Jtec boost

[mtm-mora]

Hello fellows I'm researching how to setup or scale a 2 bar map sensor I'm planning to boost my wj 4.7 but first I want to know everything about it I know the theory and I have all the knowledge to build de turbo system but I don't know how to set the ECU to read boost if someone can help out with this will be much appreciated

[jefo]

The scaling for the map sensor is the easy part; If its an srt4 map, the data is readily available. Then you'll need bigger injectors and input the data for them. Then have to adjust the timing maps and fueling maps for boost using a wideband o2 sensor.

First thing other will ask is for you to read and post your tune file here, and maybe others can chime in, as I have not dealt with the 4.7 specifically.

[veeefour]

Boosting J-Tecs require...different approach...

[hyperbolecubed]

Just installed a supercharger to my 97 Jeep 4.0 and when i start it the engine starts screaming to and past 3k rpms. Im trying to fiddle around with scale to no noticeable change.

[GoldenGorilla]

Assuming you didn't have the intake manifold off for any reason and don't have an intake vacuum leak. This will cause a runaway idle.

The startup process checks "barometric pressure" voltage from the map sensor. Your new map sensor is reading a voltage that probably makes the pcm think it's parked on everest and it's opening the IAC too far. You need to tell it to delay the barometric reading at startup by entering a very high number of milliseconds it will accept.

[hyperbolecubed]

You were correct. I had an obnoxious amount of vacuum leaks. Just fixed them and fired up the jeep with supercharger and it idles 800 rpm and runs way better. Running insanely rich though.

You said to delay the start up for barrometric pressure updates to a higher number. However, the highest number can be 2805 microseconds/2.805 milliseconds [ECM] 47229 - Barometric Pressure Minimum Time After Start for Update: When running, this time must past before allowing BP updates.

Thanks for your help!