1996 Mercury 200 hitting rev limit

[Mercury1010]

I have a 1996 Mercury 200 EFI that is hitting rev limiter at 4000 RPM. Found by checking systems with DDT that when the tack is reading 3000 RPM DDT shows over 5000 RPM and the tachometer is correct RPM. Mercury has no suggestions

 

[Dukedog]

trash tha "idle" speed box.. it has white/black, white/red wires going to tha switch boxes.. you may have to make a short white/black jumper that goes between tha bias post of both switch boxes.. reset "max timing" at 23*... if that doesn't help ya probably gonna have a suspect ecu............ jmo.

 

[Faztbullet]

Do the above..and if ECU is suspect ,send to Brucato to have tested and buy his ACU if it comes back defective.

 

[Mercury1010]

I have a 1996 Mercury 200 EFI that is hitting rev limiter at 4000 RPM. Found by checking systems with DDT that when the tack is reading 3000 RPM DDT shows over 5000 RPM and the tachometer is correct RPM. Mercury has no suggestions

Do the above..and if ECU is suspect ,send to Brucato to have tested and buy his ACU if it comes back defective.

I have disconnected the idol stabiliser module has disconnected the knock sensor module have tried 2 other easy ECU. It's still does the same thing 3500 RPM DDT shows over 5000 RPM

 

[Mercury1010]

I have disconnected the idol stabiliser module has disconnected the knock sensor module have tried 2 other easy ECU. It's still does the same thing 300 RPM DDT shows over 5000

After many hours going through systems found that an aftermarket switch Box was causing the problem