BrzEdit - ZA1J700A not hitting set VVT Exhaust Angle
 

Hi everyone!

I finally made the switch over from a ricer (Honda), to a lovely Twin :D
Loving every minute of the RWD, which is so so different and engaging!

Got the car about 6 months now, went for a tune 3 weeks back

ECU: ZA1J700A - JDM, High FD (whatever that means..)
Car: GT 86 Year 2012
Tuner: Rahmat RNR Autosport


Problem: After an extensive tune by Rahmat, he noticed a dip around the 4k rpm region, versus the previous tune from another tuner about 2 years ago.
I asked for that dip to be improved, as it's the exact powerband you are in when exiting Turn 9 (tight left hander, 2nd gear, uphill incline) at Sepang Circuit.

Then we noticed.. hey, the Exhaust VVT is set to 30+ deg for the entire range, but the ECU only sets it to 10 degrees.


Anyone faced a similar issue whereby the VVT Exhaust map is set to a certain target, but the ECU doesn't do what it's told?


If you look at the datalog, the VVT Exhaust curve is.. just like how the 4k dip looks like from factory.

Appreciate if you can point us in the right direction. Could it be like:-
- some torque override map?
- the car not hitting certain conditions, hence the VVT Exhaust doesn't want to play?
- some voodoo shiet?


Considering this is one of the first years of the Twin, i'll be very surprised if the Mapping tables from BRZEdit to the ECU is off / incorrect..

These ECUs should be pretty plentiful in the market granted the age?



One of the few Dynokrafts in KL, Malaysia

http://www.ft86club.com/forums/attac...1&d=1581090536

Dyno chart, after tuning completed. We noticed there was a dip around 4k RPM:-

http://www.ft86club.com/forums/attac...1&d=1581090536



Rahmat's datalog:-

http://www.ft86club.com/forums/attac...1&d=1581090536



VVT Exhaust Table. It all says numbers larger than 10! :-

http://www.ft86club.com/forums/attac...1&d=1581090536

If it's torque dip in 3.5-4K range, then it's there on all twins with stock headers (though with some aftermarket headers too). For most that track their cars it isn't much of an issue as most commonly most drive on track in powerband above it, 4K-redline. For many daily driving it's not that big of a deal either, as when one drives with traffic flow in economic fashion, rpms often are below that dip. This dip on twins related forums is often referred same way as you did, as "torque dip". You can search for many dyno charts in this or other related to twins forums.
Tune cannot do much about it, except tuning very aggressive timings there and less around, but that doesn't sound right to me.
"Way to fix" is aftermarket header that fixes/fills it .. most UEL aftermarket headers do such, and some EL headers too, eg. Ace headers. They fix/fill dip even without tune, but tune is very advisable, due for most gains most getting uncatted headers, so with tune not only getting full gains from upgraded header, but also to disable catalisator readiness checks, to not throw CEL.
I suggest to not care much about it if you don't want to spend extra on header. Imho this characteristic torque dip of these engines is a bit overstated. I took notice of it only when i read mention of it in forums. It never really bothered me in daily driving or on track. Use gearbox to keep engine in powerband, more involvement feel :).
I also find a bit funny, that on hondas with similar torque curve owners often refer with pride "VTEC power kicked in, yo", but for twins it's "dreaded torque dip", lol. It's not that engine has no power/torque in dip area at all and doesn't accelerate through, just that more torque before/after, usually hit if one is lazy to upshift on highway and just floors from low rpm, not so much during steady economical driving or on track, as i mentioned above. If dip still bothers .. get aftermarket header that fixes it.

you posted only one of two tables that command VVT exhaust
i do not know how it s called the other table in brzedit, since this one is called [Normal], make sure also the other table is set the same

As rom brz said make sure yo alter both intake and both exhaist cam tables that are used during normal runnig. There is actually three cam tavles for intake and three for exhaust. One set used in limp or vvt off mode and the other two used in normal motion mode, usually one at low IAM and one at high iam, sometimes called low detonation and high detonation. Both those tables should be set same values.


Also 700A is very old rom you could use the updated A01A or A02A or even the euro rom A01G or A02G

Thanks everyone for the responses!
Really appreciate them.. here are more questions


Haha pardon me for not clarifying;
the car has catless EL headers (Rasty copy)
a resonator in the mid
a magnaflow rear muffler

I'm not chasing for a flat 4k rpm that is best settled with a UEL header, just chasing back for the torque that was possible in the previous tune (do refer to the dyno chart).. That's all :D

Here are pics of what's on the car:-

http://www.ft86club.com/forums/attac...1&d=1581174642

http://www.ft86club.com/forums/attac...1&d=1581174642





http://www.ft86club.com/forums/attac...1&d=1581174642

Ahhh, do you mean this?

And from the small Preview thumbnails, it's quite obvious that the 3 maps are Different (possibly tuner hasn't copied them over).

Are you sure that if they are all 100% the same, then only it takes effect?



Apologies, is there are thread already present on this?

Can you kindly guide me on:-
- where to download a base A02A

- steps to load this new A02A
--- what does my Tuner do?
--- does he "copy" my existing tune onto the A02A?

--- or do we load the base A02A, and retune all over again?



Apologies, my limited experience has only been on Emanage Blue + Hondata before.. First time on OBD2-based tuning


Thanks again!

yes, safe and normal should be set the same... base is not really important as it s actually basically never used.. set safe and normal the same and you won t have the problem again

Ddo what tom said with cam tables


Brzedit should have the base rom ie stock files for A02A or A02G in the stock rom list or you can dowliad them from epifan ie creator of brzedit. Then tuner will need to copy tune into the new base rom

Thank you, will try both suggestions!

Will book the tuner again this week; it is his birthday so didn't wanna bother him yet


Stevw99, May I ask, how do we know what is in the updated ROMs?

For example, my car is a 2012 GT86, so it's got the first gen coil packs, first gen valve springs etc

Is the A02G specific to this 2012 model, or it's more related to the say 2017 FL or newer?

Sorry for the noob questions :D

700x roms were early 2012 roms there was some sactory updates A00x ,A01x and A02x


These were updates for rough idle, cam position sensor issues and high rpm gear change knock reduction transient retard that was damaging DI seals on injectors.


A02x is the highest revision you can run in your pre 2014 car


In your case A02A but A01A is fine as well

Thank you thank you for the great explanation

Will come back with results hopefully in a week!

Thanks steve99 and tomm.brz!

Rahmat the Tuner updated the base map to 02A as per advise, and then copied the previous tables over.

He also noted that for my particular ECU.. after saving the Map, it helped if he closed the entire BrzEdit program..
Then reopen the Program + Map, and then upload it into the Car / ECU.

Worked well indeed, and the Ign Timing is now taking effect :D
The dip around the 4k to 5k rpm has been fixed..
.. and finally hit my target whp with the injen airbox :D


http://www.ft86club.com/forums/attac...1&d=1583768807


http://www.ft86club.com/forums/attac...1&d=1583768807





I think we can close this thread now.. thanks all again for the help! :wub::wub::wub: