Mercury ECM/ECU tune or swap question

[smoken86]

Finding anyone to touch anything other than a old 300xs is going to be difficult. Mercury won their lawsuit against some companies that were modifying PCM's and it cost them a pretty penny. Last time I asked about my 250xs they all acted like I was asking for cocaine.

It pisses me off that some models can be modded and almost everything else cannot. Also that Yamaha and every vehicle on the road can be without penalty (unless it is a diesel). Because according to Mercury we don't own it.

But it is what it is until someone is willing to fight Mercury with way more money than I.

[lpugh]

I have been wondering the same. If you swap a 80mm throttle body on a 200 and put on a 300 Pro XS pcm what would happen? Let's put the you'll void your warranty or Ecu tampering is illegal discussion aside.

Will it run?

Other question is if you can swap on the 80mm throttle body on a 200.

Don do these motors run open or closed loop? If they're closed loop then you should be able to put the larger TB on and the motor will adjust fuel trims for the extra air.

Motors that do use closed loop strategy (Oxy sensor in system) at very heavy loads or near full throttle go into open loop and ignore the O2 sensor, using only the mapping tables for fuel and timing. Under those conditions about a 12.5 to 1 AFR instead of stoichiometric 14.7 to 1

[lpugh]

Finding anyone to touch anything other than a old 300xs is going to be difficult. Mercury won their lawsuit against some companies that were modifying PCM's and it cost them a pretty penny. Last time I asked about my 250xs they all acted like I was asking for cocaine.

It pisses me off that some models can be modded and almost everything else cannot. Also that Yamaha and every vehicle on the road can be without penalty (unless it is a diesel). Because according to Mercury we don't own it.

But it is what it is until someone is willing to fight Mercury with way more money than I.

The bigger concern is EPA, this not legal on any motor by any manufacture, EPA has put many of these violators in to bankruptcy recently!

[low slung cruiser]

Motors that do use closed loop strategy (Oxy sensor in system) at very heavy loads or near full throttle go into open loop and ignore the O2 sensor, using only the mapping tables for fuel and timing. Under those conditions about a 12.5 to 1 AFR instead of stoichiometric 14.7 to 1

So is the only difference the throttle body? Or would a bigger throttle body and reprogramming of the computer be required to increase the HP?

[mactlman]

So is the only difference the throttle body? Or would a bigger throttle body and reprogramming of the computer be required to increase the HP?

The 200-225 V8 have drastically smaller throttle bodies, which are holding back the engine from revving above 5800 RPM usually--the mapping will be different but the ecms also can adjust some within a preset range also

[EuropeanAM]

ETC (Electronic Throttle Control) is not the only difference in the engines.