P219A, P119F - Air Fuel Ratio Imbalance
 

So I've already searched throughout the forum and tried suggestions made by other users, but it's still to no avail.

Vehicle:

• 2017 Subaru BRZ 6M

Prior to Current Situation:

• 1000km on bone stock (no mods), and no CEL
• 500km with Perrin CAI installed, and no CEL

Current Situation:

• Getting P219A and P119F after installing Gruppe-S UEL header. I am on a stock map, no tune.

Current Mods:

• Perrin CAI 2.75"
• Gruppe-S UEL Header

Header Installation:

• new gaskets
• no exhaust leaks after installation

P219A and P119F were showing up on bone stock before I got mods for the car so I brought it into the dealership to fix it and this is what they have done:

• readjusted valve clearance
• replaced o2 sensors

The car is free of any CEL on bone stock after the dealership fixed it

I'm pretty confused as to what's causing these specific codes to come up only after installing the headers. If you guys have ran into similar experience or troubles before please share your expertise. I'm stuck.

Any suggestions or ideas you guys have are more than welcomed and appreciated.

Thanks :party0038:

You need a tune. Aftermarket headers almost all but require one, whether or not they're catted. That'll be the reason why you get an AFR imbalance and code since it deals directly with exhaust flow.

CAIntakes will also alter your AFR though sometimes not to the point of generating engine codes by themselves. Hit and miss at generating codes, but also questionable (if any) gains too.

The two combined is almost certainly what's causing the AFR imbalance, sort of surprised the dealer didn't note them at all..

OFT or Ecutek will get you sorted out.

Thanks for the reply and insight.

As for the CAI, I have done quite a few extensive test drives with nothing but the CAI installed. No CEL. That is why I am pinpointing the culprit of the AFR codes is the header.

To my knowledge, I am supposed to only get a P0420 code for not having a cat in the header and not these AFR codes. But your explanation does make sense. So you're saying that an adjustment in the AFR from a tune can solve this AFR issue?

Yes, a tune will alter a bunch of things way out of my pay grade to optimize your set up for your engine to run more efficiently and smoothly; AFR is just one of the many affected parameters.

As for the CAI, like I said it's hit and miss. It still affects AFR, just that the ECU might not always consider the difference of AFR enough to throw a code by itself.

Those codes are actually "BANK 1 AIR-FUEL RATIO IMBALANCE FOR PORT INJECTION." Maybe there is an issue when the switch is made between PI and DI or one of the injector sets are causing an imbalance.

Normally if the AFRs were an issue then I would expect either:
P0171 System Too Lean (Bank 1)
P0172 System Too Rich (Bank 1)

P0420 is Catalyst System Efficiency Below Threshold (Bank 1).

You have 2 modification that “increase” air flow in and out of the engine. The ECU anticipates a quantity of air at any given time, and adjusts fuel to maintain ideal stoichiometry. More air than it anticipates, it adds fuel to keep up. At a certain point it decides something must be wrong, and throws a code.

Tune it and go from there. Everyone around here says tune it before you even have a header, definitely needs one after.

Question: did you do the valve recall? I'm not sure if it is applicable to the 2017 BRZ/86s, but I've been getting this code post valve recall on my bone stock 2013.

I've called Subaru to check. Mine is not on recall. Are you still facing this issue?

Thanks for the clarifications. I'll go back to my tuner and keep this thread updated.

I sometimes get P0420, which is expected. I've never gotten other codes such as P0171 or P0172. I will talk to my tuner about the injectors and see what he says.

Check you didnt over oil the perrin filter and possibly got oil on maf snsor.


Or you have intake leak, check hoses unde manifold


You shouldnt get those codes just P0420, unless you got other hardware issues

I didn't oil the filter. It's quite new. I also cleaned the MAF with MAF cleaner when I installed it back then.

I did a smoke test in the intake, theres no leak.

What hoses under the manifold are you referring to?

Sent from my SM-G973W using Tapatalk

Seems like this issue happens to stock 2017s?

His car is not stock.

http://www.ft86club.com/forums/showthread.php?t=115951

What about this guy's?

Just a quick update on what I've found out.

I run fine with EL headers, no cel no problem at all. Seems like UEL just does not work with my car.