Thread: Stalling a turbo during runaway shutdown

Dumping a Co2 extinguisher into the air intake is my strategy.
A Iveco Daily 4x4 twin turbo ran away a few weeks ago. seized & destroyed . The 3.0 F1C Iveco engine indeed has a TVA (throttle valve) (independent of EGR) which closes with IGN off - but it did diddly squat to stop the runaway .

How well did the TVA seal? My 4.4's is very close-fitting, closing firmly against the housing and the butterfly on my then TD5 D2 sealed well enough to choke the engine immediately it closed.

if its running away, taking your time to choke the air supply is likely to allow the opporutnity for more damage than just slamming it shut.

Its not going to instantly stop and the crankcase ventilation system should be venting the excess crank case pressure, if the turbo seals are the only failure take it as a win.

Got me thinking , An Oil shutoff valve in the Turbo feed may be better than trying to choke the air intake. ??

If the facility goes wrong then no air is much less of an evil than no oil to the turbos.

I have a day or 2 to cool my heals while the canola dries out more so hope to get the wiring installed to start real-time testing, albeit at far less revs and without an oil supply directly into the inlet stream than during a runaway.

Originally Posted by Blknight.aus

if its running away, taking your time to choke the air supply is likely to allow the opporutnity for more damage than just slamming it shut.

I have allowed for a soft closing of the butterfly because it will be shut at every IGN off and didn't want to risk damaging the throttle motor and mechanism. A test on a spare 3.0 throttle body applying 13.5V for many minutes showed that the motor can withstand such voltage. My testing with the 4.4's butterfly showed that only 50% duty cycle @ 400 Hz at 12.5V closes the butterfly firmly, but currently softened with 2 seconds @ 40% duty so takes 3 seconds to fully close then stays closed for 9 more seconds, on the basis that the engine would have stopped well before this time. If more time is considered worthwhile then the only drawback for everyday use is a little more power consumed for the extra time.
I may at least remove the stage 1 softer closing as at 50% duty it still takes about 1 second to close. I'll remove the half second initial wait if the pcm doesn't object to the butterfly motor being disconnected the moment the IGN goes off.

What about a Dump valve, dump the turbo pressure , then TVA ??

I think that closing the butterfly under normal shutdown with an engine already idling shouldn't cause any problems due to residual turbo pressure. IMO its intrusive enough to do the electrical work without adding a device to the air intake system to handle a situation that one hopes will never occur with their engine.

The TDV6 butterfly motor fitted to the 2.7 and 3.0 engines is directly-coupled to the butterfly and requires more than 95% duty cycle @ 400Hz to close. As this causes the switching FET to quickly get quite hot, for these engines a full 12V will be applied. The butterfly doesn't unduly slam on full voltage.

The 3.6 TDV8 has 2 throttle bodies with a geared butterfly similar to the 4.4 TDV8. A brother has a 3.6 RRS so I'll enlist his help in testing butterfly operation on these engines. 2 modules will be needed.

The original pcb caters for 3-post header and associated resistors to provide 3 different close options using a single jumper. I have 30 pcbs with several already allocated and will get more if required.