megasquirt vr sensor on cps issues

[Pyro15D]

Hey, I am installing ms2extra on my 7mgte and everything works apart from the cps. I have yet to install it, but I bench tested it using a drill and it loses sync below 500 rpms. Now you may think that it isn't that big of a deal except its too low to even start the engine. Now, the clearance between the rotor and the vr sensor is pretty much nonexistent. It's just far enough to not be touching the rotor. Anyway, what can I do to help with low rpm sensitivity?

 

[3p141592654]

You need a better VR sense circuit. Buy a 7MGE ECU for $25 and pull out the VR circuit components, then make a printed circuit board at Dorkbots to mount them up.

 

[Pyro15D]

I didn't even think of that. I was about to design an optical trigger disc and mount that on there and use one of my infrared sensors. I can try that though. From what I read, vr sensors are simple but very susceptible to noise and such.

 

[3p141592654]

Like all analog circuits, they need to be designed by experts who understand noise and signal processing issues. The ECU uses a Denso chip after the filter chain that converts it to 5V TTL.

Denso hired the best back in the day, MS was done by amateurs for the most part, and their VR sense circuit is not well designed, as you now know.

 

[Pyro15D]

Yeah, I just figured that technology now would be better than back in the 80s when the circuit was designed. While we are on the subject of the ecu, what is the part number of the vr conditioner chip? Or, let me ask you this. If it was you who was installing this, would you use vr or would you go for an optical trigger?

 

[3p141592654]

You are asking the wrong person, because I would use the stock ECU running my daughterboard allowing full programmability. But anyway, the 7MGE ECu uses the Denso SE022 chip to condition the VR signals. The circuit looks like this

 

[Pyro15D]

I had one question. Do I gave to use the ge ecu or can I use a GTE ecu?

 

[3p141592654]

Doesn't matter. Whatever you have access too. If you're just tearing it apart, the GEs are usually cheaper.

 

[Enraged]

This might be an option for you: http://saturnwiki.net/wiki/index.php?title=Nippon_Denso_CAS