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Terry @ BMS Terry @ BMS is offline
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Default MB JB4 Logging Parameters - 03-25-2020, 03:13 PM

Hey guys,

We’ll use this thread for details and discussions on MB specific JB4 logging parameters and discussion.

Boost: Pressure in front of the throttle body in PSI. Normal range from the factory is 12-14psi depending on barometric pressure, intake temperatures, engine speed, time under boost, and other factors. Boost will increase under JB4 maps and expect to see a normal range of 16-20psi depending on the map selected. Note when reading boost short term “spikes”, especially against a closed throttle body, are not relevant. Look for sustained boost during longer pulls for a more accurate reading of what your boost pressure is. If boost exceeds the boost safety setting on the user adjustment page the JB4 will disable. Remember with this platform boost targeting is LOAD based which means at lower elevation, colder temperatures, you'll have a LOWER boost target than higher elevation, warmer temperatures. The factory logic attempts to adjust it's boost target to keep engine performance similar across a wide range of operating conditions.

Boost2: Pressure behind the throttle body in the intake manifold. This is generally a “better” indication of how much boost the engine is actually under. Normally Boost2 will mirror Boost unless the throttle blade is closing enough to limit manifold boost.

Target: This is how much boost over factory the JB4 is requesting. It will vary by JB4 map, running conditions, engine speed, throttle position, and a host of other internal tuning factors. Generally map2 runs around 6psi over factory peak tapering down to 4psi over factory at higher engine speed.

ECU_PSI: This is how much boost the ECU is observing and will generally mirror factory boost levels. At high enough boost levels Boost – Target = ECU_PSI.

DME_BT: This would represent how much boost the ECU is requesting at an given moment but is not enabled on the Kia platform yet.

Pedal: How far down the gas pedal is being pushed 0-100%

Thrtl: The position of the throttle body 0-100%. This value is run by the ECU and it’s important to realize that the throttle body itself is substantially over sized, meaning that there needs to be significant throttle movement before you’ll see any deviation between Boost and Boost2. The ECU generally uses throttle to regulate ECU_PSI to DME_BT, closing throttle when ECU_PSI exceeds DME_BT, which can happen for a variety of reasons. Most commonly a dynamic target change due to traction control or some other on ECU driven on demand target change. On cars with fully modified exhaust systems you might see boost creep over target in higher gears and when that happens you’ll see throttle close proportionally to maintain Boost2 on target.

WGDC: The position of the wastegate actuator 0-100%. This parameter is not enabled yet..

Ign1: Timing advance currnetly only able to log cylinder 1. As you start to approach a limit of Boost for a given fuel quality/octane level then you’ll start to see ~3.5 degree timing drops in specific cylinders. The lower the grade fuel the more frequently you’ll see drops. If you see drops in the same cylinder repeating several times in a single gear then it’s usually an indicator that you’d be better off with a lower Target for the given fuel. Note that timing in all cylinders regularly drops negative during shifts and under some other driving conditions so do not confused mapped changes affecting all cylinders with cylinder specific timing drops when evaluating logs. Cyl 2-6 are not available for all vehicle models.

Ign Avg: This is not enabled for the MB platform yet.

AFR: Air/fuel ratio bank1. Factory air/fuel ratio runs stoich 14.7:1 during lean spool mode and quickly drops down to 10:1 under sustained full throttle. The JB4 using FuelEn will lean out the AFR dynamically to a target of around 11.9:1. If AFR goes leaner than 14:1 at higher RPM the JB4 will disable.

AFR2: Same as above but for bank2. Note 4 cylinder vehicles will have only one bank and AFR2/Trim2 will always show as 0.

Trim: Fuel trims in bank1. The JB4 has scaled fuel trims for quicker viewing, 25 in JB4 logs = 0%, 50 = +34%, and 0 = -34%. Generally fuel trims will jump up in to the 40s under peak torque and drop down towards 25 at higher RPM.

Trim2: Fuel trims in bank2. These will mirror Trim generally and if there is a deviation may indicate a fuel wire is loose or installed improperly. The JB4 will disable if Trim and Trim2 have more than a 15pt variation.

FuelEn: This represents the bank1 dynamic o2 sensor offset required to maintain a 11.9:1 AFR at full throttle. It’s managed by the JB4 internally using its dynamic double fuel control PID.

CalcTQ: This represents the bank2 equivalent of FuelEn.

Gear: This is not currently enabled for MB

MPH: The road speed in miles per hour. Since we don't have gear yet "boost by gear" is actually based on road speed. 1st gear is up to 34mph, 2nd gear is up to 53mph, and 3rd gear is up to 83mph.

FP_H: The fuel pressure in mbar of the high pressure pump. Generally will sit above 10. If FP_H dips this indicates you’re using more fuel than the high pressure system can maintain, generally comes up on those running heavy E85 mixtures at higher boost levels. If FP_H drops below 7 the JB4 will disable.

FP_L: Not currently enabled for Kia via CANbus, some customers have this linked up to Fuel-IT low pressure analog sensors they’ve added on. If you have not added on a separate low fuel pressure sensor ignore this parameter.

E85: The ethanol mixture. Generally only accurate if also equipped with a Fuel-IT flex fuel sensor. There is a BETA version of a virtual flex fuel logic in the latest firmware but it’s not fully accurate and only there for data collection.

Meth: If equipped with a WMI kit this represents your meth flow 0-100%.

WaterF: Engine water temperature

OilF: Not yet supported

TransTemp: Not yet supported

Clock: This is used for internal communication diagnostics and generally represents how many samples per second of CANbus data are being returned from the ECU. Not relevant to most users unless diagnosing a CANbus communications issue.

Burger Motorsports
Home of the JB4 the worlds most popular turbocharged tuning system!

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