1100 Evo mods - an addicts tale

Luddite · 12-07-2017, 11:19 AM

That Booster Plug mod is interesting but, as Chris says, for the money, a Rexxer remap is better value as it also disables the lambdas and exhaust valve.

There's no real information on the Booster Plug site to suggest how it works but, looking at the installation instructions, I have a theory.

The closed loop system (i.e. when the lambdas control the fuelling) only operates once the engine is up to temperature. This is because you'd never get a cold engine to start and run on the weak lambda mixture (14.7 to 1 air/fuel ratio). I think the ECU uses the intake air temperature (IAT) sensor to decide when to switch to closed loop, rather than the oil temperature (incidentally, the Rexxer remap allows you to read the IAT on the dash).

The Booster Plug is installed between the standard IAT sensor and the ECU. It also comes with a second external air temperature probe (the NTC sensor), which must be mounted in cool air away from engine heat.

My guess is that the unit uses this NTC sensor to fool the ECU into thinking that the engine is always below the temperature at which it switches to closed loop and so the lambdas are ignored.

Anyone else got any theories?

12-07-2017, 11:19 AM	#11
Luddite Registered User Join Date: Aug 2011 Location: Southampton Bike: M1100evo Posts: 2,465	That Booster Plug mod is interesting but, as Chris says, for the money, a Rexxer remap is better value as it also disables the lambdas and exhaust valve. There's no real information on the Booster Plug site to suggest how it works but, looking at the installation instructions, I have a theory. The closed loop system (i.e. when the lambdas control the fuelling) only operates once the engine is up to temperature. This is because you'd never get a cold engine to start and run on the weak lambda mixture (14.7 to 1 air/fuel ratio). I think the ECU uses the intake air temperature (IAT) sensor to decide when to switch to closed loop, rather than the oil temperature (incidentally, the Rexxer remap allows you to read the IAT on the dash). The Booster Plug is installed between the standard IAT sensor and the ECU. It also comes with a second external air temperature probe (the NTC sensor), which must be mounted in cool air away from engine heat. My guess is that the unit uses this NTC sensor to fool the ECU into thinking that the engine is always below the temperature at which it switches to closed loop and so the lambdas are ignored. Anyone else got any theories?