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Discussion and questions related to the course Introduction to Engine Tuning
While dialing in the cam control base duty, the angle managed to get to 50 degree. Does anyone knows if that is possible? For elite 2500 on suzuki swift sport. I have read through the tuning courses and noticed that most cam control max out at 30ish degree. How the cam angle table corelate to the actual cam angle. Am i right to say if my maximum achievable angle is 50 degree, in order to get the cam at neutral position i have to set the table at 25 degree? Hope someone can point me at the right direction.
usually the cam' angles are in crankshaft degrees, so half what the degrees would suggest.
I'm not familiar with the engine, but that seems a little on the high side - have you any information on the OEM operating range?
From the service manual i believe its 60 degree from full retard to full advance. But from OBDII, it only show the vvt difference. I'm not able to know the exact angle. Is there anyway to find out that angle? From the service manual it looks like the cam signal is pulsing. I'm kinda lost in all these information.
The manual is showing you the duty cycle of the oil control solenoid. That is probably showing you the condition that requests the input cam go to full retard in preparation for starting the engine. You ECU should be able to measure the cam angle using the Cam Position Sensor. So that's where you got the "50 degrees" from -- the ECU measured it.
which means 0 in the table is full retard and any number that i keyed in will be the angle that the ecu will be trying to reach? Am i right to say if i wan it to be in neutral position, i have to key in 25ish because i could see 50 degree as the maximum degree.
Usually the table represents the desired cam angle, and varies from 0 to near the maximum advance the VVT mechanism capable of achieving.
Generally neutral with an oil valve means a duty cycle value that will basically hold the position steady - values above this move the cam in one direction, and below move the cam in the other direction. Generally they need PID control to hold the Cam at specific angle, as the value is not constant over temperature and oil pressure variations.
David. I think I sort of got the idea. I was trying to dial in the base map yesterday and realised that the cam angle affects VE table. It's more prominent during move off. How do you find the 'right' angle for a smoother move off? By trial and error?
David, I have seen these but it's the moving off part when on the road. Around 900rpm to 1100rpm ( - 20kpa) which I am finding difficulty to tune.
I would try carefully documented experiments. There are only three results possible -- better, worse or the same. Figure out which result you are achieving, and with enough experiments you will find a direction, and be able to optimize the result.
My starting point would be to use full retard at idle, and determine the ideal at 2000 RPM at the lowest throttle possible, and 2000 RPM at full throttle. Then make a smooth curve of the cam position between those points. Keep changes to the cam position limited to less than 2 degrees per 100 RPM, so it never changes too quickly with increasing speed.
You may find that ignition timing has more effect on the "feel" of an engine as it "moves off". Another possible "move off" issue -- you may have an idle control system that is trying to control the engine, when you are trying to apply more power.
Alright.i will try towards that direction.