AFR leaning out after shifting gears

[Toyota John]

I have been having a problem with my car since new. After shifting with low load and RPM below 3000 I get a miss right after I start to accelerate after the shift. I have never driven another frs-brs or a car with throttle by wire so I just blamed it on that and learned how to shift around it by pressing the gas down sooner to miss the miss fire. After I got my ECUTEK cable I started playing with it and logging. I realized it wasn't the throttle by wire but AFR. My AFR was up to 16-17 AFR after every shift and causing a lean miss fire. So I thought not enough accel enrichment. I started adding accel enrichment (transient enrichment in ECUTEK). I noticed that the AFR dropped immediately into the 12's right after I pressed the gas pedal down but still climbed up to the 16-17 before coming back down to the requested AFR. Then I did some reading and though maybe my closed to open loop delay was the problem. So I set them to zero. It is still there, although it seemed to have stopped trims from affecting open loop fueling which was nice. So then I thought maybe it’s the transition from closed loop to open loop making the problem. At the same time started realizing soon after I turn off the delays that I have a MAF scaling problem with a stock intake and filter. So I turned off closed loop by filling my whole fuel table with 12. It got better but still there. It only got better because the lean hump was started at 12 instead of 14.7 so it didn't go up to the point of lean miss fire. My MAF scale is the only thing left I can think of. With high load and high RPM I need to request 12.0 afr to get 12.8 afr. I downloaded the excel spread sheet for MAF scaling so I will try that this weekend. Any ideas from experienced tuners? I don't want to hear anyone say something dump like take your car to a tuner. That's not the point of learning and it’s not helping me.

Here is a pic of a log I did. So you can see the lean hump after accelerating. If you look at RPM you can see a small drop after acceleration which is the lean miss fire. This is from a stop light shifting from 1, 2 and 3 gear.

[Kodename47]

The AFR will rise as you come off throttle as the fuel stops being injected.


Are you logging cylinder # misfire count? If not what makes you think it's lean misfiring?

[stugray]

I would have taken it to the dealer before messing with it.

Are all of the problems you mentioned while using the stock ROM?
If so, what ROM ID?

[Toyota John]

I am not talking about the lift off fuel cut. That is different you can clearly see the flat top on the AFR in the 19-20 range in 2nd-3rd and 3rd-4th. That's the first lean spike with the throttle being lifted off. After I get back on the gas you can see the throttle position rise to about 30% the AFR quickly drops to 12 ish with the accel enrichment then leans out again bumping back up past 16+ before rounding out to about 12 on each shift. I do not trust the dealer in my area to care enough to fix drive ability problems that are so small. I am starting to think that there is something wrong with my car. If no one else has a problem like this than its not normal. The only modifications I have is a agency catless header and mid/crossover pipe. Problem existed before this install when 100% stock.

Oh forgot I have B01C for a base.

[Kodename47]

id you log fuel system status? The AFR can move around a bit in CL if the throttle is changed quickly. Its not helped if the CL MAF scaling is out. What do your trims look like? Adding tip in enrichment may not have helped as the ECU will compensate for very rich conditions and can over shoot.

[Toyota John]

I turned closed loop off by filling in the whole fuel table with 12. It still looked the same. I thought the same thing that closed loop might be fighting my accel enrichment by trying to lean out with trims. I didn't 0 out the range the trims can make changes? But it shouldn't make a difference as I could see short term trims weren't making changes. On WOT pulls my AFR were off farther and farther as I got away from idle. Is it normal to have untuned MAF to be .8 off on afr? Maybe I have an air leak?

[Kodename47]

Have you tried actually logging misfire counts? Why not set the car back to normal CL use and see what happens?


0.8 is about 6% so yes, it's possible.

[steve99]

Originally Posted by Toyota John

I turned closed loop off by filling in the whole fuel table with 12. It still looked the same. I thought the same thing that closed loop might be fighting my accel enrichment by trying to lean out with trims. I didn't 0 out the range the trims can make changes? But it shouldn't make a difference as I could see short term trims weren't making changes. On WOT pulls my AFR were off farther and farther as I got away from idle. Is it normal to have untuned MAF to be .8 off on afr? Maybe I have an air leak?

Agree with kodename47 put all the serrings back to stock, then log

Maf v
Load
Rpm
Stft
Ltft
Afr
Commanded afr

Ect

If you ltft are around 6% that would explain it and if its wildy off then you might have a leak near o2 sensors as you suspect

If you going to scale maf i suggest you use the @vgi utility

See maf scaling thread http://www.ft86club.com/forums/showthread.php?t=64790

[arghx7]

So your car is stock right, hardware wise? Sounds normal to me.

[Toyota John]

My car has a catless header and mid pipe with stock muffler. Everything else is stock. The problem isn't in the changes I made to the tune or the addtion of exhaust parts. It existed on the car when I bought it new. With A01C and now B01C no change. There is either something wrong with my car or I am being more picky then everyone else but I don't think that I am. My friend Dan is coming over tonight after work with his 12 FRS with a cat back on the stock tune and I am going to see if he has the same problem. I didn't get to log this weekend because I was sick. So hopefully I can get to it this week and log the suggested parameters. I am try to talk him into buy a ECUTEK licence so i can log his car and see if his is different.

[arghx7]

Do you have any logs of your car on stock parts with stock tune?

[Toyota John]

Yes but I don't remember which logs they are. It didn't matter because they all looked the same. Nothing I did changed the lean hump after shifting. I drove my friends FRS and his shifted smooth. No signs of the way mine drove or drives like. I talked to my tuning friend Mike Botti. He was unsure of why my car is having these problems and has tuned a bunch of FRS/BRZ and has not seen one with a problem like mine. He has offered to look at it as a favor but unless I make an appointment he is a pretty busy guy it might be a little while being he is in the middle of busy tuning season. I kinda wanted to figure it out on my own anyway. I downloaded the MAF scaling spreed sheet and will try but I don't have high hopes that it will fix this problem. Mike did say that the factory Subaru MAF scaling is almost always way off.

[Kodename47]

Originally Posted by Toyota John

Yes but I don't remember which logs they are. It didn't matter because they all looked the same. Nothing I did changed the lean hump after shifting. I drove my friends FRS and his shifted smooth. No signs of the way mine drove or drives like. I talked to my tuning friend Mike Botti. He was unsure of why my car is having these problems and has tuned a bunch of FRS/BRZ and has not seen one with a problem like mine. He has offered to look at it as a favor but unless I make an appointment he is a pretty busy guy it might be a little while being he is in the middle of busy tuning season. I kinda wanted to figure it out on my own anyway. I downloaded the MAF scaling spreed sheet and will try but I don't have high hopes that it will fix this problem. Mike did say that the factory Subaru MAF scaling is almost always way off.

Why not try the tool that vgi put together? Much quicker than the spreadsheets.

[Toyota John]

I think thats what I have. Its on excel correct?