JB4 boost readings still seem low

[Tonkabob]

I finally got around to comparing JB4 boost to Torque OBD app boost. Did 2 back to back runs from the same location, same starting IAT, 0-100. JB4 "ECU boost" shows 1 to 1.5 lower than Torque ECU boost and JB4 "Boost" shows 1.5 - 2 lower than Torque ECU boost. (using Map 0) Can't guarantee the Torque app is correct since I don't have a gauge but weird they both read ECU boost so differently.
So 3rd gear Torque app show 19 PSI and 3rd Gear Jb4 Boost is 17 PSI. Also on latest firmware with the higher boost readings. (last 2 graphs are the same run just showing each JB4 boost separately)

 

[xot1]

I wonder why the values are different.
Is the data source different in the two systems?

 

[Satansfist]

I wonder why the values are different.
Is the data source different in the two systems?

My first thought aswell, maybe taking the boost pressure from different sources/places in the tract or running the same data through different algorithms to come up with the results?

 

[Terry@BMS]

Biggest variable is probably going to be the zero point (e.g. ambient pressure), whether it's being computed dynamically like the JB4 or a pressure gauge would work or static like many logging apps use.

 

[xot1]

I got a boost gauge (input tapped on the MAP sensor) installed yesterday and did a very quick test:

Peak boost 20psi in the log:


Peak boost 23 psi on the gauge:

Now debating about which one is the true boost figure is not of great interest for me, since the number itself doesn't mean much, but I confirm a discrepency in readings.

 

[Terry@BMS]

That's always the rub with these things, what is more accurate? I bet if you attached a mechanical gauge side by side you'd get a 3rd different reading. All we can do is set the JB4 off the spec sheet of the sensor and average deviation feedback provided by customers.

Email me and I'll send an update with it re-scaled up 10% for you to compare with.

 

[GRN D3MÖN 22]

Yeah I too can confirm lower jb4 app boost readings than the torque app. Torque said I do 15psi on stock boost and have hit up to 22psi on map 3 but usually about 21.3psi on 93oct. No big deal as I run the jb4 obd wire more often than the torque app. But I noticed it comparing the torque Dyno to a real one I did a while back.

 

[Tonkabob]

Doing 2 or 3 torque boost logs then 2 or 3 jb4 from the same spot and same iat is probably the best test. Peak can be a spike and the jb4 boost seems to smooth those out a bit.
I did the above test and found jb4 to be about 1.5-2 low. But would be good to have more tests. Maybe easier for me to test since i can run 20 psi without the jb4 plugged in and difference would be larger at 20 than 14. But another 10% bump may be good to keep everyone on the same page.
But looking at xot1s vid it did hold 23 psi. Nice!
Mine may show 25!

 

[Tonkabob]

That's always the rub with these things, what is more accurate? I bet if you attached a mechanical gauge side by side you'd get a 3rd different reading. All we can do is set the JB4 off the spec sheet of the sensor and average deviation feedback provided by customers.

Email me and I'll send an update with it re-scaled up 10% for you to compare with.

I'll test the new firmware vs torque if you send it to me. Always looking for something to test.

 

[xot1]

That's always the rub with these things, what is more accurate? I bet if you attached a mechanical gauge side by side you'd get a 3rd different reading. All we can do is set the JB4 off the spec sheet of the sensor and average deviation feedback provided by customers.

Email me and I'll send an update with it re-scaled up 10% for you to compare with.

Ok I'll send you an email.

Here in the video I have 12.4 of ECU_PSI, I really wonder what the gauge would have shown for the stock peak boost. I should run map 0 to see what it shows.

Did I make a mistake of not buying a mechanical gauge? You make me want to buy one but the wiring now is so clean that I don't want to touch it.

 

[Terry@BMS]

I'll test the new firmware vs torque if you send it to me. Always looking for something to test.

OK sounds good. Let me run it on my car first later today just to ensure it's working and then I'll send it out to both of you.

 

[Terry@BMS]

Ok I'll send you an email.

Here in the video I have 12.4 of ECU_PSI, I really wonder what the gauge would have shown for the stock peak boost. I should run map 0 to see what it shows.

Did I make a mistake of not buying a mechanical gauge? You make me want to buy one but the wiring now is so clean that I don't want to touch it.

No I'm sure it's fine it's just that gauges all read differently and electrical gauges have the additional variable of the "zero" or ambient pressure point to contend with. For that reason when doing calibration I prefer to use high quality mechanical gauges.

 

[xot1]

OK sounds good. Let me run it on my car first later today just to ensure it's working and then I'll send it out to both of you.

Great!

Do you sometimes daily drive the Stinger or does it stay at the office? I think you also got an F90 M5 right?

 

[xot1]

No I'm sure it's fine it's just that gauges all read differently and electrical gauges have the additional variable of the "zero" or ambient pressure point to contend with. For that reason when doing calibration I prefer to use high quality mechanical gauges.

Indeed I can calibrate the offset of my electrical gauge.
Maybe I should hook up a mechanical one ($10 from AliExpress) and see if I have some error margin!

 

[Terry@BMS]

Great!

Do you sometimes daily drive the Stinger or does it stay at the office? I think you also got an F90 M5 right?

I say "my Stinger" but technically it's BMS' Stinger. BMS has around 20 development cars and at any given time different employees are driving them for R&D and testing. Usually at home I keep the Stinger, BMW F90 M5, Audi TTRS, F150 EcoBoost (PS2 turbos, 500whp), and an AMG C63. But on any given day that can change depending on what I need and what other employees here need.

The Stinger is one of my favorite drivers because it's fast, comfortable, and inexpensive enough I don't have to worry about where I park it in crowded LA parking lots. It's already got a couple small door dings and paint chips.

 

[Terry@BMS]

New calibration seems to match up well so I'll leave it in v13 firmware. No crying allowed if someone later determines the JB4 is reading boost too high, lol.

Also remember when comparing manifold boost where most gauges are attached it's PSI2 not PSI.

 

[Tonkabob]

I did 2 like runs logging with jb4 then obd and jb4 "boost 2" was within .2 of obd. I think this looks good.

 

[Terry@BMS]

Good to hear. I'm really loving the new EWG control now that I mostly have it working. That combined with the new boost scaling means we'll probably see some 25psi logs soon lol. Don't think there is much more power to be had beyond "20psi" with the new scaling but never hurts to keep trying.

 

[xot1]

Good to hear. I'm really loving the new EWG control now that I mostly have it working. That combined with the new boost scaling means we'll probably see some 25psi logs soon lol. Don't think there is much more power to be had beyond "20psi" with the new scaling but never hurts to keep trying.

I am so glad to hear this
Any hope to see that for sale before spring?

 

[xot1]

and won't this feature also help with upgraded turbos (e.g. pureturbos)?