How the 4A-GE ECU works

[SuperHessu]

NoHachi Wrote:Do you know of any people that have succefully installed the Saab Ion sensing iginition into other cars? I know that a lot of people tried but failed..very interesting technology that would allow a HUGE improvement in tuning capability.

Haven't heard of anyone even trying yet, but I have all the original wiring diagrams etc. and I've discussed them with experienced car-electric mechanics and we've all agreed on how to run it succesfully with a MegaSquirt for example.. The wiring is rather simple actually, it needs a solid 12volts, 12volts while ignition on and a ground. Then you control the ignition by connecting the correct pins to earth making the plugs ignite, and then there's two pins giving out the knowledge of the burning, they're grouped so that cylinders 1 and 2 come though one pin and 3 and 4 through one. That's so that the original Saab system would know in what position the engine is. At first when you start the car it uses the crankshaft position signal to get clear of which cylinders are up, and then ignites on 1 and 4 or 2 an 3, then it just checks which pin gives out the fire signal. Naturally if there's a spark on 1 and 4 and the pin of cylinders 1 and 2 tells of a burn, it knows where to ignite next and keeps igniting only one cylinder at a time.. Saab systems don't have a knock sensor at all, but the system keeps monitoring if the cylinders ignite before there's even a spark and that way knows if the engine is knocking.. I'm not gonna try to use that feature but only to get a look at the firing seguence and burning quality to be able to adjust the engine even better..

SORRY FOR THE OT!