2015 BRZ - Rough idle + acceleration struggles

[tomm.brz]

Originally Posted by Compelica

To clarify - does that mean the AFR values would display 11.25 as the lowest value from OBD tools, though stock tunes go richer than that? (10.8 or so I recall).

afr can go to anything, like if you clog someway the intake, or increase the intake tube diameter where maf sits, it will run a lot richer than that
it just means that your current tune has a lambda sensor scaling that only goes as low as 11.25 AFR
I recall Wayno and kodename possibly, they use a scaling that goes to 10.8 or something like that
Personally I scaled it to 10 AFR and I have an extra wideband sensor in my headers to check anytime the real afr

anyway that sensor is broken now so you don t know the afr, it could be 10 or 13.5, it shows 11.25 just only because it s broken and sends a maxed out signal... the afr target map is just a reference

don t drive anymore your car untill you replace the sensor

[Jfheisenberg]

Trying to find the OEM sensor but none of my closer Subaru dealer have in stock. Im gonna have to order it.

Would this be the right part? cant tell if this is the one with the grey connector

https://parts.libertysubaru.com/p/su...2641AA640.html

[x808drifter]

Originally Posted by Jfheisenberg

Trying to find the OEM sensor but none of my closer Subaru dealer have in stock. Im gonna have to order it.

Would this be the right part? cant tell if this is the one with the grey connector

https://parts.libertysubaru.com/p/su...2641AA640.html

Check Toyota too.

[Silvermk2]

Originally Posted by Jfheisenberg

Trying to find the OEM sensor but none of my closer Subaru dealer have in stock. Im gonna have to order it.

Would this be the right part? cant tell if this is the one with the grey connector

https://parts.libertysubaru.com/p/su...2641AA640.html

Why wouldn't you just go to Rockauto and buy the Denso sensor for $95? They make the OEM stuff.

[FR-S2GT86]

Originally Posted by Silvermk2

Why wouldn't you just go to Rockauto and buy the Denso sensor for $95? They make the OEM stuff.

This is why:
https://grassrootsmotorsports.com/ar...t-speed-parts/

[Silvermk2]

You really think Rockauto is flipping counterfeit parts? How do you do know a random internet site is actually shipping you Subaru parts? In my experience Rockauto is usually drop shipping them from the manufacturer. Denso and Aisin make almost everything on most Japanese cars outside of Honda.

[FR-S2GT86]

Originally Posted by Silvermk2

You really think Rockauto is flipping counterfeit parts? How do you do know a random internet site is actually shipping you Subaru parts? In my experience Rockauto is usually drop shipping them from the manufacturer. Denso and Aisin make almost everything on most Japanese cars outside of Honda.

You don't think Denso or any other "OEM" parts can't be counterfeited? I wouldn't want to find out the hard way, so I would rather go to the dealer for the parts and install them myself. That way, I can pull the old one out and compare it to the new one I'm putting in for peace of mind.

And I would NEVER go aftermarket on something as important as a sensor. That's just asking for trouble.

[Jfheisenberg]

Originally Posted by tomm.brz

maf has no problem to me
anyway always good to clean it
your problem is a faulty lambda sensor, maybe you got it damaged , it swings between max and min so you need to replace that

You were spot on! After replacing this sensor (primary O2 / lambda sensor) , all my problems went away. The car is idleing fine, and no longer having the sluggish problem.

The car even sounds better now. I drove like this for about 2+ months and these past few weeks the car started to sound like shxt.

Thank you all that help me figured out this problem, really appreciate it. Fingers cross that i dont get more problems.

[FR-S2GT86]

Glad you got it solved.

The lesson here is that even though there's no CEL or diagnostic code, that doesn't rule out a bad part. Data logging is your friend and should always be used as a tool to help you figure out the problem when your engine seems to be operating incorrectly.

[Jfheisenberg]

Originally Posted by FR-S2GT86

Glad you got it solved.

The lesson here is that even though there's no CEL or diagnostic code, that doesn't rule out a bad part. Data logging is your friend and should always be used as a tool to help you figure out the problem when your engine seems to be operating incorrectly.

Yes, there was no CEL code while i was with the OFT stage 2+ tune. Last December, when i flashed back to OEM tune and took it to the dealer, i got code P219A "Bank 1 air fuel ratio imbalance" Idk what this meant, i thought this was due to my catless header and running with stock tune.

One thing to point out, is that I also contacted OFT support. Their support team mentioned that they 'disable' some codes while on Stage 2+ tune. Im not sure why they do this. I think that if those codes where not disabled, i could have found the problem much faster.

[FR-S2GT86]

Originally Posted by Jfheisenberg

Yes, there was no CEL code while i was with the OFT stage 2+ tune. Last December, when i flashed back to OEM tune and took it to the dealer, i got code P219A "Bank 1 air fuel ratio imbalance" Idk what this meant, i thought this was due to my catless header and running with stock tune.

One thing to point out, is that I also contacted OFT support. Their support team mentioned that they 'disable' some codes while on Stage 2+ tune. Im not sure why they do this. I think that if those codes where not disabled, i could have found the problem much faster.

That makes total sense in your case with your catless setup that the OFT flash would have disabled that code from triggering a CEL, and should be something that users of the product should probably be made aware of before using the product (if they aren't informed somewhere already). I've got the rear O2 sensor failure related codes disabled in my flex-fuel tune through EcuTek. Sometimes in order to make a gain somewhere, you may have to make sacrifice somewhere else and we have to live with that and adjust to it as best we can.

It's threads like this though that help us all learn how to overcome issues that crop up when using aftermarket tunes. I'm glad you were able to get back with us with the final verdict. And glad your twin is back on the road playing nice.