Bounty__Hunter
Super Moderator
Anybody tried this mod of making the MAP sensor adjustible? How'd it work?
Thanks.
Chris
Thanks.
Chris
Adjustible MAP sensor
- Thread starter Bounty__Hunter
- Start date
MudderChuck
New member
Thought about it, but then reasoned it would probably take a trip, to the dyno, to index it someway (puts some marks on somehow to know how rich or lean you were) and always wondered about how it would affect the interplay, with the other sensors (the map and throttle position sensor are wired together in the Renix/TCU) and how running too rich, might heat up the Cat... RF, voltage changes, heat and age, would also probably affect the adjuster circuits (potentiometer and other electronics). I have enough trouble keeping what I have running well, without adding variables.
An alternative could be (just a thought), if you have A/C to unplug the compressor/turn on the A/C controls. Ups the idle and broadens the injector pulse band. As well as turning on the aux fan. Or possibly adding a N/O,N/C multi contact, switch, normal and slightly rich. The imputs (at least on my Renix) could be seperated, with a simple diode and a multi pole switch. Power to the A/C request (at the ECU) after a diode (in the existing circuit) and interrupting the power to the A/C relay coil. Would just broaden injector pulse band width, without uping the idle or turning on the fan and the compressor. You´d just fool the computer into thinking the A/C was on, and richen the mix a bit.
An alternative could be (just a thought), if you have A/C to unplug the compressor/turn on the A/C controls. Ups the idle and broadens the injector pulse band. As well as turning on the aux fan. Or possibly adding a N/O,N/C multi contact, switch, normal and slightly rich. The imputs (at least on my Renix) could be seperated, with a simple diode and a multi pole switch. Power to the A/C request (at the ECU) after a diode (in the existing circuit) and interrupting the power to the A/C relay coil. Would just broaden injector pulse band width, without uping the idle or turning on the fan and the compressor. You´d just fool the computer into thinking the A/C was on, and richen the mix a bit.
Bounty__Hunter
Super Moderator
Does the AC richen the air/fuel ratio, or just up the idle and engage the aux. fan if equipped? I can't see it changing the air/fuel ratio other than is normally adjusted when the idle increases.
MudderChuck
New member
Most of my reading has been with the Renix (might or might not be the same or close, with the OBD). one circuit to the ECU was for high idle (A/C select circuit), another to widen the injector pulse band width (A/C request circuit)(and turn on the compressor relay and aux fan), which sounds like a little richer to me. Just a guess, but the wider pulse band width, probably gives it just a touch more umph at lower RPM´s and might also help with motor cooling a bit, auto 101 taught me, that a rich motor ran cooler, than a lean motor.
The wider pulse band width, could maybe foul the plugs during prolonged idle or heat up the CAT.
I have unplugged the compressor and turned on the A/C, to get the higher idle and aux fan, when doing a lot of low speed wheeling. It´s a quick way to put the aux. fan on, to prevent overheating (if you don´t have a switch wired in, to turn the aux. fan on, before it gets hot) seemed to add a little extra torque to boot. May have just been the higher idle. On many police models, there is a switch to turn on the high idle. Could probably do the same thing, with the A/C request circuit (turns on the A/C relay/aux fan and widens pulse width) at the ECU and widen the pulse band width without the higher idle. Pulling the A/C relay would give you the higher idle and wider pulse, without the compressor or aux fan, with the A/C on. At least on the Renix.
I´m doing gaskets and seals this week, but plan on adding some switches and options, soon.
A/C controls on, compressor unplugged = interior fan, aux fan, high idle and wider injector pulse.
A/C controls on, compressor relay pulled = interior fan, high idle and wider injector pulse.
A little creative wiring, could give you more choices. Might turn out to be an acceptable poor mans, adjustable MAP.
The wider pulse band width, could maybe foul the plugs during prolonged idle or heat up the CAT.
I have unplugged the compressor and turned on the A/C, to get the higher idle and aux fan, when doing a lot of low speed wheeling. It´s a quick way to put the aux. fan on, to prevent overheating (if you don´t have a switch wired in, to turn the aux. fan on, before it gets hot) seemed to add a little extra torque to boot. May have just been the higher idle. On many police models, there is a switch to turn on the high idle. Could probably do the same thing, with the A/C request circuit (turns on the A/C relay/aux fan and widens pulse width) at the ECU and widen the pulse band width without the higher idle. Pulling the A/C relay would give you the higher idle and wider pulse, without the compressor or aux fan, with the A/C on. At least on the Renix.
I´m doing gaskets and seals this week, but plan on adding some switches and options, soon.
A/C controls on, compressor unplugged = interior fan, aux fan, high idle and wider injector pulse.
A/C controls on, compressor relay pulled = interior fan, high idle and wider injector pulse.
A little creative wiring, could give you more choices. Might turn out to be an acceptable poor mans, adjustable MAP.
