Have Datascan ECU diagnostics softwware running in my zed, and noticed today that one of the output displays shows when the car is in Neutral or ingear on a manual transmission.

 

Could'nt think of a reason why the ECU would require this information, just curious really....anyone know why ?

 

(its probably blindingly obvious, but I just cant think of it :slap: )

ECU needs to know this so it doesn't kick turbos/boost in unless the engine is under labour.

fuelling?

cruise control, starting?

The ECU uses the speed signal and rpm to calculate what gear you're in so the ECU knows when to switch to the high gear fuelmaps.

For this the ECU also needs to "know" exactly when you're actually in or out of gear and it does that by sensing the neutral gear switch.

 

-Eric

ah, brilliant. Makes sense now. Thanks :D

Eric, does this switch need to be used in a auto to manual conversion??or has the ecu for auto a different way of sensing

Richard

for automatics it works a little bit different, since the AT ECU will communicate to the engine ECU when it's changing gears (among some other parameters)

 

if you don't have the neutral switch or it is malfunctioning the ECU will never switch to the high gear fuelmaps, but it won't do any damage.

if you do have it, but you're using an AT ecu/rom it won't use the signal.(which is actually a good thing, because the gear formula is quite different for autos and could cause problems in a manual car)

 

In stock configuration it will switch to the high gear maps as soon as you hit 4th gear or 3rd gear in an automatic.

 

I have noticed myself that if it switches too early it could cause detonation.

This is the case if you are using a NA diff on a TT, since the formula the ECU uses to calculate what gear it's in will be off.

In this case it's best to either diable the switch by cutting the wire or disable it in the ROM of the ECU.