rotational idle on m4

[salsol]

can this be achieved?

[OmarK]

Hi Sasol,

We call this idle RPM and its an adjustable parameter in the Overrun Boost (Anti-Lag) Function in the software.

[salsol]

yeah i see the idle RPM, but the adjustments are only for the idle speed...i dont see anything for rotational idle.....I am using overrun boost mode 2....mode 1 does not allow the idle rpm adjustments.....

[OmarK]

Hi,

Could you please explain your definition of rotational idle?

[salsol]

Rotational idle has more to do with quickly cooling the engine as running a car with antilag causes very high temps to be achieved when antilag is on. When rotational idle is running the fuel mixture is much richer than needed to maintain a normal idle. This extra fuelling brings down temps quickly and rotationally dropping ignition of cylinders also further reduces temps as the fuel mixture is not burned but just pumped out of the engine unburnt.

[MarkMc]

Hello Salsol,
Our Low end RPM limit for the Anti-Lag is the function you are looking for, we just don't call it Rotational Idle. But there are probably a couple of things to clarify.

When you run a car with anti-lag (especially Group N cars) the throttle body is usually held open all the time, obviously this will mean the idle speed is excessively high. In order to keep a check on the idle speed the "rotational idle" function is used. Below a set throttle position the ECU will cut fuel (not ignition) to random cylinders so they make no power and therefore the idle speed comes down. The side effect is you are pumping fresh air through cylinders and the engine can run cooler. I would be suprised if any rotational idle system cut ignition and allowed fuel to build up in the exhaust system when you want the car idling, this would genreally lead to some rather unwanted explosions and fires.

Ironically enough this is the exact opposite of when the anti-lag is on where you do want the explosions and fire but this is at high RPM. On anti-lag with high RPM you cut the ignition and add fuel to get the energy in the exhaust to keep the turbo spinning.

[salsol]

oh...ok i got it working in the car......another question....I am running mode 2 anti lag, and these are my cut and retard tables..... and what it does.....its that it gives me a single very loud POP at about 2500 rpm after been run hard...with no throttle.....but I would like for it to be instantaneous as I lift throttle to change gear......I dont know what is wrong with the setting.....maybe you guys can help

[MarkMc]

Hi Salsol,
Your settings basically look fine, have you been testing this by driving or just free reving it in the workshop? Can you send me some data logging (send to mark.mccoy@motec.com.au).

[salsol]

i have been driving it, it exhibits the same behaviour driving and on the shop...only logging info i have right now is of workshop data, wont be able to drive it until tomorrow....I will log it then and send you the file, I will send you the free revving ones so you can look at those......thanks

[jasaircraft]

hi was this issue solved? what country are you guys running at? maybe I can help.