DATALOGGING

HOW TO DATALOG

When developing a tuning file, datalogging is of utter importance. It is even more important than doing dyno runs. Testing on a dyno and on the road should meet certain conditions. The main limitation of data logging is lack of available channels. However, although there are many preferable channels to log, a few are absolutely necessary.

Always start with a baseline of the complete original car. This is needed to see how the car responds in the normal, OEM condition. If there is a problem within the OEM condition, stop the project and solve the issue before going further.

The channels to log are:

  • engine speed – rpm
  • pedal position
  • engine load
  • throttle body position
  • intake manifold pressure
  • boost pressure request
  • boost pressure actual
  • wastegate duty cycle
  • lambda request
  • lambda actual
  • injection in milligrams
  • injector pulse width
  • rail pressure
  • mass air flow
  • intake air temperature
  • oil temperature
  • water temperature
  • exhaust gas temperature
  • ignition per cylinder
  • ignition adaption (advancement/retarding)
  • knock voltage
  • cam phasing


The best way to show all this data is to store data as excel sheet. See an example below:

 

Engine LoadEngine LoadEngine LoadBoost PressureEngine SpeedEngine LoadBoost PressureBoost PressureEngine SpeedCoolantIntake AirIgnition
CZAS(specified)(spec. corrected)(actual Value)Control (N75)CZAS(G28)(specified)(actual)CZAS(G28)Temperature (G62)Temperature (G42)Timing Angle
%%%%/min%mbarmbar/min*C*C*PGMP
0,0394,792,529,395,70,06108036,1119099001080934827
0,129792,545,196,10,15112048,110809900,09108093485,3
0,2196,295,552,695,30,25108053,4116010000,181080934913,5
0,3197,79454,91000,34112058,614209900,281120934912,8
0,499,29764,71000,43116065,4144010000,37116093496,8
0,5102,398,566,91000,53120066,9147010100,46116093497,5
0,59102,310067,71000,62124068,4149010100,56120093496
0,68104,5101,568,41000,71128069,2152010200,65124093494,5
0,7810610369,21000,81132069,9153010400,75128093485,3
0,87109104,569,91000,9132069,9153010500,84132093485,3
0,96110,5107,570,71001140071,4157010600,93136093485,3
1,06112,8110,471,41001,09140071,4159010701,03140093485,3
1,15115110,472,21001,18144072,2160010801,12140093486,8
1,25116,5113,472,91001,28148072,9163010901,211440934815,8
1,34117,3113,472,91001,37148072,9165011001,311480944815
1,43119,5114,974,41001,46152074,4168011101,41520944815
1,53121,1117,975,21001,56156075,2170011201,51520934715
1,62123,3119,475,21001,65156075,9172011301,591560934712
1,71124,8120,975,91001,75160076,7173011401,681560934715
1,81126,3122,476,71001,84160076,7175011401,781600944612
1,9127,8123,977,41001,93164077,4176011501,871600944612
2129,3125,477,41002,03164078,2177011601,961640934612,8
2,09130,1125,478,21002,12164078,2178011702,061640944612,8
2,18131,6126,978,91002,21168078,9180011802,151680944612,8
2,28133,8128,478,91002,31168079,7182011802,251680934612,8
2,37135,3129,978,91002,4172078,9183011902,341680944512,8
2,46136,8132,879,71002,5172079,7184012002,431720944512
2,56138,3132,880,51002,59176080,5185012002,531720944512
2,65139,8134,380,51002,68176080,5186012102,621760944512
2,75141,4135,881,21002,78180081,2188012102,711760944512
2,84141,4137,3821002,87180082189012202,811800944512
2,93143,6138,882,71002,96184082,7192012302,91840944511,3
3,03145,1140,383,51003,06184083,51930124031840944511,3
3,12146,6141,884,21003,15188085194012503,091880944511,3
3,21148,1143,3851003,25192085,7195012603,181880944511,3
3,31150,4144,886,51003,34192086,5197012703,281920944512
3,4151,1146,386,51003,43196087,2199012803,371920944511,3
3,5151,9147,887,21003,53200088200012903,461960944510,5
3,59152,6147,888,71003,62200088,7200013003,562000944512
3,68153,4149,389,51003,71204090,2200013203,652000944511,3
3,78154,1149,3911003,81204091200013303,752040944511,3
3,87154,9150,7911003,9208091,7199013403,842080954512
3,96156,4150,791,71004212091,7200013503,932080954512
4,06157,1152,292,51004,09216092,5198013704,032120944512,8
4,15157,9153,793,21004,18216093,2197013804,122160954512,8
4,25158,6153,794,71004,28220094,7197014004,212160944510,5
4,34159,4155,295,51004,37224096,2195014104,31220094459,8
4,43160,2155,296,21004,46224096,2194014304,42240944511,3
4,53160,2156,7971004,56228097193014404,5228094458,3
4,62160,9156,7971004,65232097,7194014604,59228094449,8
4,71160,9156,798,51004,75236098,5192014804,682320944410,5
4,81161,7156,71001004,842400100189015104,78236094448,3
4,9161,7158,2101,51004,932400101,5189015204,87240095449,8
5162,4158,21031005,032440103187015404,96244094449
5,09162,4158,2104,51005,122480105,3187015605,06248095448,3
5,18163,2158,21061005,212520106,8&a

 

As you can see, this way it is very easy to see how the engine performs at a specific rpm and pedal position.

Depending on the project several different driving conditions are needed during the logging.

In case of tuning an OEM ECU and OEM engine, a WOT (Wide Open Throttle) run in 3rd gear gives good information for making a proper tuning.

On dyno:

make sure the engine is working on normal operating temperature. Set correct load value, arrange proper cooling by a fan which simulates real driving wind on the engine, intercooler, but also under the car to cool the exhaust. Set ambient correction to DIN values.

On road:

find a good, safe, quiet piece of road where you can test safely. Note the current ambient pressure, temperature and humidity because we have to take this into account when analyzing the data.

The biggest problem when datalogging many cars is that there are not enough channels available to log.

Beneath we will give a list of channels which are the bare minimum:

It is of utter importance to always log the engine speed i.e. rpm and the pedal position or engine load to see what the driver requests of the engine. Other preferable channels depend on the type of engine, so cast a glance at the general tips below.

For turbo petrol engines we need to see actual boost before and after tuning. If the actual boost is not available, at least measure intake manifold pressure.

For turbo diesel engines we need to see at least injection in milligrams or even better, injector pulse width.

For all petrol engines we need to see actual lambda. If no OBD data is available, an external lambda sensor in exhaust is the last resort.

In case of older cars the external wideband lambda sensor is even better. Namely, old cars often have the narrowband lambda sensors installed when the car is not accurate on the WOT run.

Of course, the ECU knows this and when going WOT, the ECU does not use the lambda sensor to control fuel but instead uses the fuel maps inside the ECU. So when a narrowband sensor is installed and you log this data during WOT, remember not to use this data.

For all petrol engines we need to see ignition or even better, ignition adaption. Ignition adaption allows us to see the ECU correcting ignition according to knock and temperatures.

In short:

  • Datalogging should be inevitable when tuning
  • It should start with the baseline of an original car
  • A list of channels to log and a real-life example are available on this page
  • There are many channels desirable but not all are always available
  • However, there are necessary channels for every type of engine and you can find them in this article

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