Technical > Wiring & Sensors

VEMS on Supra MKIII 7MGTE?

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PeepPaadam:
Hi guys,

I'm going to install VEMS on 7MGTE engined Supra that has automatic gearbox. Car has cruise control and air conditioner too.

I have severel pinouts regarding this ECU.

I'll be using mostly factory loom but I'm going to install crank sensor as I understand there's CAS wheel on camshaft? I'd rather not use it.

If anyone has experience/suggestions/hints on this one, please chime in.

TIA, Raceboy

BenFenner:
Why not use the CAS wheel on the camshaft? The only problem if I remember is that it causes a poor idle, and that holds true with the stock ECU as well. Meaning, you should be able to have idle just as good as stock with it using VEMS.

PeepPaadam:
So I found  a sensor datasheet for 7M-GTE (available here: http://www.autoshop101.com/forms/h23.pdf ) and it has G1, G2 (both reference sensors) and Ne (rpm sensor) on camshaft.

Question is do I have to use all three of them or can I get away with just one reference (G1 or G2) and rpm sensor (Ne)?

I don't see any reason why straight-6 couldn't idle smoothly, I'll change out the idle valve if I need to....

BenFenner:
I don't see why you shouldn't be able to just use the signals you're interested in. If you just want to use the crank (rpm) signal, that should work just fine.

The reason for the poor idle (which your car has from the factory) is because you have a belt, or chain driving the camshaft. This introduces slop between the crank and the CAS disc. This means the ECU doesn't get the correct timing at idle, and can't do a terrific job of controlling rpms at that engine speed. I have the same thing on my Nissan SR20DE. It is not a big deal, as it is almost indistinguishable if everything else is working correctly. You could try watching your car idle, and pay close attention to it, then get in something like a BMW (same straight six engine configuration but with a crank wheel) and watch how rock solid the idle is.

PeepPaadam:
It's my friends car, not mine :)

Because of the cam slop I'd like to fabricate crank trigger but if I could use stock trigger arrangement easily, I'd go that route.

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