New Boostcontrol strategy allows even easier configuration: since 1.2.9, see BoostcontrolWithTargetBasedReference

Boostroncol in 1.1.67

up to 2 independent PWM outputs (driving wastegate bottom and top chamber, or completely different usage):

Dutycycle table suggestion

After trying to tune the current (1.0.36) firmware PID BoostControl, I realized that it's hard to tune.

Tried different methods and PID settings, but never got a really satisfying bahaviour => write on your page:

In this case filenames are referring Period_P_I_D settings!


Openloop actually means that MAP is NOT used. In general control requires to consider the controlled variable (MAP), that makes it closed-loop.

Any of the mentioned open and closed loop setups are possible with VEMS, including 2 separate outputs with different strategies.

So openloop turbo boost control is available, but most actually want closed-loop (even when saying openloop).

A "force boost solenoid duty" command would be nice to make boost system measurements (and tuning) easier.

In the meantime

After doing (logged!) runs (which gear ?) with forced duty increased a little every time, an analysis (result can be like: +10% duty raised max reached boost by 20kPa or similar) can help to get good initial values for P (and likely I and D as well).

Overview of boostcontrol

Typical Pneumatic connections

Boost control system layout:

Primary system for internal wastgate:

Primary system for external wastgate:

Improved spoolup and range for external wastegate:

The systems are sequenced, first pressure is applied to the top chamber but if that is not enough (remember EBP pushing on the wastegate valve) the boost control working on the lower chamber will start to bleed off boost. In addition to this the system acting on the bottom chamber is always bleeding off as much boost as possible until the system is getting over the adjustable 'spoolup' threshold.

Note that the atmosphere connection can be replaced with a vacuum connection. A vacuum reservoir will NOT work, it has to be a fairly high capacity vacuum pump. (If a zero break pressure check valve is found and used (never seen one) to atmosphere a vaccum reservoir can be used.)


Audi external wastegate example - under investigation, no final word on this yet; Actually, text below might be bad ! Please review


Is this (trying to be) similar as the "boostvalveexternal" example connection ? - Yes, I was wondering if this was the best solution.

Operation - must be verified against the connection


The alternative would be to put the solenoid in between the compressor and the bottom chamber (big pipe), like a regular boost control and let the top chamber vent to atmosphere.


Solenoid would only be powered when boost needs to be regulated which is better because with the other configuration the valve would be powered constantly at idle and cruising, not very good.(unless there are different types of solenoid valves? i.e ones that would vent to atmosphere when powered)

Possible Cons:

Very slight loss in performance due to bleeding off boost, the other configuration would theoretically not bleed any boost(not bleeding off boost could cause a problem with the wastegate returning to closed state). Possibly slightly slower actuation of the WG valve due to restriction in the solenoid valve.

After some thinking it seems to me like the regular boost controller style setup would be the best choice. Except I don't get this:

Primary system for external wastgate:

What would make this configuration spool up faster and have an extended range? (this is the config which the above section is about, not the alternative here) And from your text Jörgen it seems to me like the valve would vent to atmosphere in the unpowered(rest) state, contrary to Marcell's correction above.

And just to make clear, the bottom chamber (closest to the valve) is the one where boost would be applied to open the WG valve, top is the chamber with the spring in it and a higher pressure in this chamber would only keep the WG shut harder.

Honda VTEC / Toyota VVTI / BMW Vanos / etc... control

(the more complex type) is very similar to boost-control:

The simpler/older "single Vanos" basically only requires RPM dependent on-off output, no feedback and no PWM => can be implemented with misc1/misc2/wot or rpm actuator.

It seems possible to control the complex version with proper configuration of the boost-control code (or small firmware mods?) but this has yet to be proven.

Does the BMW double Vanos have feedback from the Vanos actuator (position) ?

See also