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Discussion Starter · #1 · (Edited)
Per Kraken's request. Special thanks to all the great members here who taught me all of this over the past couple of years! Feel free to suggest corrections or additions to what I have below and I will update as appropriate.

JB4 – Intermediate Log Reading and Parameter Definitions on VR30 platform

How to log – Ideal log would be to utilize manual shifting and start in 3rd gear -low RPM (say 2500 or so). FULL THROTTLE..take the car all the way up to redline, shift to 4th, and stay in full throttle as long as it is still safe.

If posting a graph on this site for advice/guidance, make sure you include the following fields - RPM, Target, Boost, Boost2, Trims, Trims2, AFR, AFR2, Ign1, Throttle, Pedal. State in the body of your post 1. What Map You are Running 2. What Fuel You Are Running (Brand and Octane) 3. Year, Make, Model and Mods of your car if it is not already in your Forum Signature like it should be! 4. Also helpful to know Temp/weather conditions and if you are at unusually high altitude (like Denver).

To post the graph, from your phone, click Logs Tab. Pick the appropriate Log. Choose Graph. Zoom in on the area of the log at the beginning and the end of a proper log (per above). Take a screenshot picture. Attach the screenshot pic to your post.

How to read the logs:

  • Timestamp – Internal JB4 timer in 1/10ths of a second
  • Rpm – Self Explanatory
  • Ecu_psi – This is the boost psi called for by the cars ecu. Redsport values will be higher than non RS. If the car is ECU tuned, this will read the tune amount, not original stock
  • Target – this is the amount JB4 is adding to the ecu psi
  • Boost – this is the actual boost being generated, assuming the turbo is fully spooled, this will equal roughly the ecu plus target
  • Pedal - % Pedal imput
  • Iat – inlet air temp – usually 10-15 degrees warmer than outside atmosphere temps because of engine bay heat
  • Fuelen – this is a measure of the JB4 fuel wires. A value here means that JB4 is working towards leaning out the Air Fuel ratio. JB4 cannot add fuel, only lean it out.
  • Wgdc – This is a measure of wastegate performance based on EWG wires installed and settings. I could use some help explaining these values from other members.
  • Throttle – this is % throttle open – should mirror pedal but traction control, rpm limiter and other nanny’s can pull this value back despite what the pedal is calling for
  • Fp-h – not meaningful on our platform (at least not officially)
  • Ign_1 field – this is measure of timing/spark advance. This is one of the most important fields to monitor. When the car is running healthy, Low in the rpm band, this value is generally high – say low teens – and as you proceed to the mid rpm’s the value will move lower to say mid-single digits and then as you move up towards redline, the value should rise again to low double digits. Sudden drops in this value of say 3 or more indicates that the car is experiencing pre-detonation (knock) and is compensating by pulling timing back. If you see these types of drops or very low values (below say 4) you should adjust your boost target downward. Knock can be very destructive to the engine. The amount of boost you can run is highly dependent on the octane level of your fuel. If you can raise fuel octane, you can run more boost without risking knock. NOTE: Spark Advance resets to zero at each gear shift. This is normal You want to monitor that the advance comes back immediately after and returns to the normal curve based on rpm as discussed above.
  • Calc_torque - not meaningful on our platform (at least not officially)
  • Trims – this is measure of fuel delivery capacity utilization. 44 is the max value. If you see constant values at 44, that means you are our of fuel delivery capacity and risk Air Fuel Ratio going too lean.
  • Dme_bt – not meaningful on our platform (at least not officially)
  • Meth – this is measure of Water Methanol Flow if you have the JB4 WMI kit
  • Fp_l- not meaningful on our platform (at least not officially)
  • AFR – Air Fuel Ratio as measured by your O2 sensors. During turbo spool, you will see this value higher (leaner) 14-16. Once the turbos are spooled, this should decrease to high 10, low 11 if using stock ecu tune, and low 12 if using the JB4 fuel wires. BMS believes the car makes more power at that leaner AFR. Theoretical ideal AFR is mid 14’s according to "science", so you are not pushing limits on the lean side either way.
  • Ff – Wastegate measure “Feed Forward” Could use some help on what this actually means
  • Clock – not meaningful on our platform (at least not officially)
  • Map - Current JB4 Map setting
  • Afr2 – Air Fuel Ratio on bank 2. Should be very close to AFR value
  • Ign_2- Ign_6 – not meaningful on our platform (at least not officially)
  • Oilf – Oil Temperature in Fahrenheit
  • Waterf- Water/Coolant Temp in Fahrenheit
  • Transf – Temperature of the Intercooler Coolant – while this is not charge-air temp, it’s the closest thing we have to help monitor it on JB4
  • E85 – assume this is used in flex-fuel applications? Not sure
  • Boost2 – Actual Boost on bank 2. Should be nearly identical to Boost field
  • Trims2 – Trims on bank 2. Should be very close to Trims field
  • Mph – self explanatory.
 

