JTEC MAP Scale

[Rex_Rat]

I have gone through some posts in the history that deal with the MAP sensor but have not seen how a resolution was come to. I have a 1996 RWD 2.5L in a Dakota. I made a pressure voltage table for the old OEM 1Bar sensor and have also mapped out the new 2Bar sensor. As I am only using the sensor to read 6lbs of boost the voltage swing is from 0.788V (14.4Kpa) to 3.34V (6PSI)

Question 1 What is the "Sacle" function in the MAP sensor section?

Question 2 How do I modify the values to suit the new sensor?

Question 3 Has any one running 6Lbs of boost on a 2.5 run out of injector with the OEM injectors?

Question 4 Is there a plug and play standalone ECM option for this vehicle?

Thank you for your time.

I have built a micro controller running a DAC. It outputs 9 voltages that are switched with respect to the voltage that is coming from the new sensor. No changes to the MAP sensor section needed and all nine cells are available for tuning. Is this necessary?

RR

[Endwrench]

I've been doing a little research on boosting my Dodge magnum with this system and near as I can tell you can't scale the map. Most people running less than 11 lbs of boost are using a stock Honda map from a normally aspirated. It's like 1 3/4 bar. This will give you a little better resolution.

I don't know what DAC is but it needs to output a linear voltage. It would need to convert a 0 to 3.5 volt signal (your 6lbs on a 2bar sensor) to 0 to 5 volts this way you could use all 9 cells for tuning.

[Rex_Rat]

It certainly is a challenge!

A DAC is a digital to analog converter. The micro controller reads the 2bar sensor then outputs one of nine voltages that correlate to the voltage output of the original sensor.


If you download the tune from the ECM go to the "Airflow" page you will see several fields "MAP WOT Depression" "Map Scale Mult" "Map Scale Add" MAP WOT Count" I would prefer to manipulate these fields rather than use the DAC. I will use a spare ECM to rig on a bench to test how changes on the MAP fields change the output of the ECM: PIDs and injector pulse width. However this all takes time and Ill be up and running on the DAC before I am able to lift the lid on the scaling feture of the ECM. I was hoping someone here would help to prevent me from having to spend all that time I'm not tuning these computers for others. No interest in selling tunes.

[jbliss15]

I'm interested to learn what happens. I'm running the Honda 1 bar and scaling manually in base tune

[EvilR/T]

Thomas Beyer on youtube has a video or 2 working on the MAP table for his Super Charged Cherokee.

[MonkeyMike]

What?s the update on this? I?m about to start experimenting with the values if nobody else has any data to provide.

I figured hook up the Honda D16/17 map sensor and leave the engine off, attempt to get the sensor to calibrate to atmosphere via OBD2. After that, hook up an air supply line to the map sensor and set to 10psi, then see if the jtec will display it on the readout boost at all. The map values can be changed in hptuners on the tables, we just need the controller to see the values while reading the sensor.