Winfred/bill: Power after key removed?

[Jon K]

Thanks - still trying to figure out why my car is running when I remove the key!

It's like the MegaSquirt ECU is still getting power for about 5 seconds when key is removed and it doesnt just shut off, it like sputters out.

I have the power source for the GM coil pack and the MegaSquirt coming off of the Main relay... what gives!?

[winfred]

something may be back feeding power and keeping the relay powered, sounds like you are killing it with the fuel pump, id be looking at how the main relay reacts with a test light when the key is killed

[Bill R.]

dme keeps the main relay turned on for 3 seconds after shutdown to avoid what they call post ignition.




Thanks - still trying to figure out why my car is running when I remove the key!

It's like the MegaSquirt ECU is still getting power for about 5 seconds when key is removed and it doesnt just shut off, it like sputters out.

I have the power source for the GM coil pack and the MegaSquirt coming off of the Main relay... what gives!?

[Jon K]

dme keeps the main relay turned on for 3 seconds after shutdown to avoid what they call post ignition.


Thanks guys - yeah I am powering the MS ecu and the coil pack off the main relay. So should I move it over to the fuel pump relay? Does that relay cut off with the ignition?

[Jon K]

dme keeps the main relay turned on for 3 seconds after shutdown to avoid what they call post ignition.


Bill - how come, then, does the car like die out rather than cut if it shuts off after 3 seconds? I could deal with it just dropping after 3 seconds but it runs REAL rough like fuel pump is turned off and the car is sputtering down.

[Bill R.]

stock dme cuts off the injector pulses as soon as you turn the key off ,effectively cutting the fuel supply to the cylinders, while the main relay is still powered up and igniting the coils to burn off any remaining fuel in the cylinders before the engine comes to a stop. I have no idea how your system is doing it.

The stock fuel pump turns on for a short period of time when the key is turned on and then it runs continously when the crank position sensor reads that the engine rpm is greater than 150rpm. This way if the engine stalls but the key is still on, the dme senses that the crank isn't moving and shuts the fuel pump off. Now i think on key shutdown the dme turns the fuel pump off immediately.





Bill - how come, then, does the car like die out rather than cut if it shuts off after 3 seconds? I could deal with it just dropping after 3 seconds but it runs REAL rough like fuel pump is turned off and the car is sputtering down.

[Jon K]

So my best bet would be to run a relay that is triggered by the ignition circuit so that it closes with the key but opens with the key as well. Is there a wire that is triggered in the E-box that I can use as the trigger for the new relay?