For those of us who've converted an EL to manual know only too well how s**t the engine is for engine braking down hills.

There's 4 litres of 9:1CR in there so there should be a s**t of engine braking available however the ECU keeps the ISC wide open so engine braking doesn't occur. It also sucks when upshifting because the revs dont fall quick enough to make a smooth change.

So for the past couple of years I've been driving with the ISC disconnected and with the throttle butterfly cracked open enough to idle it at 700-ish RPM once warmed up.

Problem is when its cold or when the AC is on - there's nothing to supply additional air to up the idle so for the first minute or two when cold, it will stall if you get off the accelerator and in the summer when you put the air con on, it almost stalls. Just enough to tease you but it stays alive. My solution during the summer was to up the idle to about 900rpm which drops it to 600rpm with the AC on and doesn't get near stalling.

Where's this leading? I want to drive the ISC from the AC signal and when its cold with an external source.

I dont care for power steering idle-ups or alternator idle-ups or anything else, they only affect about 100rpm or so, nothing to write home about.

Firstly, is the IAC driven by a switched 12v source, a variable DC source or a PWM source?

If its just on/off activated, my plan is to simply connect the AC wire to the ISC so when it's on, it ups the idle. The second part of it is to make a small circuit with a high gain op-amp using a gain of about 500 or more to open the IAC based on engine temp, until its warmed up about half way then close it. I'd use a diode to isolate each circuit from the other.

If its voltage or PWM controlled, a better idea would be to allow the throttle to close even more so the idle would be perhaps 500rpm with the ISC closed and have a medium gain op-amp control its opening via engine temp, RPM and AC inputs. It would almost be a good idle speed controller for a variety of cars.

Thoughts/ideas/critisisms?

whne you had your ISC connected did the idles go up to about 1100+ rpm ?
cause when i converted mine it was all fine and that was using the auto ECU too , mind you i did do the resisters aswell for tricking the ECU

I did the resistor mod and the idle is perfect with the AC on, driving lights and all electrics on, when cold everything is right.

But the engine response is s**t, holding the revs when you let go of the accelerator. Once you disconnect the ISC, the engine response is pretty good but all the other problems happen.

I dont have a drony exhaust so running rich on decel doesn't bother me, popping and f@rt wont occur due to standard exhaust.

ISC has constant positive with ignition on, and the ECU used PWM to control the negative.

I Made an adjustable controller for the EB when I got my Ex cab years ago, I used the Jaycar 20amp dc motor controller. It worked a treat - I had 2 knobs on the right of the steering column. One was the adjustment knob, which pulsed the ISC fully closed or fully open, the other knob was a 3 way rotary switch to have the ISC either Off, Variable or ECU controlled

I shuold also add, I had this connected to the remote start as well so I could rev remotely

hahahaha

Alrighty, I'll be working on a PWM solution for idle control... Its just gonna be open loop but I'll get something working...