*SOLVED* Inconsistent power output
 

Hey all, I've tried many things and need help.

2017 BRZ manual performance package 45k miles
Catless plm header, srs over pipe, flex fuel kit

Most of the time the car runs like the symptoms below except maybe every 3 to 4 weeks, it'll run like a f****** dream for about 3 days and then it goes back to running like a disaster.

Symptoms/when the car runs like crap:

No CEL
Sluggish acceleration through out rpm band
Rough first gear start do to less responsive gas pedal
Revs drop noticeably quicker between shifts which makes shifts rough
Car sounds very raspy and louder than normal

When the car runs excellent:

Power and strong acceleration everywhere
(Even with the first engine start I can already tell it'll run great because it revs up stronger when I start it)
Gas pedal very responsive, first gear start like butter
Rev drop normal, smooth shifts
Car sounds clean and healthy, all you hear is the crisp rumble

What I've done:

new MAF
new upstream AF sensor
Checked back pressure for restriction (had a header cat collapse which made the front pipe cat collapse as well but all this was solved since then and the tune was updated for the current header)
Checked exhaust leaks, vacuum leaks

I've ran it on 3 different tunes, which were reviewed by the tuners who said everything's running like it should.

Coincidentally the last time it started running great all of a sudden was after I took out the air filter box to check vacuum leaks, I flipped the filter, put everything back and car ran good but no surprise to me, 3 to 4 days later, it's back to being a mess.
Weather doesn't seem to have and impact because it has ran great/awful in both high 90s and low 40s.

Any specific log would help?

Bubba says to remove the air filter for a few miles and see how it runs.

The results just may lead you to the problem.

:iono:

really sounds like un-metered air is entering the motor somewhere, so the a/f ratio is getting thrown off

haha I appreciate bubba but that doesn't seem safe :eyebulge:

this one is when it runs bad

http://datazap.me/u/stix/2nd-gear-pu...?log=0&data=31

this one is when it runs good

http://datazap.me/u/stix/2nd-gear-pu...?log=0&data=31

And yes vacuum leak was my main concern but I just can't find anything unless I'm missing something very small since there are no codes

I had this same issue on my 2017 86 for nearly a year. I tried all kinds of things, even swapped out the throttle body for an aftermarket one. Then one day about a year ago I installed a K24 into the car and my throttle response has been great ever since. When it's not very responsive feeling, are you able to go full throttle and back to no throttle real quick without the engine revving, as If the pedal isn't registering? Mine would do that. For my car it was as if there was a half second delay on inputs with the pedal.

those every 3-4 weeks you wouldn't happen to be disconnecting your battery, would you

Yes I am able to do that, I think for me it has more to do with the power loss. Glad you got fixed it though

No, definitely not

Are you running low on fuel when this happens? Like below 1/4 tank?

No, it happens at all levels of fuel. E5 or 93 it doesn't matter

Inconsistent power output
 

You need to log correct perimeters. There is not enough info in the logs to tell anything. Not sure if there is going to be anything to see being it is not tripping CEL. These are the funnest types of problems.

Engine Speed (rpm)
Throttle (percent)
MAF Voltage (volts)
Engine Load (g/rev)
Ignition Advance / Total Timing (degrees)
AFR
Commanded AFR
LTFT
Oil Temp
Fuel Sys Status
IAT
IAM Advance Multiplier
FLKC

Ok thanks I'll have these logs ready tonight

new logs

warm idle
http://datazap.me/u/stix/warm-idle?log=0&data=4

normal driving
http://datazap.me/u/stix/normal-driving?log=0&data=4