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Electronic speed limiter on MS?


twodoorgaz
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Could anyone tell me if MS has the capacity to apply a top speed restriction? (full kit on Thor 4.6RV8).

Something similar to the later Defenders but the limit set to match the speed rating of the tyres. On the TDCI Defenders I've driven the car simply holds at at the set top speed (just over 80 MPH) and won't go any faster

Many thanks.

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To my knowledge, not out of the box.

You would need a speed sensor (reluctor ring and sensor) or a gear selector switch and a conditional rev limit. Whilst some versions of MS have speed inputs, I don't think a speed limiter was written into the code. You could write it yourself if you wanted.....

Do other people drive your truck or do you just not look at the speedo much?

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The speed sensor is not difficult, ABS halfshaft and case or electronic speedo. But the speed control is I believe throttle controlled whereas MS controls ignition for rev limiter?

You would need a throttle controlled by stepper motor to limit speed which would require a full fly by wire system or possibly retro fit cruise control if such a thing exists that is electronic?

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MS can do fuel & spark cut rev limiting / basic traction control (anti-rev) depending on setup (EDIS can't do spark cut), but doesn't natively have any handling of road-speed sensors. MS2 / 3 might have, there's a lot more room for bells & whistles in the later CPU's.

As Sid says, for pukka speed limiting as happens on modern cars you need fly-by-wire throttle or you're being a bit hard on the engine. You could possibly rig something up to push back or limit the throttle / airflow but it'd be a bit bodgy.

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  • 3 weeks later...

You could use the alternative map function that MS has, just have a second map that backs off the timing dramatically and runs a reduced fuelling map. If you wanted to get into the code in MS you could potentially link it into the spark inhibit that the rev limiter can use. While it wouldn't be a hard limit on the speed it would be similar to the Land Rover method of vastly reducing the available power. You can also phase the two maps in/out so that it gives a smooth transition either side of the speed limit.

To trigger the second map you'll need a speed sensor circuit that can activate the signal to change maps when the speed exceeds your limit. There's probably something out there that can be modified to suit.

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If you dug into the code it shouldn't be hard to hack up a speed limit system using the 2nd trigger/tach input code, all you need is a configurable cutoff frequency/count and a signal conditioning circuit on the input - an ABS sensor is amazingly similar to a crank sensor funnily enough ;) so re-using the MS VR/Hall sensor input circuit should have the hard work done for you - then link the tweaked input code to activate the existing rev limit code.

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