Boost control / slippage

[fphil]

Is there a way to limit the boost whenever a fast variation of RPM  indicating slippage occurs?

[VEMS]

Hello Phil,

Yes, use anytrim based on absolute or relative difference between driven and non-driven wheel to adjust boost target, this said; it is more effective to trim ignition advance, as boost target trim (and the time it takes to reduce the actual boost) induces some lag.

Best regards, Dave

[fphil]

Hello Dave,

I have just suceeded to get into Vems the propshaft speed as seen by the car Jaeger sensor (I should do a wiki report about) and I do not have both driven and non-driven wheel speeds. So I was thinking of the possibility to limit the boost /torque when detected a too fast variation of RPM.

Regards

Philippe

[mads b (dk)]

How will you make this work in all gears?

Rpm changes in 1. gear is much faster then higher gears ?

[fphil]

from the propshaft speed one knows which gear, no?

[VEMS]

Hello Phillipe,

So I was thinking of the possibility to limit the boost /torque when detected a too fast variation of RPM.

RPM derivative based boost trimming is not available (as you know) nor planned. IMHO it will be a nightmare to detect what causes the swift rpm up can be wheel-spin, but also clutch pressed throttle blip or other outliers; My suggestion mount 2 additional wheel-speed sensors (perhaps the ABS rings sensors can be tapped or retrofitted) ?

Best regards, Dave

[fphil]

Yes Dave you are probably right about the nightmare. Better to fit additional speed sensor (this 1987 car does not get abs) which would give straight information or else keep happy with the acceleration slippage 
Regards
Philippe

[gunni]

Hello Phillipe,

So I was thinking of the possibility to limit the boost /torque when detected a too fast variation of RPM.

RPM derivative based boost trimming is not available (as you know) nor planned. IMHO it will be a nightmare to detect what causes the swift rpm up can be wheel-spin, but also clutch pressed throttle blip or other outliers; My suggestion mount 2 additional wheel-speed sensors (perhaps the ABS rings sensors can be tapped or retrofitted) ?

Best regards, Dave

How do you get two wheelspeed into the vems for control?

[VEMS]

Hello Gunni,

How do you get two wheelspeed into the vems for control?

Ordering the ecu with two wheelspeed inputs and wiring it up (externally to non driven wheel for wheelspeed #2) does the trick.

For retrofitting see (hardware version v3.7 or lower): http://www.vems.hu/wiki/index.php?page=InputTrigger%2FWheelSpeed the circuit normally fitted to wheelspeed #1 need to be copied and connected to SCL pin. From v3.8 HW and up this circuit is already on-board and only needs a wire from the pcb to the free ec18 pin you want to allocate for it.

Best regards, Dave