There is something that I don't like about my 3.9 hotwire - the way that the ECU keeps the air bypass valve open when I lift off. This manifests it'self in two ways: 1) There is little or no engine braking. In fact sometimes it will actually pull against the brakes when stopping. And 2) If you dip the clutch and coast to a stop then - until you actually get below about 5mph, the revs stay high (1800rpm) and even when you stop they take several seconds to return to tickover.
Previously I have removed the wires from the speed transducer when driving off-road which prevents this annoying trait, however I can't do that when on the road since it also kills the speedometer.
Also previously I thought that the (electronic) speedo was driven by the ECU, but in this I was wrong... While trawling through the wiring diagram yesterday for something else, I noticed that the wire from the speed transducer does not just go to the ECU, it branches and the other branch goes to the speedo. Now since the transducer simply switches 12v on and off I reckoned that if I disconnect the wire from the ECU, the speedo would still work but the ECU would think I was stationary and give me proper engine braking again.
So - to cut a long story long - I cut the correct wire and it works. I now have almost normal engine braking and a working speedo.
p.s. If anyone is thinking of doing this, be aware that there are 3 yellow wires into the ECU so make sure you get the correct one!
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