MAP Sensor Adjuster on Renix ECU.........

[Wild Comanche]

Just wondered if anyone has tried using a "Split Second ARC 1"  MAP adjuster on their Renix 4.0l Jeep?  Thanks.

[HOrnbrod]

They have been around for years. It allows you to adjust the MAP 5VDC reference voltage to control the A/F ratio. You can make your own:

 

http://gojeep.willyshotrod.com/HowtoMAPsensor.htm

[Marine1Texas]

I seen this one http://www.strokedjeep.com/regulator.html however never tried it. I think the 60mm throttle body with more lbs injectors is well worth it and cheaper. However that's my 2 cents

[Wild Comanche]

Thanks for the info..  I appreciate it.  This Jeep has a modified engine but I'm still using the factory stock injectors.  It runs rich when cold, 10.5 to 11 A/F ratio, but when it is warmed up it varies between 13.8  to 14.3 A/F ratio.  Those readings are from an AEM wideband A/F gauge.   Can't really figure out why with all the modifications it isn't running leaner.  I think those stock EV 1 injectors are only rated about 19.5 lbs./hr. @ 43 p.s.i.    I have some EV 6 22 lbs./hr. @ 43 p.s.i.  injectors, but haven't installed them yet.  I installed an inexpensive b50k potentiometer on the reference wire on the MAP sensor and it leans the A/F ratio.  Any leaner than the low 16's and the engine begins to stumble.  Anywhere around the high 14's to the mid 15's it runs smooth.   I realize the simple potentiometer I have installed now is not a permanent fixture,  just wanted to experiment and see what happens. 

[Marine1Texas]

did you move your air temp gauge from manifold to your cold air intake? That on my 87 seem to make mine run smooth when I did that. I run HEI and have it advanced good, with a nice advance curve. not had it ping once with my advance. Since I added the over size throttle and the injectors that are 21 lbs it has so much more pep and grunt.

[Wild Comanche]

Thanks for that tip. I have an aftermarket air intake/filter setup. Relocating the IAT sensor could be done. In the cold of winter it would seem that the sensor would be picking up cold temps most of the time. I wonder how that would work out?

[HOrnbrod]

This is true. So in addition to the stock IAT sensor on the intake manifold I have a separate IAT sensor drilled and tapped into my air filter inlet tube. I use this location in the summer to richen the mixture up a little, then during the cold months connect up the stock IAT sensor. You have to extend the IAT harness a little so it reaches both locations.