Any adverse effect of cutting power to ECU when car is running?

[Kristian_Wraae]

I'm installing an alarm and it has the feature to cut the power to the ignition.

My car is with automatic transmission.

I was thinking of wiring it in so that it will cut the power to the ECU. That should stop the car...

Can anything bad happen to the engine or transmission if the power to the ECU is cut while driving?

 

[PureDrifter]

motor will die, causing the person driving to lose BOTH PS AND power brakes (after a push or so).

other than that, i cant foresee any problems, you won't have the fuel cut/ign cut problems some people have with rev limiters, it would be just like shutting the engine off normally.

thought i've gotta ask how your new alarm is going to randomly decide to turn itself off, i'd rather think an immobilizer system, which prevents the car from being stolen, would be a better buy....

 

[Kristian_Wraae]

The alarm will only turn off the car if I send an SMS to it with the appropiate command. It is a function that will save the day if someone steals the car keys and the remote to the immobilizer - like if you are being mugged or you forget to lock the car or turn on the immobilizer.

 

[jdub]

Cutting power to the ECU will dump all learned values, but in this case that's really not an issue. Have you considered wiring it to cut power to the fuel pump?

 

[Kristian_Wraae]

Yes, but I was affraid it might make the engine run lean for a short while before it would stop. But I guess it wouldn't be long enough to cause any damage.

 

[SySt]

Yes, but I was affraid it might make the engine run lean for a short while before it would stop. But I guess it wouldn't be long enough to cause any damage.

You would also lose ignition control so running lean would not really be a problem. If anything it would cause a very small amount of fuel into your oil...