- Mover -

I monitor real time data of my engine operation sometimes with the icarsoft.

Sometimes I watch the switch from short to long intake runner and know how to activate the switch myself while driving. This isn't a problem.

The swirl/tumble flaps are another story.
The swirl/tumble flaps are monitored by sensors at the back of the engine and give off a voltage reading to icarsoft.

At rest with no vacuum applied to valve, the tumble flaps are not activated and the voltage reading is approx 5 volts.
When vacuum is applied to the value, the tumble flaps are activated and move into the intake runners. Voltage reading is almost 0 volts.

The problem is, I almost never see the tumble flaps activated. I've seen them activated on cold start briefly and when closing the throttle from high rpm at times. I've come across a chart which shows when they should/shouldn't be activated, but the chart and how mine are working don't match. Also, I don't have any engine codes being thrown.

Does anyone have any further information on when the flaps are active/not active ?

cetialpha5

I thought the point of them were for engine performance at low and high rpm. I guess if you drive conservatively and don't get the revs up, then maybe they don't switch. If you search the old threads on the intake manifold, you'll find that it takes a while without the flaps opening to set a code and I think others have noticed problems like the broken lever or some other problem with the intake and a code hadn't been set yet.

Mud

The flaps may be partially stuck and may not throw a code yet. You can apply vacuum to the control canisters on the intake and see if all levers move freely and fully.
As mentioned, the levers and/or lever arms can break.
One cause of jammed flaps is excessive oil coking onto the components. Check the pcv cannister (also called an oil separator) on the back of the passenger side cylinder head. The tube from that round canister to the throttle body should at most just have a very light trace of oil inside it. Oil dripping or pooling in that tube indicate failed canister.

- Mover -

Looked into this further. The above makes sense.
The intake air is tumbled to produce a stratified charge at startup.

Does this engine (M273) have a true stratified charge running mode or is the intake air direction (tumble) only being modified ?