BMS VW GTI JB4 info thread

[Handguns4heaRTs]

Help me understand the Max Boost 1st and Max Boost 2nd settings.

I am running Map 6 absolute.
I have left the Max Boost 1st and Max Boost 2nd at the default 0. Does this mean they are just using stock ECU boost in these two gears?


I see from the first post it mentions 17 for first and 19 for second etc.

So I am unsure if I am supposed to leave these at 0 or set them to 17 and 19.

if "you do not want any boost in first you will set the value to .1. If you want only 2psi add over stock you will set it to 2."

Setting to 0.1 will give you stock boost

 

[Chozer]

if "you do not want any boost in first you will set the value to .1. If you want only 2psi add over stock you will set it to 2."

Setting to 0.1 will give you stock boost

That was for additive based not absolute.

Also if left at 0, does that mean it just follows your Map 6 RPM adjustments.

 

[Handguns4heaRTs]

That was for additive based not absolute.

Also if left at 0, does that mean it just follows your Map 6 RPM adjustments.

Ya, now you got ME confused! haha. I would have to assume it's the same.

 

[Chozer]

Ya, now you got ME confused! haha. I would have to assume it's the same.

Haha, well maybe someone will straighten this out for us.
Thanks.

 

[toledospeed]

Haha, well maybe someone will straighten this out for us.
Thanks.

Handguns4heaRTs has additive correct above. For an absolute map 6, simply enter the absolute max PSI you want for 1st and 2nd gear. Example: enter 12.5 and 15.0 for 1st and 2nd respectively. This will limit your absolute map 6 to a max of 12.5 PSI in first gear and a max of 15.0 PSI in second gear. I use the 1st and 2nd gear limits for better traction off the line and it works great. Otherwise leave to 0 (default) and it will use map 6 PSI by RPM.

 

[Gro Harlem]

Then why does BMS have more than one SKU for their JB4 lineup? There's a Group 1, Group 2, Group 3 and so on for the different engines/turbo combinations. Furthermore, if they really are all the same, does this mean I can just bolt on the IS38 with map 2 and be good to go?

Or does it work something like this?
IS20 ECU + IS20 + JB4 = fine
IS38 ECU + IS38 + JB4 = fine
IS20 ECU + IS38 + JB4 = map 6 / further tuning required to compensate for the "mismatch"

It is true the JB4's are all the same model/chipboard and can be swapped between IS12, IS20 and IS38 powered cars.

I got a used Golf R JB4 for my 1.8TSI "Group 3" GSW. The JB4 had the GTI map6 values loaded when I first logged into the BMS app, but I lowered the values to coincide with my 1.8TSI lower boost and it works fine.

If you are putting an IS38 onto a IS20ECU (GTI) then you can simply run the same map you were running, get some logs and then up the boost slowly until the ecu begins to pull ignition timing.

 

[Gro Harlem]

I know I might get torn apart for this but... with a USP cat less Downpipe, will the JB4 correct the CEL or will I need to purchase a spacer?


--2017 MK7 GTI PP Autobahn

The factory ECU will trip the code if you run a catless DP. The ecu will continue to be oblivious to the JB4's existence and will continue to throw codes like it should. You absolutely must run a O2 spacer and hope it tricks the ecu.

 

[gdfraser]

Hi George,

I installed my JB4 upgrade board last night and noticed there were no screws attaching the large connector to the JB1 board when I took it apart. Is this how it is supposed to be or should I be tracking down some screws? I have the Rev 2 unit.

Thanks

 

[George Smooth]

Hi George,

I installed my JB4 upgrade board last night and noticed there were no screws attaching the large connector to the JB1 board when I took it apart. Is this how it is supposed to be or should I be tracking down some screws? I have the Rev 2 unit.

Thanks

I would personally track some screws down. The harness is held in place by the enclosure but I have seen a few that have moved.

 

[gdfraser]

I would personally track some screws down. The harness is held in place by the enclosure but I have seen a few that have moved.

Perfect will do. Thanks for the quick reply... especially on a weekend!!

Cheers


Sent from my iPhone using Tapatalk

 

[rc pete]

Handguns4heaRTs has additive correct above. For an absolute map 6, simply enter the absolute max PSI you want for 1st and 2nd gear. Example: enter 12.5 and 15.0 for 1st and 2nd respectively. This will limit your absolute map 6 to a max of 12.5 PSI in first gear and a max of 15.0 PSI in second gear. I use the 1st and 2nd gear limits for better traction off the line and it works great. Otherwise leave to 0 (default) and it will use map 6 PSI by RPM.

So in 3rd will it go back to the adder map I call it?

 

[toledospeed]

So in 3rd will it go back to the adder map I call it?

Yes, it will go back to the main boost by rpm map 6 for 3rd, unless you also have a boost by gear max set for 3rd gear (most don't).

 

[gdfraser]

The parts came in for my AFR harness. Put this together yesterday and installed my JB4 upgrade. I loved the extra power with the JB1 but the 4 is much smoother!

I have some extra connectors so will make up a couple more harnesses. I'm using gold contacts like the OE one.

Sent from my iPhone using Tapatalk

 

[skian]

The parts came in for my AFR harness. Put this together yesterday and installed my JB4 upgrade. I loved the extra power with the JB1 but the 4 is much smoother!

I have some extra connectors so will make up a couple more harnesses. I'm using gold contacts like the OE one.

Sent from my iPhone using Tapatalk

Nice work. I wish I did the same, but couldn't wait to install the upgrade kit [emoji1]

Sent from my SM-G950U using Tapatalk

 

[Slick99]

The parts came in for my AFR harness. Put this together yesterday and installed my JB4 upgrade. I loved the extra power with the JB1 but the 4 is much smoother!

I have some extra connectors so will make up a couple more harnesses. I'm using gold contacts like the OE one.

Sent from my iPhone using Tapatalk

Is this extra connector for AFR??

Sent from my HTC 10 using Tapatalk