Hey All

I have a parasitic drain I am trying to troubleshoot. Battery drains down in a week with key off and locked. At one point I had shut the engine off and there was a noise that sounded like an electric tire pump going crazy. Ignition was off. I couldn't see the part at that time but I could feel the vibration in a hose leading to the front of the intake. Later I traced it back and found what looks like some kind of solenoid under the intake. It has a wire plunged into it and a hose coming out the back side. Does anyone know what this is. Remember this is a three rotor.

 

How old is the battery? Have you done a load test on the battery?

 

That component looks like it may be an external idle air control valve.

If so, it should have a hose leading to it from in front of the throttlebody and a hose leading to it from after the throttle body on the intake.

This would make sense on why the hose would vibrate at idle as well (solenoid pulses to regulate airflow/idle).

 

I didn't do a load test on the battery. Don't know how to do that. I did disconnect the battery for a week. That is how long it usually takes for the battery to drain till dead. When I reconnected it and hooked it up to the charger, it read full, so it hadn't lost any power while not hooked up to the car.

Idle solenoid

Wondering is that is a stock FD3s part or if that needs to be sourced from a Cosmos.

 

I looked at some shop manuals. A part that looks to be in the same location is call a double throttle air control valve. Could that be the bugger? If it is, I don't know if that is a FD3S part. Since it is hooked up to a three rotor intake, It could be a cosmos part. Any thoughts guys? Thanks for the help.

 

Nothing stock looking about the installation or the piece.

Looks like a Bosch BMW 3 series idle air control valve to me.

 

If you think it's this part, you could always disconnect power to it when not running. If your battery still drains, it's not the cause.

 

Definitely an aftermarket part and probably a red herring.

What ecu are you running? It's pretty common for modified FDs to have battery drains, many owners use a Battery Tender while the car is in the garage so you won't have any issues.

 

You can usually narrow it down by just putting a volt meter in series with the battery (with the key off) and start pulling fuses until the drain goes away.

 

Thanks for the advice SGT Blue. Thats a pretty straight forward way to determine the battery drain. To Goodfella FD3S --- my engine management system is an AEM Infinity 6.