Adjusting Cruise Control
Discussion
Does anyone know if the dealer can change any parameters or if there is a factory fix for the rocking effect when going down a hill with cruise control engaged? Obviously the maths haven't been done right for the control system and the system is underdamped (overshoots). It's slightly irritating.
BingoBob said:
Does anyone know if the dealer can change any parameters or if there is a factory fix for the rocking effect when going down a hill with cruise control engaged? Obviously the maths haven't been done right for the control system and the system is underdamped (overshoots). It's slightly irritating.
The master of understatement. It is bloody annoying.....
Mine only seems to vary by +/1 1mph, which is good enough for me.
My Audi has adaptive cruise control, which applies the brakes if you go over the selected speed, which really annoys me. The Aston system isn't connected to the brakes, so doesn't intervene downhill, is that the problem you're describing.
My Audi has adaptive cruise control, which applies the brakes if you go over the selected speed, which really annoys me. The Aston system isn't connected to the brakes, so doesn't intervene downhill, is that the problem you're describing.
MichaelV8V said:
Mine only seems to vary by +/1 1mph, which is good enough for me.
My Audi has adaptive cruise control, which applies the brakes if you go over the selected speed, which really annoys me. The Aston system isn't connected to the brakes, so doesn't intervene downhill, is that the problem you're describing.
no it is the on / off throttle that makes the ride very jerky, rather than a feathered throttle that can be done easily with the right foot.My Audi has adaptive cruise control, which applies the brakes if you go over the selected speed, which really annoys me. The Aston system isn't connected to the brakes, so doesn't intervene downhill, is that the problem you're describing.
BingoBob said:
Does anyone know if the dealer can change any parameters
or if there is a factory fix for the rocking effect when going down a hill with cruise control engaged?
Dealers can't change parameters, they can only reprogram with what files the factory issues them with, and like any other matter ECU related re calibration is not possible unless factory lead.or if there is a factory fix for the rocking effect when going down a hill with cruise control engaged?
I would hazard a guess that you experience jerky cruise control because the coast-down adaptive learn value for flywheel based misfire detection has been lost. When the adaptive learn feature has been lost and engine has not seen conditions to enable an auto learn, a side effect is no fuel cut off in 6th gear during cruise control.
The adpative coast-down learn is there for the ECU system to understand normal engine running conditions in an attempt to easily identify an anomaly (misfire) by measuring acceleration between measured windows / flywheel position. The ECU fitted to this car has no volatile memory space meaning that when battery is drained or is disconnected any adaptive 'leans' or stored fault codes are lost. If the adpative learn conditions / cycles are not run (as they are when the car first rolled off the production line during initial test by factory around their track), certain side effects are encountered - poor control of speed setpoint during cruise is one of them.
Try forcing a learn cycle and see if the problem disappears, the reason why some forum members complain of bad control and others report no problems could be all the cars with the problem have lost their adaptive coast-down learn value, whilst all those who report no problem must have a coast-down learnt value still stored.
With all electrical loads switched off (headlamps, heater blower, internal lights, radio - EVERYTHING..!)accelerate to 70mph in 6th gear. Then come off the throttle and with no brake application or any change to the over-run condition, allow the engine / car to coast down to below 30mph remaining in 6th gear. Repeat this a couple of times to be sure, to be sure, and then see if the cruise control condition is altered. You will need a long empty road..!
Clearly steering is ok as is braking to avoid an accident..!
BamfordMike said:
...The ECU fitted to this car has no volatile memory space meaning that when battery is drained or is disconnected any adaptive 'leans' or stored fault codes are lost. ...
Excellent post and very logical reasoning.One correction - you meant "no non-volatile" memory in this bit (or "the ECU has only volatile memory space").
Volatile memory loses its contents when power is lost. Non-volatile does not
Murph7355 said:
Excellent post and very logical reasoning.
One correction - you meant "no non-volatile" memory in this bit (or "the ECU has only volatile memory space").
Volatile memory loses its contents when power is lost. Non-volatile does not
thanks you for the correction - yes, that's what i meant...!One correction - you meant "no non-volatile" memory in this bit (or "the ECU has only volatile memory space").
Volatile memory loses its contents when power is lost. Non-volatile does not
EU6 emissions legislation requires ECU hardware to have non-volatile memory because long term storage of adaption / learnt values is the new standard. The Aston ECU, at least pre Vanquish II has no non-volatile memory and together with lead being used in its construction (the solder) meant that the ECU was on the verge of being outlawed for EU6 cars and beyond without serious re-engineering. The importance of this and for us here is that any Aston pre Vanquish II requires some of the precise cycles to be repeated, as when the car was first built, if the battery is ever drained or disconnected to re-learn important stuff which is required to enable other things - In this instance correct control of fuel cut and reinstatement during speed setpoint control in cruise mode.
Of course, this might not be the OP's problem but would be my starter for 10 before any other work was undertaken to find the cause.
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