MoTeC Global Forum

I have a Greddy Dual valve unit. Can you tell me what the proper parameters to use for this valve on my M4? Right now I am having boost surge and fluctuations at higher RPMs. Boost is just not very stable.

Need more info, what sort of waste gate set up? how is it and the solenoid plumbed? what engine? Preferably post your map and a log showing the issue also.

Waste gate is an external unit. It's plumbed for operation from the turbo compressor outlet to the diaphragm of the waste gate. The control valve is plumbed from the intake (after the throttle body) thru the Valve and to the inlet side of the waste gate diaphragm. Engine is 13B Rotary. Don't know how to save or create a log, sorry.

I currently have the control valve being operated from Aux Output 1. Current settings are as follows:

Gain 30
Derivative 20
Ave. Pos. 40
Type 2
Frequency 20
Min Cycle 10
Max. cycle 90

I'm not 100% clear from the description of your plumbing, but if your solenoid is a normally closed type and the hoses are connected so that it pressurises the top chamber of your wastegate when "turned on" then your "type" setting is wrong, should be #1, not #2.

Sorry for leaving that info out. The valve is open when not powered. When the valve is off, the backside of the waste gate diaphragm gets pressure thus increasing the boost. I'm not understanding why I hear the control valve clicking when I touch the throttle slightly and when I give a little more throttle the valve seems to quite down. "The boost also fluctuates at higher boost levels (9-10 psi). I plan on running 15-17 when fully tuned. If I have the settings correct, do I just need to do more tweeking?

isn't there anyone out there that has knowledge of the valve I have? I need to know if I have the correct frequency and min/max duration settings.

kevin6989 wrote:isn't there anyone out there that has knowledge of the valve I have? I need to know if I have the correct frequency and min/max duration settings.

Google images doesn't even give any hits if I search "greedy dual valve" so maybe a part number would help identify what it is...
I'm any case your settings don't look a million miles away, assuming your valve is based on a typical boost control solenoid. I would bump frequency up to 30, set min to 20%, max to 80%, and set derivative to 0. Start with a low gain and adjust it up in small steps until you get some reasonably steady control when engine is under relatively steady load. From there you can tweak D and other settings until transient control is acceptable.

AdamW, I'll give that the ol' college try and get back to you later. I did watch one of the Motec Webinars for boost control setup. Pretty good info there. I ended up re-plumbing the boost valve. Thanks for the info and help.

It seems from pictures online that that valve only has two ports? - or is there maybe a bleed port hidden inside the case? Perhaps you can open it up and take a look inside? If it really has just two ports it wont work how you originally had it connected - you will need a bleed somewhere in the system.

AdamW,
It does have the bleed port. Inside the box there are two (dual) valves hooked together with manifolds. This allows twice as much flow thru the valve to give quicker response of the boost control.
BTW, I made a change to Duty Cycle control of the valve and the boost is now more steady and controllable. The next step will be moving to PID control once I have my fuel map better tuned.
More to come as the tuning progress'.