Ok guys this is a bit of a retarded question considering that I have an Apexi AVC-R fitted in my car.....But it would be much appreciated if someone could explain the difference between the two: On the AVC-R its got two adjustments under the "boost setting" 1. Boost 2. Duty What is the specific difference between the two? Last time I got the car tuned the mechanic tuned it all well, but I just like to know this for my own interests sake. For instance, what would be the difference say if you have 1.) 1 BAR boost with 50% duty? 2.) 1 BAR boost with 100% duty?
Boost is obviously your manifold positive pressure indication and the setting you desire for boost pressure to reach. Duty is the percentage the boost control solenoid cycles (opens and closes). If the duty is set too high, the boost will likely over shoot the desired pressure setting, too low and boost will fall short of the desired boost setting. The great thing about the AVC-R is the ability to self learn the duty cycle. All you need to do is some sharp short bursts to see where the boost is reaching and adjust the duty cycle accordingly until the boost is close to the desired boost pressure. Do a couple more runs and the duty cycle setting will go into self learn which is indicated by three stars (***). Please not this will only work if the RPM wire has been spliced into the revolution signal wire into the ECU. The alternate configuration is into the injector feed which will show injector duty cycle but at the cost of forfeiting boost duty self learn.
Thanks chief, That actually does clear up a lot of the confusion. Do you have any idea as to now I can check how the wiring has been set on the car - cause I didn't do it myself ? it came with the car. I mean, is there any way on the actual controller you can do this? But per you reply, it does have the (***) setting on there at the moment. So I guess I'll just drive it around it until the unti gets used the car eh? Cause as it stands now, I've got the boost set to 1.05bar and the duty on (***). On inspection of the graph it shows that the duty is set around 50-60% and then it shoots up once you reach higher revs. But the thing is this.....on my dyno run it shows that the boost slowly starts to leak once it hits the 1.05 bar mark. So in another word, it doesn't hold at the set level. Would this be something to do with the duty setting or is it more a physical thing like one of your vacuum pipes coming loose?
I don't know what sort of setup you have but do you have a aftermarket IC? If your still on a stock, the boost 'leak' is probably the intercoolers not being big enough to cool the air. I'd say 1.05 bar is around the limit of the stockers in the 300, give or take a little. Don't know about the AVC-R duty cycle, sorry.
Thanks man, I think you are right there about the limits of the stock turbos. But really I need to know what the difference is between the two settings I prescribed earlier. I.e. 1.) 1bar with 50% duty 2.) 1bar with 100% duty What would be the difference between the two? Anyone know at all? I mean, what exactly does the above to setting mean and how would they effect the performance (preferably the horsepower) of the car? Any help would be much appreciated. Cheers.
I meant the stock intercoolers. The stock turbos would be good for a fair bit higher I'd say. The stock intercoolers just can't wash off the heat at that sort of boost. From what I read above by 90TTZ: 1.) your running 1 bar with the solenoid cycling half way then closed again. 2.) your running 1 bar with the solenoid cycling fully open then closed again. I don't think it would effect performance at all. Your still running one bar. The duty cycle would be there as for different boost levels you'd want to have the solenoid opening diff amounts for efficiency. The only way it would affect performance would be if opening 100% caused some boost leak etc. or vise versa with 50% if that makes sense. At least thats what I'm interpreting.
An explanation..... Think about it like a tap connected to a water system. The duty cycle is determining how much pressurised substance the tap will let through. In this case the tap is a vent of boost pressure away from the wastegate actuator(s). So at 0% duty cycle, the solenoid is doing nothing, and 100% boost pressure from the turbos will reach the actuators. The stock wastegate actuators have a diaphram spring pressure rating of around 7psi. When 7psi is applied to the diaphram the wastegate opens, hopefully ceasing any further rise in boost pressure. The bleeder solenoid connected between your actuators and positive pressure has an operating voltage range that is represented inside the controller as 0 to 100%. At 0% it's inactive, at 100% it should theoretically be bleeding all positive pressure from the actuator pressure lines (however, this may vary from controller to controller). The AVC-R works on a principal of fuzzy logic. It does boost control "on the fly", so to speak - by getting quick feedback from its digital pressure sensor. The first thing you do is tell it what level of pressure you want to achieve. The second duty cycle setting is a rough initial value that you should program in. To find this value, experiment with it until you find the point where at a full throttle run, you come as close as possible to reaching your desired boost pressure WITHOUT exceeding it. After you set the initial duty cycle, you then need to do a full throttle run (any gear, I use 2nd so as not to break too many speed limits) that goes all the way from your lower RPM range to your higher RPM range. I think on my AVC-R I have the range set from 3000 RPM to 6500. Once you've done this run the AVC-R will have learnt (via fuzzy logic) the duty cycle per 500 rpm increment required to keep the boost steady at your set value. When this self learn is complete the duty cycle will appear at ***. If needed you can go into the *** and you can adjust the per-rpm duty cycles if self learn isn't doing a good job. To answer your last question: 1 bar at 50% duty cycle: You will probably undershoot your desired boost setting of 1 bar until the fuzzy logic corrects it 1 bar at 100% duty cycle: You will probably overshoot your desired boost setting of 1 bar until the fuzzy logic corrects it That should cover you.
