MSefi.com read only forum (Jan.15,2018)

im hearing alot of bad things about stepper motors and about pwm idle valves being rather difficult to make act right. so ive set up a solenoid type fidle valve to help with cold starts and that works fine. however, i just added a/c and id like to raise the idle speeds by a couple hundred rpms to compensate and the fidle valve isnt quite suitable since its a boosted application. what im thinking is to use a mechanical type idle speed controller like some of the ones ive seen on 80's model cars that manually moved the throttle plate instead of bypassing air like a typical iac or stepper. anyone have any good thoughts on this or know of a good vehicle to get one of these from? any other ideas to build something simple? ms doesnt really even have to control it, id be happy if it just functioned with the cycle of the a/c. thanks in advance.

pure insanity wrote:im hearing alot of bad things about stepper motors and about pwm idle valves being rather difficult to make act right. so ive set up a solenoid type fidle valve to help with cold starts and that works fine. however, i just added a/c and id like to raise the idle speeds by a couple hundred rpms to compensate and the fidle valve isnt quite suitable since its a boosted application. what im thinking is to use a mechanical type idle speed controller like some of the ones ive seen on 80's model cars that manually moved the throttle plate instead of bypassing air like a typical iac or stepper. anyone have any good thoughts on this or know of a good vehicle to get one of these from? any other ideas to build something simple? ms doesnt really even have to control it, id be happy if it just functioned with the cycle of the a/c. thanks in advance.

Some '80s EFI systems used a Bosch extra air valve which is totally stand alone. It works on a mixture of engine temperature (contact through its body) and a electric heating element which is simply powered from the ignition. It fits in a bypass hose round the throttle. It's pretty foolproof and reliable. Only snag is it has to be mounted on a flat surface on the inlet manifold etc so it gets the heat transfer from that.

Many VWs ( Golf, Polo 90´s stuff ) has a unit sitting close to the throttle shaft . It is a comboned TPS and idle speed actuator.
The idle speed actuator is a DC motor with gearbox and a plunger that pushes on a lever on the throttle shaft.
Works very well and seems to last forever. Well protected and can be run be a full H bridge with mosfets.

Heribert

alright, thats perfect. ive been thinking about this all day and that sounds like what i need.

anyone else know of something else of the sort? just like to have as many options as possible.

I picked up a small solenoid from a jy car that operates an "air valve" (for lack of a better description). It's one piece (valve/solenoid) and I wired the solenoid to the wire that energizes the ac compressor clutch. When the clutch engages the valve opens and lets a small amount of air enter the intake manifold...essentially a "vacuum leak". The solenoid/valve combo I picked up dumped too much air so I added a restriction in the line to the manifold to get the rpm increase I wanted.

You can find valves that are normally open and others that are normally closed, normally closed is the one needed.

This is a simple, reliable way to bump the rpm...

The stock ISC off your car would work also.