Thread: Stalling a turbo during runaway shutdown

Assuming there are no problems, at least initially I'll be making these available for basically the component and postage cost which is expected to be around $60, but double for a 3.6 TDV8. The cutting and joining of the throttle motor wires makes them not plug-and-play but for long-term peace of mind I consider it worth having for vehicles no longer covered by a warranty that includes engine destruction caused by a turbo failure.

The pcb is fitted with a test ignition switch to allow easy confirmation, without having to switch on the ignition, that the throttle motor wires are connected correctly by sighting the butterfly closing after releasing the switch. If the butterfly doesn't close then just swap 2 plugs around. A LED on the pcb shows when the DPDT relay coil is energised. If the butterfly doesn't re-open when the LED goes off then press the inner side of the butterfly to make it open then clean the intake housing where the butterfly contacts. This sticking shouldn't subsequently occur because the butterfly will be closed at every ignition off, keeping the contact area clean. The default relay position leaves the throttle motor connected to the pcm, hence disconnecting the power plug from the module renders in inert. Switching on the ignition will cancel the close operation if it was still in progress, without regard to whether the engine is being restarted or not.

I feel this is a better solution than having to react to an engine runaway by removing the air intake hose in a safe and timely manner, being mindful that even lifting the bonnet could be life-threatening if engine parts start flying. Removing the throttle air intake hose from the I/C would deprive the engine of the oil from the turbo so should be enough to stop the engine without having to block the intake, assuming that the oil is indeed escaping from a turbo rather than some other internal source such as valve stems.

A throttle closer is now also fitted to Justin's 3.0 D4. The throttle motor wires were intercepted near the throttle motor connector rather than at the ecm because of the difficulty in accessing the ecm harness and easy access next to the throttle body. If the engine harness has to be removed then the lead to the throttle closer box can be unplugged from the box to stay with the engine harness. Ignition power was obtained from wiring for the transfer case module and permanent 12V power from a small fuse panel previously installed near the brake module.

The engine seems to stop slightly more abruptly from idle than previously. No faults occur.

Installation on my brother's 3.6 RRS wont occur until mid January.