MoTeC Global Forum

Hi

I'm racing in a series which includes a compulsory pit stop and (optionally) a driver change. I've taken advantage of the fact that the M4 provides a strategy of speed limiting based on a switch and this all in testing.

With the pit lane switch activated and above the pit lane speed, the engine and speed drops until the desired speed is reached. Once below the desired speed, I increase the throttle to maintain the pit lane speed and its here I get problems. If I use a very light throttle (less than 20% or so) I get a slight misfire which keeps the speed as desired, however if I use too much throttle I get a lot of sever jolting until I lift off.

My question is, is there any way of reducing this effect and making it smoother at slightly higher throttle loading ?

Naturally I don't expect it to be silk smooth at 100% throttle, but at a bit more than I have now, say up to 40 % TPS ?

Note that I also use normal rpm limiting, so whatever is done should still provide that function...

BTW The engine is a more or less standard 1600cc 4 cylinder with max rpm of 6400.

Cheers

Hi Turby,
You could try increasing the control range of the main RPM Limiter this will bring the cut in smoother BUT.....realistically you only need about 15hp if that to roll a car down a pit lane, if you foot is requesting 20hp the ECU only has to kill of 5hp, if you ask for 120hp the ECU has to kill off 105hp. The best thing to do is not request so much power. With a 4 cylinder you can only cut 1, 2, 3 or 4 cylinders, think of it like 25% resolution on the cut, this basically means the jolting can't be smoothed out much, if you had more cylinders it would be better.

Had the same problem with the V8 Supercar guys always pushing the throttle through the firewall thinking 40km/hr was faster when the throttle was all the way down, all it does is make the cut really harsh and fire big flames out the exhaust setting poor unsuspecting MoTeC track support staff on fire.....thankyou very much Mr Bowe.