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Variable rev limit device based on engine temp?

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Old Feb 18, 2003 | 08:18 AM
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AndyS44
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Anybody know where or how I could build a device to bleep rev limiter at 3k until engine warmed up?? then revert back to set rev limit??

Andy
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Old Feb 18, 2003 | 09:01 AM
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I would also like to know how to do this, but lack the imagination/knowledge to do so .

Chris
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Old Feb 18, 2003 | 09:55 AM
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You can do that. I beleive the engine ECU knows the coolant temperature (but not the oil temperature) and the car's RPM, so you can read them from the diagnostic connector.

You can get both of those readings directly from the electronics too, but don't ask me to translate the volts into real numbers... (won't be too hard if you have the equipment.)

The revs signal will probably be a pulse at a frequency proportional to the rpm of the engine (easiest place to get at it is from behind the dials) and the coolant temp will be a voltage level that is proportional to temperature.

Measure them with your device and output the results...
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Old Feb 18, 2003 | 09:55 AM
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not sure how you'd do it but on my old lancer 2000 turbo there was a little solenoid that stopped the throttle opening fully till the engine had reached a certain temp

only thing id worry about is making sure that in picking up a temp feed you didnt disturb the management system's signal
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Old Feb 18, 2003 | 08:30 PM
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Would a guide not be better than a limiter ? like on the m3 it has leds that illuminate round the rev range that go out when the oil gets up to temp. What happens if u needed to accelerate fast in an emergency ?
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Old Feb 18, 2003 | 10:05 PM
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Why not buy one of the oil temp gauges that flashes when the oil reaches a certain temp? Set it to flash when oil reaches 80 deg C?
I think the SPA digital gauge does this.
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Old Feb 19, 2003 | 08:19 AM
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Yes - only rev guide not physical limiter!

Thanks for all the input chaps.
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