lot of people here are mostly lurkers and like yourself, they're new to this and don't know much. So they mostly just prowl through threads to learn.

This is kind of the deal with canned/premade tunes. There are so many variables that can affect your car. Ambient air temps, elevation, humidity, and fuel quality to name a few. They make these tunes to work with as many different vehicles in different conditions as possible. As such, it will not be perfect for all who use it.

Before my custom tune, on ktuner basemaps, I would see LTFT anywhere from -5 to -15. Some days it would be lower, others it would be high. Nothing was wrong with the car. Mine just had a tendency to trend high. I'd recommend trying a different gas station's premium fuel next time you fill up just incase your usual spot got a bad batch.

AFR will never perfectly sit at 14.7 on a canned tune. Fluctuations are normal when you change the position of the throttle. And it's most notable right after you left off the throttle completely. But sitting at/around 14.7-.9 at idle and crusing sounds about right.

About the misfires, check your spark plugs just to be sure. But If you aren't experiencing sluggish acceleration, power breaking up under acceleration, no check engine light(misfire codes), or at least can audibly hear any misfires I wouldn't worry too much about it.
The misfire detection is pretty sensitive on these cars. When taking some datalogs I've seen close to 100 before. I changed all my spark plugs out just to be on the safe side but it didnt change the amount of misfires I would see. Those higher numbers are also mostly due to the lighter flywheel I have.

If you still are not comfortable with the way its operating, email TSP directly and ask If they can look at a datalog to make sure it's running correctly.

 

[fenix-silver]

MAF sensor installed facing the proper direction?

 

[boibuddha]

Maybe you were sent a normal MAF housing instead of the race MAF.
Take a look at the MAF, on the right side it should say: Si with an R underneath if it is the race MAF.

This example is for the non-Si but gives you an idea of where to look.

 

[Bozo8823]

I was told by Corey at tsp that maybe I have a small leak between the maf sensor and the engine. I’ll double check to see if I have the correct maf housing. I’m 90 percent sure it’s correct and the maf sensor is indeed facing the correct direction. Next step is to get some smoke and see if I can find the leak. Thanks for the input, it’s much appreciated.

 

[10thgenSIcoupeBLK]

Shoot now you guys got me wondering if my maf is facing the right way lmao

 

[Jaak_b]

Hey OP I know it’s been a year but was your issue solved?

 

[Bozo8823]

Hey OP I know it’s been a year but was your issue solved?

I left it alone cause Corey from two step said my logs were fine. Just today i flashed my car with the 1 plus tune and my long term fuel trim went from -12 to -6. Car feels great. I am no longer concerned with the fuel trims.

 

[KTunedtoStock]

I left it alone cause Corey from two step said my logs were fine. Just today i flashed my car with the 1 plus tune and my long term fuel trim went from -12 to -6. Car feels great. I am no longer concerned with the fuel trims.

I'll see high negative trims when I let it idle for long periods. Turning it off when you leave the car helps keep my trims close to 0

 

[Bozo8823]

I'll see high negative trims when I let it idle for long periods. Turning it off when you leave the car helps keep my trims close to 0

With the new tsp1plis tune my trims are great. Short term near zero cruising and long term goes between -3 to -7.

Update: Today my long term and short term were zero most of the time. Perfect.

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