I've been trying to figure out how an ECU works, technically.

I know in general terms that it uses the MAS sensors in the intake and the o2 sensor in exhaust to monitor how much air is comming in to determine how much fuel to mix. It also watches the o2 levels of the exhaust to cap the mixture's max. Also monitors the valve positions, intake pressure and temperature, etc.

as more air comes in, more fuel is needed. kinda maintaining the air/fuel ratio at different engine speeds, i guess.

But, how does the ECU upgrade work? just expand the pulse width throughout the band? change the max/min offsets? increase the a/f ratio? What exactly is being done? what kinda hardware is needed to flash ur ecu? any good links on this kinda stuff?

thx guys!

 

The ECU does a LOT more than the basic functions you've mentioned. A whole lot more. Yes, those are the basics, but the amount of maps in that little black box border on the limits of comprehension. O2 sensors don't monitor air coming in, they monitor AFR post burn. The Mass Airflow Sensor monitors air going in, the Barometric Pressure Sensor monitors your atmospheric pressure, the Ait Intake Sensor measures the temp of your the air going into your engine, the coolant temp sensor measures the temperature of your coolant, the oil pressure sensor makes sure there's enough pressure to flow your oil, the Cam Position Sensor measures the orientation of your camshaft, Vehicle Speed Sensor monitors and reports the car's speed, tachometer counts RPM's... and this is just the major ones (in slightly more detail).

How upgrades work depends upon what the upgrade is. A reflash alters the ECU's maps. Generally speaking they advance ignition timing and add fuel to improve power.

Piggybacks alter the signals received by a few key sensors (generally O2 sensors) and allow for fuel adjustments to be made to improve performance.

Standalone ECU's allow for COMPLETE mapping, and more importantly, monitoring of the ECU and (generally speaking) all of its functions. Standalone is when you realize how much of the car your ECU controls, from fans to lights to AFR's to ignition timing to just about everything that requires voltage.

My own personal advice: Don't get in over your head when it comes to ECU's. It's a very easy thing to do barring prior experience.

 

Thanks, lots of good stuff. I know the ECU does watch alot more than I mentioned (and alot more that you mentioned as well). It basically takes input from almost every sensor under the hood and formulates the outputs to control fuel spray timings, spark timings, valve timings, etc. In any car this is a lot to wrap your head around. With the MIVEC, im sure its even worse!

But, it really interests me. more than anything else on the car. Im a unix software developer by profession, so you my see why.

Anyway, im getting a better picture of things, especially of how the standard mods work (piggyback for exampel). It seems like it just resists some sensor outputs to decrease them and amplifies others in increase them, making the matrix lookups skewed to provide 'better' results.

This is great, but why not jump straigt to the punch? All the specs I could dig up show that almst all ECU's are RS-232 compatable and that the lookup tables can be rewritten. Im sure the functions can be, as well.

Anyone know of any way to rip the binary off of the ECU ROM to analyze? im interested in the algorythms and th values stored in the tables.

would be cool to simulate all the sensors to see what is optimal by using software.

thx again!

 

If anybody knows its probably ROCK...maybe you could PM him about it.