Powershift set-up issues

Powershift set-up issues

Question:

One of our trade customers was having problems with a powershift set-up on one of their customers cars and asked for some help, he had set up the map using the settings from another car which has worked well.

The car was an Escort with a VX and Elite IL300 box and the description of the symptoms was; “Just been out in the car and it still isn’t working correctly, it’s very harsh when it comes back on power, not a nice smooth cut at all. It all seems too harsh and needs smoothing out. The setup is just using an ignition cut, cutting the spark, so it’s very on and off. The setup allows for torque reduction + recovery, can you tell me a bit more about these settings and also why these aren’t been used? There isn’t any information available about the MBE settings and if I fiddle with them without knowing their functions, it will end up causing issues.”

He also asked: When we have spoken in the past you said you had not found the need to use the torque recovery and that ignition only worked very well. Hence my using the same options. Could you provide any advice as to possible solutions. I notice on the paddle shift set ups I have looked at the “Finish Upshift Drum Rotation Threshold” is at 70% but on the flatshifts its 100% – could this be the issue?

Answer:

Always make sure you are using the latest software, please check our website.

I suspect you have 2 potential issues; the first problem will be how the power shift is triggered. Quite often some of the gearboxes have an adjustable switch or sensor and what the manufacturer quite often does to ensure the powershift works is to make the switch trigger too early. This means that when the gearstick is pulled that instead of triggering just at the point of disengagement, it is triggered much earlier, this effects both single cut time set ups and full closed loop set ups. When used in the single cut time, it means that the time has to be extended to cover the fact that when the driver pulls the gearstick, there can be quite a length of time from the spark being cut before the dogs of the gearbox are actually disengaging and by the time the gearbox has completed its change, the driver will be able to feel this huge delay making for quite often and uncomfortable gear change. When using the closed loop version the same issue applies, the trigger again will be too early and although the gear change time is able to vary due to the ECU knowing the drum position and able to complete the gear change when it reaches a pre-programmed position, it is extended due to the early trigger.

In order to alter the trigger point, you will need to discuss with the manufacturer of the gearbox how this is done and experiment with the trigger point according to the manufacturer’s instructions. This could be done by shims or adjustable screw to move the switch.

Once you have sorted the start point, then you will be able to adjust the cut time if using a single cut set up but because no gear changes are ever the same, care must be taken not to shorten the cut time too much. A single cut is also not suitable for cars that could potentially be wheel spinning during gear change. It is always best to use closed loop set up using the trigger to initiate the gear change and drum rotation to complete the gear change. This way the MBE system self-adjusts to the variation in time taken for each gear change.

Due to the fact that every manufacturer of gearbox works slightly differently, therefore the gears drum rotation will also vary. You should experiment with the percentage of drum rotation for completing the gear change. When set to 100%, the power will only re-instated once the gearbox drum has completed its rotation. You can experiment with shortening this value and it will speed up the gear change. Again great care must be taken if the value is set too low, although the gear change would become very fast, if the dogs have only just engaged there is a possibility that damage will occur due to the fact that the power is being re-instated too early. We find that most car gearboxes can go down to 70% of drum rotation and bike gearboxes down to 79%, but it is suggested that you start at 100% and slowly reduce this value due testing. The difference between cut and retard; cut simply removes all the sparks and retard will retard the ignition so the engine produces no power. Cut is simpler and if all the above are set up correctly, the gear changes should be very nice. If you use retard, it can be smoother but produces other issues; whilst retarded the engine will be producing more heat and if the engine itself is prone to any issues, it could amplify an inherent problem with the engine. Also when the ignition is in a retarded state, the fuel is no longer ignited in the combustion chamber, it will be ignited in the exhaust producing additional noise because of this. A combination of cut and retard can be used but more information, as far as suggested settings are concerning, are within Easimap 6.