Bucking on throttle application?

[steve99]

Also log fuel system status see if its switching between cl and ol


Oft v4 have zeroed or reduced the ol\cl timers and fhe ol and cl fuel maps are way different

[QTR FMS]

Originally Posted by Mr_Eyo

This is after about 4 days on this tune:
https://datazap.me/u/protoformx/log-....14&tmax=14.89
AFR is from the stock sensor.

So looks like i'm just shifting at the wrong times and/or with the wrong throttle angle.

i cant see anything from the datalog other than maybe the short fuel trim might too high but not sure if this is your issue,
save your maf scale for a backup and try rescaling your maf using this method you dont need the excel spreedsheet just multiply by percent to your maf scale and see if it gets better if not we will need to look at more stuff, it could be torque calculation issue or something but i dont know any thing about auto trans tuning



[ame]https://www.youtube.com/watch?v=iP4BgKoRvQo[/ame]

[DarkPira7e]

Originally Posted by Tor

Try to log ignition timing. Could be too much transient ignition retard.

When you make the log, do something identifiable after you experience the bucking so it's easy to pinpoint where in the log it happens. E.g. you could go full throttle a few seconds after it happens, conditions permitting. Then it's easy to find in the log.

This was the issue with my tune. I use Tactrix + BRZEdit and found that too transient ing. retard or ramping it up suddenly makes the throttle extremely jumpy. Even cruise control make me look like I was at an Amon Amarth concert

[Mr_Eyo]

Originally Posted by DarkPira7e

This was the issue with my tune. I use Tactrix + BRZEdit and found that too transient ing. retard or ramping it up suddenly makes the throttle extremely jumpy. Even cruise control make me look like I was at an Amon Amarth concert

I think it's this too. You can check the ignition advance in the log I linked in post #4. How much is really needed? How much is too much/unsafe to remove?

The v4.03 Stg 1 transient retard table is not smooth at all; i was thinking about taking a lot of the retard out to help smooth it out.

I tend to shift out of 1st at around 2-2.5k between 0.5 and 0.7 g/rev.

[jflogerzi]

Originally Posted by Mr_Eyo

This is after about 4 days on this tune:
https://datazap.me/u/protoformx/log-....14&tmax=14.89
AFR is from the stock sensor.

So looks like i'm just shifting at the wrong times and/or with the wrong throttle angle.

Am I missing something? That log looks pretty damn good to me...

[Mr_Eyo]

Originally Posted by jflogerzi

Am I missing something? That log looks pretty damn good to me...

Thanks. This was just to show that I don't think it's a bad MAF cal. Reducing low end throttle tip in enrichment in this tune seemed to help with the bucking a bit.

[DarkPira7e]

Originally Posted by Mr_Eyo

I think it's this too. You can check the ignition advance in the log I linked in post #4. How much is really needed? How much is too much/unsafe to remove?

The v4.03 Stg 1 transient retard table is not smooth at all; i was thinking about taking a lot of the retard out to help smooth it out.

I tend to shift out of 1st at around 2-2.5k between 0.5 and 0.7 g/rev.

I'll be honest, I can't really give a good idea what a good amount of advance or retard would be, it's something we played with until it felt right. After seeing that, I can say confidently that in 1st and second, shifting below 4,000 rpm makes the car buck for me regardless of the tune most of the time. Changing how aggressive the throttle input is in the calibration helped with this, but I'm going to be getting a trans and diff mount to see if it helps. I have driven a friend's car that doesn't do it, do I don't think it's my choice in driving style.

[Mr_Eyo]

I captured a log with the bucking while upshifting into 3rd with ignition and port/direct IPWs:
https://datazap.me/u/protoformx/log-...zoom=5108-5162

Observations:
-The bucking is causing my foot to open the throttle a little more in a feedback loop. It shouldn't be enough to trigger tip-in enrichment, but it looks like it is causing the load to wildly vary.
-Fueling mode is CL the whole way.
-The port inject fraction table in this region is either 0%, 25%, or 50%. The log shows flip-flopping between all DI and some PI.
-Looking at the upshift to 2nd immediately prior, there is no injector mode flip-flop during the accel, it's all DI in 2nd. It was PI/DI in 1st.

Possible conclusion: the injector mode toggling is causing the jerkiness. If this is true, what can I do to smooth out the PI fraction table and not impact power or knocking?

[Kodename47]

Originally Posted by Mr_Eyo

The port inject fraction table in this region is either 0%, 25%, or 50%. The log shows flip-flopping between all DI and some PI.

Possible conclusion: the injector mode toggling is causing the jerkiness. If this is true, what can I do to smooth out the PI fraction table and not impact power or knocking?

Check the thresholds on the PI ratio table. Stock it's set to 35% min and 5000rpm IIRC. This means you have either 35%+ or 0% PI up until 5000rpm. Not sure if the OFT changes this. There is a load limit as well, set to 1.5.

[tomm.brz]

i usually use 0.9-1 load limit, 25 or 30% threshold and 3200 rpm, i m good with it

[Mr_Eyo]

Originally Posted by Kodename47

Check the thresholds on the PI ratio table. Stock it's set to 35% min and 5000rpm IIRC. This means you have either 35%+ or 0% PI up until 5000rpm. Not sure if the OFT changes this. There is a load limit as well, set to 1.5.

OFT goes down to 30%. It also has a minimum PI quantity limit of 2.28 -- not sure if this is mL or ms. Looking at my log, it doesn't look like its ms. Looks like I can only go down to 30% in the PI ratio table for non-zero PI? If true, what are the implications of staying DI-only?

[tomm.brz]

try
25%
3200rpm
load 0.9
minimum PI 1.5

i also lower PI scaling from 228 to 224, but not fundamental

[Kodename47]

Originally Posted by Mr_Eyo

OFT goes down to 30%.

Not in the PI table but the PI threshold settings.

[Mr_Eyo]

Originally Posted by Kodename47

Not in the PI table but the PI threshold settings.

I don't see it in the OFT defs.