Technical Question
08-01-2009, 11:51 AM
#1
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Year: 1994
Model: Cherokee
Engine: l6 HO
Technical Question
I want to up my idle when my AC is on by around 250-500rpm's. I know that some jeeps (police, government ones) had this option so does anyone know what mods to the CPU have to be made?...Tj
Last edited by TrekkerJmm; 08-01-2009 at 12:31 PM.
08-01-2009, 03:20 PM
#3
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Year: 1988
Model: Cherokee
Engine: AMC242
You're probably thinking of the "Extended Idle" switch - which set the idle up around 1000rpm by pressing a switch on the dashboard (mainly to provide additional alternator output, to drive lights/radio/&c on police models.)
I believe it's wired into pretty much any OBD-II PCM - the problem is that your 1994 is OBD-I. You'll find the mod covered in fair detail on NAXJA.
As far as a full DIY version, you may have trouble. You'll need to either have access to the stepper motor that controls the idle (the IAC - which already opens up slightly to keep the idle up with aircon load on,) possibly find a way to fool the PCM into thinking the aircon is on when it isn't (I haven't looked into this,) or use a friction-lock control cable to make a bypass hand throttle (these can be had at most industrial equipment supply houses - I used to put them on forklifts often to give better hydraulic performance at idle.)
I believe it's wired into pretty much any OBD-II PCM - the problem is that your 1994 is OBD-I. You'll find the mod covered in fair detail on NAXJA.
As far as a full DIY version, you may have trouble. You'll need to either have access to the stepper motor that controls the idle (the IAC - which already opens up slightly to keep the idle up with aircon load on,) possibly find a way to fool the PCM into thinking the aircon is on when it isn't (I haven't looked into this,) or use a friction-lock control cable to make a bypass hand throttle (these can be had at most industrial equipment supply houses - I used to put them on forklifts often to give better hydraulic performance at idle.)
08-01-2009, 03:23 PM
#4
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Year: 1994
Model: Cherokee
Engine: l6 HO
Thanks for the reply, I'll have to do some research on this. I will write back on my findings, if any at all...Tj
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