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Per Kraken's request. Special thanks to all the great members here who taught me all of this over the past couple of years! Feel free to suggest corrections or additions to what I have below and I will update as appropriate.

JB4 – Intermediate Log Reading and Parameter Definitions on VR30 platform

How to log – Ideal log would be to utilize manual shifting and start in 3rd gear -low RPM (say 2500 or so). FULL THROTTLE..take the car all the way up to redline, shift to 4th, and stay in full throttle as long as it is still safe.

How to read the logs:

  • Timestamp – Internal JB4 timer in 1/10ths of a second
  • Rpm – Self Explanatory
  • Ecu_psi – This is the boost psi called for by the cars ecu. Redsport values will be higher than non RS. If the car is ECU tuned, this will read the tune amount, not original stock
  • Target – this is the amount JB4 is adding to the ecu psi
  • Boost – this is the actual boost being generated, assuming the turbo is fully spooled, this will equal roughly the ecu plus target
  • Pedal - % Pedal imput
  • Iat – inlet air temp – usually 10-15 degrees warmer than outside atmosphere temps because of engine bay heat
  • Fuelen – this is a measure of the JB4 fuel wires. A value here means that JB4 is working towards leaning out the Air Fuel ratio. JB4 cannot add fuel, only lean it out.
  • Wgdc – This is a measure of wastegate performance based on EWG wires installed and settings. I could use some help explaining these values from other members.
  • Throttle – this is % throttle open – should mirror pedal but traction control, rpm limiter and other nanny’s can pull this value back despite what the pedal is calling for
  • Fp-h – not meaningful on our platform (at least not officially)
  • Ign_1 field – this is measure of timing/spark advance. This is one of the most important fields to monitor. When the car is running healthy, Low in the rpm band, this value is generally high – say low teens – and as you proceed to the mid rpm’s the value will move lower to say mid-single digits and then as you move up towards redline, the value should rise again to low double digits. Sudden drops in this value of say 3 or more indicates that the car is experiencing pre-detonation (knock) and is compensating by pulling timing back. If you see these types of drops or very low values (below say 4) you should adjust your boost target downward. Knock can be very destructive to the engine. The amount of boost you can run is highly dependent on the octane level of your fuel. If you can raise fuel octane, you can run more boost without risking knock. NOTE: Spark Advance resets to zero at each gear shift. This is normal You want to monitor that the advance comes back immediately after and returns to the normal curve based on rpm as discussed above.
  • Calc_torque - not meaningful on our platform (at least not officially)
  • Trims – this is measure of fuel delivery capacity utilization. 44 is the max value. If you see constant values at 44, that means you are our of fuel delivery capacity and risk Air Fuel Ratio going too lean.
  • Dme_bt – not meaningful on our platform (at least not officially)
  • Meth – this is measure of Water Methanol Flow if you have the JB4 WMI kit
  • Fp_l- not meaningful on our platform (at least not officially)
  • AFR – Air Fuel Ratio as measured by your O2 sensors. During turbo spool, you will see this value higher (leaner) 14-16. Once the turbos are spooled, this should decrease to high 10, low 11 if using stock ecu tune, and low 12 if using the JB4 fuel wires. BMS believes the car makes more power at that leaner AFR. Theoretical ideal AFR is low 13’s according to "science", so you are not pushing limits on the lean side either way.
  • Ff – Wastegate measure “Feed Forward” Could use some help on what this actually means
  • Clock – not meaningful on our platform (at least not officially)
  • Map - Current JB4 Map setting
  • Afr2 – Air Fuel Ratio on bank 2. Should be very close to AFR value
  • Ign_2- Ign_6 – not meaningful on our platform (at least not officially)
  • Oilf – Oil Temperature in Fahrenheit
  • Waterf- Water/Coolant Temp in Fahrenheit
  • Transf – Temperature of the Intercooler Coolant – while this is not charge-air temp, it’s the closest thing we have to help monitor it on JB4
  • E85 – assume this is used in flex-fuel applications? Not sure
  • Boost2 – Actual Boost on bank 2. Should be nearly identical to Boost field
  • Trims2 – Trims on bank 2. Should be very close to Trims field
  • Mph – self explanatory.
Made this a sticky.
 
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Infiniti Q50 Premium 3.0t AWD
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I would add a note about timing pull on gear shifts. The ECU pulls timing that looks really scary before the AT shifts and that might startle people that aren't looking at gear.

Edit: I'm blind
 

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St. Louis, MO
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Discussion Starter · #4 ·
Here is a funny post from the N54 site! I politely responded that it CAN be safe but flexible enough to be dangerous!

Is the Jb4 safe?
Today, 03:19 AM

Hey guys I just purchased my jb4, and I have a stock 2018 Q50 Luxe 3.0t with roughly 86k miles (all highway). I was just wondering how safe is the jb4? I have been running map 6 pushing 8 psi for basically all my rpm ranges and the car seems to be doing great, but I just want to know how safe is it actually from the experts. Please let me know!
 
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