Friday, November 22, 2013

The Mx - RB30 Throttle Position Sensor (TPS) Mod

I shall tell this story via a photo gallery, but first an explanation as to why.  I have installed a Megasquirt into my 89' 1.6L Mx5 and by default it ignores the TPS because it is crap.  You see the stock TPS is a switched type which tells you 3 states: No throttle, some throttle, Wide Open throttle.  This doesn't help the ecu much and definitely doesn't help if data logged.  So I needed a new one.  A few forum posts said that an RB30 TPS had an extra connector that would work for what I wanted so I ordered one off ebay.  When it arrived it is quite a bit smaller than the stock one, but the mounting holes do line up with some other holes on the throttle body.  The problem though is the throttle shaft is too long, so I need a spacer.  A few hours in Sketchup and a call to a mate later and I had an adapter printed.

Now to problem two.  The variable signal comes out of a separate connector on the TPS and it is different to the plug on the stock loom.  I could just buy two new connectors, chop up the loom and connect it that way, but that would mean definitely no going back to the stock ecu unless I modified the stock TPS as well.  But then I noticed something.  The hard connector on the RB30 TPS was the same as the stock TPS. I just had to internally re-wire it so the variable signal comes out of that connector.  And that is where the photo gallery begins!

1 comment:

  1. Thanks for this, will be attempting to replicate your method on the weekend!