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Mitsubishi 6A12 advice required


Craig Tickle

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Hi,

I'm after some info on the Mitsubishi 6A12 MIVEC engine from a 1995 FTO.  The plan is to use a Storm ECU to replace the factory ECU

The wiring diagram (see below)  for the car shows separate  MIVEC controls from each bank going to the factory ECU.  Is there any reason what they can't be commoned to one AUX output ?

My understanding is that this version of MIVEC only requires a rpm switched output  and I don't need to do the full VVT thing.  Is this correct ?

The engine has a thing called a "Variable Induction Control Valve Servo", which internally has 2 hall effect senors and a motor, both motor terminals and the outputs from the hall effect sensors go back to the factory ECU.

My guess is the hall effect sensors tell the ECU when the valve is in the open or closed position so it can turn off the motor and that it's not a continuously  positioned thing.  Can anyone confirm that ?

What would be a good approach to driving this thing ?  I did come up with the god awful  relay network below which only consumables one AUX output but it kind of offends me. Surely there's a more elegant method.

Cheers

Craig

FTO.PNG

Variable Induction Control Servo Relays.jpg

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Hi Craig, I don't have experience with this engine, so can not say about the 'Variable Valve Induction Control Servo'. However if the 2 VTC solenoids are on/off based on RPM then you could operate them off 1 Aux Output provided that the combined current draw is not more than the Aux output can supply. Normal Aux Outputs on the G4/G4+ can supply 5 amps when driving low. You could always use a relay also.

Hopefully someone who knows the engines will be along soon.

Scott

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  • 2 months later...

I have some additional information I managed to extract out of the stock ECU.

Mivec.  

  Both solenoids are activated together at about 5700 rpm, current draw is 1.4 A per solenoid.

  The solenoids are pulled low for about 1.5 seconds, then the ECU swaps to a 50% duty cycle square wave at about 350 Hz  (Mivec scope trace.gif).  

 Is it possible to configure an Auxiliary Output to do that?  It appears that the square wave is just to reduce the current through the solenoids  I didn't notice any PWM happening in any of the runs.

Variable Valve Induction Control Servo.

 First point  - my relay network above won't work

 The servo is a straight DC motor driving some reduction gears and then a worm drive (current draw is about 1.2 A).  The hall sensor magnets are mounted on the worm gear shaft and it takes about 5 turns on the worm gear to make the valve change state.

 The Hall effect sensors give pulses while the valve is changing state but you can't sure that the end state will be different to the start state. (Induction valve.gif).

 I guess the way to drive it could be, Apply power to the motor when the pulses stop remove power so you don't  burn out the motor, is there a way to do that?

Ignition

Just for  completeness here's a scope trace of the crank angle and cam angle sensors at idle (ignition.gif)

Blue is cam, red is crank. There's 4  triggers on the cam (1 is wider) and 3 on the crank.  I believe this is the same as a GTO can any one confirm this?

 

 

 

 

Mivec Scope Trace.gif

Induction valve.gif

Ignition.gif

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No easy solution for the runner control.

For the Mivec you could use a GP PWM output to give the a duty cycle which you could set a narrow RPM range as 100% and then drop back above that RPM to 50%. However in the past we have just driven the solenoid at 100% for the whole time Mivec is active.

Trigger is a match for the GTO pattern.

 

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Thanks Simon,

I guess I could drive the runner in a similar manner to how you suggest I do the Mivec, but set the PWM duty cycle after the rpm window to something really small.  And just ignore the feed back signals.

I'll also investigate adapting a solenoid that is simpler to drive from a different engine.

Craig 

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