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Old 09-02-2020, 01:49 PM   #18
DailyDriverMods's Avatar
Join Date: Aug 2020
Location: Netherlands

Originally Posted by bobxyz View Post
To drop the LH2.4 MAF voltage, you can just use a 2 resistor divider. I'd try a total resistance around 50K to keep the load on the MAF low.

Your bigger problem is that LH2.4 uses a hot-wire MAF that needs an occasional burn-off cycle. I don't know how you'll do this with megasquirt. It would be easier to find a more modern thin-film MAF that doesn't need a burn-off cycle, preferably one with a good MS calibration chart already available. (I think ipdown still has partial datasheets for the 012 and 016 AMMs.) Or just use MAP like everyone else suggests.
The MAF burnoff cycle would be done as following:

The MS2 got programmable outputs. One output would go high when:
runtime -> 20 minutes

This signal will be fed into a ATTINY microcontroller. Once it detects that the signal is high, it will trigger the following routine:
- Once the signal goes low again (that's when the engine is turned off), the system relay will be kept turned on and the MAF buroff signal will be sent for a period of time. (somewhere from 5 to 20 seconds i saw in the documentation)
- Once this time threshold is met, the burnoff signal will be low again and the system relais will be turned off. Easy as that. (LH isn't really that complex)

But since i'm probably going to swap the MAF right away, i won't be using this.
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