SUPRA ULTIMATE B58 JB4 GUIDE AND LOG REVIEW (V1)

[SoopraisKing]

@ColonelAdama can you explain the duty bias? And what exactly is the FF setting doing does it tell the wastegate to open to a certain %

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[ColonelAdama]

@ColonelAdama can you explain the duty bias? And what exactly is the FF setting doing

• WGDC: Wastegate duty cycle is most easily explained as “wastegate position offset”. It is essentially the JB4 applying a bias on the wastegate position solenoid to open or close the wastegate as needed to control boost. This is inactive if you don’t have the EWG connection. This parameter is formulated something like this:
  • PID Output = boost_error (boost vs. boost target) * Internal Mapping * PID Gain (see wastegate tuning)
  • WGDC = FF + PID Output
• FF: Short for "feed forward" or the fixed component of the PID boost control system. This is the starting point for boost control and the PID will then adjust WGDC above or below this value as needed for fine tuning. The user adjustment variable FF / wastegate adaptation value (0 -100) scales the FF value and will adjust itself over time as part of the normal JB4 learning routines. In addition, this value can be user adjusted by RPM using the duty bias settings(see wastegate tuning). The default value of FF is 50, but you may see it change across logs. If you don’t want it to adapt, enable Bit 1 under options. Duty bias ("FF by RPM") settings do not adapt.

does it tell the wastegate to open to a certain %

basically yes

 

[ColonelAdama]

Posted some screen shots and it’s on map 6

Try datazap, I can't review photos

 

[Sscanlon]

Thoughts on these two logs? First time, MT running 93 gas with an AA catted downpipe, dinan exhaust, and armaspeed intake. Did 3rd gear starts at 2500 rpm but may have auto logged too long so some other stuff may be after the runs.

https://datazap.me/u/suprasteve/supra-map-1-mt?log=1&data=1-4-9

https://datazap.me/u/suprasteve/supra-map-1-mt?log=1&data=1-4

these are map 1.

I updated (and used for these logs) the latest firmware v24 for the MT changes like you mentioned and everything has felt very smooth so far.

 

[ColonelAdama]

Thoughts on these two logs? First time, MT running 93 gas with an AA catted downpipe, dinan exhaust, and armaspeed intake. Did 3rd gear starts at 2500 rpm but may have auto logged too long so some other stuff may be after the runs.

https://datazap.me/u/suprasteve/supra-map-1-mt?log=1&data=1-4-9

https://datazap.me/u/suprasteve/supra-map-1-mt?log=1&data=1-4

these are map 1.

I updated (and used for these logs) the latest firmware v24 for the MT changes like you mentioned and everything has felt very smooth so far.

Definitely room for improvement. Try FF at 40 and see if throttle clears up. Probably needs slight duty bias changes too, but we'll see after

 

[Sscanlon]

Definitely room for improvement. Try FF at 40 and see if throttle clears up. Probably needs slight duty bias changes too, but we'll see after

Thanks! I lowered to 40 but only had time to quickly test it out so the run wasn’t too clean. A couple gaps along the run cause some wheel spin so I don’t know if this tells you much. I can run a cleaner run tomorrow if this isn’t helpful

https://datazap.me/u/suprasteve/log-1725051729?log=0&data=1-4-9

 

[Eastwood]

Here's @Eastwood 's latest log. Bumpy road so you can see TC kick in a little (timing dip). Or an MT quirk that needs to be worked out... We'll see on a smoother road lol.

https://datazap.me/u/coloneladama/log-1724878009?log=0&data=1-2-4-8-11-20-25-26-27-28&solo=2-4

Perfect timing otherwise at about 18-19psi on 91/E30. Notice how low WGDC has to be on MT cars. Way too high of boost and choppy throttle if any higher.

Here’s my last log, same settings as that log above but on a smoother road.

https://datazap.me/u/2jz404/log-1724969807?log=0&data=1-4

 

[-Golf-Addict-]

Definitely room for improvement. Try FF at 40 and see if throttle clears up. Probably needs slight duty bias changes too, but we'll see after

Dude Colonel, you are a Legend for making this thread and also taking the time! Thank you. I have heard that the JB4 does not work well with MTs. Did this happen to get fixed? I know nothing about cars, tuning, mapping etc… I am afraid I will do something wrong and blow my car up. How do I get started with this?

 

[Eastwood]

Dude Colonel, you are a Legend for making this thread and also taking the time! Thank you. I have heard that the JB4 does not work well with MTs. Did this happen to get fixed? I know nothing about cars, tuning, mapping etc… I am afraid I will do something wrong and blow my car up. How do I get started with this?

Read first post:
https://www.supramkv.com/threads/supra-ultimate-jb4-guide-and-log-review-v1.20544/#post-332240

I know this thread is 38 pages, but I would skim over it. There’s a lot of good stuff in it. Then decide if this is the route you want to go.

 

[-Golf-Addict-]

Read first post:
https://www.supramkv.com/threads/supra-ultimate-jb4-guide-and-log-review-v1.20544/#post-332240

I know this thread is 38 pages, but I would skim over it. There’s a lot of good stuff in it. Then decide if this is the route you want to go.

Yeah I know sorry, after I posted I went and read the whole thing. I think I am gonna do this till I unlock the DME, unless I am happy with what JB4 does. I just don’t know anything about this stuff and afraid I’ll mess my car up

 

[Eastwood]

Yeah I know sorry, after I posted I went and read the whole thing. I think I am gonna do this till I unlock the DME, unless I am happy with what JB4 does. I just don’t know anything about this stuff and afraid I’ll mess my car up

All good, it's a lot to take in. I read through this entire thread and it gave me a better feel.

@ColonelAdama just helped tune my MT Supra on a map 6 and it feels great right now.

 

[-Golf-Addict-]

All good, it's a lot to take in. I read through this entire thread and it gave me a better feel.

@ColonelAdama just helped tune my MT Supra on a map 6 and it feels great right now.

You don’t have any jerkiness? Throttle closures? Some people are saying that it’s not safe to put a piggy back on the car. As someone that has done it do you feel it’s bad?

 

[Sscanlon]

Thanks! I lowered to 40 but only had time to quickly test it out so the run wasn’t too clean. A couple gaps along the run cause some wheel spin so I don’t know if this tells you much. I can run a cleaner run tomorrow if this isn’t helpful

https://datazap.me/u/suprasteve/log-1725051729?log=0&data=1-4-9

got two clean runs at 40 ff ( the logs ended up grouping). Looks like throttle is a bit better?

https://datazap.me/u/suprasteve/log-1725211723?log=0&data=1-4-9&zoom=2-153

 

[AvzSupra]

Hi Guys.
I have a 2020 2 port Supra with JB4, dp, intake and semis.
With map 3 I am getting a 400m time of 12.2 and 60ft of 2.09.
Is this normal?

 

[digimat2566]

This is called a timing correction - any step down from a cylinder ignition advance from the linear climb to redline. (ign1-6 parameters).

just means that the car detects conditions for pre-ignition. Not necessarily knock, but it is how you know you've reached the limit of the octane. some is fine, like in yours. i would imagine going to Map 2 will make it worse.

Today I tested the same fuel with map2, the result is as follows.
https://datazap.me/u/digimat2566/2024-a90-supra-map2-test?log=0&data=1-4

I tried to interpret the logs, there's still something confuses me after a little research.
1. In some data points, only 1 or 2 cylinders experience timing pull, while others are fine. Is this also considered bad?
2. I see big timing correction happend near 7k rpm, after the throttle close, is this negligible?

Thanks.

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