Hey guys.. Here it is.. a first look at the closed-loop boost control solenoid with overboost protection.. It has a 1-way valve to prevent vacuum from passing through the system (and basically reducing the vacuum signal to the component you spliced into, usually the DV/BOV)

Under boost, it opens the valve, and will pass through the solenoid, if the solenoid is 100% closed, the MBC will bypass the pressure at (in my case 22psi) but it can be adjusted..

The reason I did this is you can still remove the UTEC and never get obscene overboost.. but you get closed loop control, which means aggressive boost ramp, spike control, and faster spoolup.. Plus its less prone to issues that a bleed system would get.. (Air density and other factors)

 

Ok.. This is intended to be used with the UTEC closed loop boost control.. However it will work with anything that controls the stock boost solenoid, and even better if it controls the duty cycle of the stock solenoid.

at 100% duty cycle, you will get boost levels that you set with the MBC..

To use this with the UTEC in closed loop mode, you need a MAP sensor kit since closed loop control uses a boost target, and not a solenoid duty cycle..

But I wanted to share a new toy.. This setup allows you to convert any restrictor (checkball) type MBC to work with the factory ECU..

Keep in mind with the solenoid disabled, you get WASTEGATE pressure.. so a flash would need to use duty cycle (which I'm not certain is possible)

This mod will work with the UTEC, XEDE, AUTRONIC.. Anything that has duty cycle control of the stock solenoid can use this thing..

 

Sweeeeeet. What MAP Sensor are you using? GM?

I like your innovation.

 

GM 3Bar Map sensor.. I posted the part #'s in another thread around here somewhere..

 

Okalee dokalee, Jack. How long do you think that check valve is going to last in the blazing inferno underneath your bonnet? I wonder if you can find a brass version...hmmmmm. Also, those little plastic thingies can't hold a tremendous amout of reverse pressure. Give it a shot...let us know how it goes.

-chris

 

Umm, that is an industrial check valve designed for high temp environments, its vacuum rated at twice the vacuum the engine produces and boost pressures of over 30psi.. No soup for you!

 

Jack, where do you splice in to get a boost source? I originally spliced in by the BOV which worked ok but I was dropping around 5 psi boost by redline. I tried it on the turbo compressor boost source and now the boost is jumping all over the place and I spike at over 1.6bar every now and then.

 

If you can use the original location on the compressor outlet, you can get stable boost with a system like this.. Its essentially the same as a regular MBC would function.. the trick is to leverage the closed loop features in the UTEC.. The advantage is if you want to use the open loop, the solenoid will control your boost level until the duty cycle (and restriction) exceeds the pressure setting in the MBC..

I noticed the same thing when T'd off the BOV line.. when I removed the restrictor on the solenoid and installed the ABC (and used 4mm line) it stabilized around 19psi and didn't drop as much.. the big problem is its a bleed system, so to get higher boost you need to bleed off a little more using the ABC.. I pretty much left it alone because it gives me 18.5psi at redline and adjust my boost map to maintain more or less 20psi with a .5psi spike.

With the new solenoid and setup, if you cut off the signal to the wastegate, you'll just overboost.. so the MBC is a safety measure.. but you would end up with more control plus a bit faster spool..

 

That's the answer I was looking for...

 

Is that the GM solenoid or the stock one. If its the GM have you had any luck matching the resistance?

 

Yes, its the GM solenoid from the Syclone.. I have to find a resistor, but it actually works without it, I'm just concerned that the extra current might burn it out.. (It seems to actuate at about 9v) The CEL has not come on, but I suspect its because the UTEC is controlling the signal to the stock ECU.. I'll bet that the CEL would be triggered if I removed the UTEC. So until I can match the impedence of the stock solenoid, I'd have to live with it if it shows.. I am concerned that it may damage the driver so I chose not to leave it in until I get the resistor set up. My dad is a former electronics engineer so he should be able to compare the parts and come up with something if I don't have the time to do it myself.

I bought enough parts (except for MBC's) to build three of these just in case I damage one or want to test it on someone elses car.

 

I wouldn't mind testing it on my car
My plan is for a different management system, however this boost control system should still work. It also may be better than my stock setup until i get my management system in place.

On a separate note but about the CEL, I removed the stock solenoid for the fuel pressure, and put a 33 Ohm resistor in its place, however I still get a CEL even after disconnecting the battery. Do the CEL need to be cleared with a tool, or is the resistor not working?

 

You have to clear the CEL first, it might come back if you just run a resistor though, since it might be measuring more than just the load across the circuit to see if its healthy..

 

Disconnecting the battery for a couple minutes should clear the CEL. Well it always has for me. But if not you local autozone could clear it for free.

Jack - how much was all the parts to do this? I already have a MBC so i would need one of those. This is going to be a nice feature. Now all I need is a UTEC I should have it in next week so just prepare yourself for some questions

Ben

 

In total, it shouldn't cost more than $40 if you already have the MBC.. The only important feature of the MBC you decide to use is that it is a checkball style (like the hallman) and make sure the outlet of the MBC has a small bleed hole.. If it doesnt the actuator may remain pressurised when the solenoid and MBC are closed, if that happens you can either construct the setup without the check valve on the vacuum source line, or drill a small bleed hole (1/32") in one of the fittings or T's on the actuator side.. (preferrably one close to the MBC)

The check valve is there for a reason, under vacuum the system obviously doesn't need to operate and it will help the rest of the vacuum circuit you tapped into retain a normal signal, also, it shortens the length of the hose that the signal has to traverse when the boost system is not in use (part throttle driving and slowing down) and should help idle a little..

You can use any "Grainer valve" type system, which is basically an adjustable spring/ball valve. Don't use the really inexpensive rotary valves or an aquarium valve, although it would work, it'll whistle and you'll get poor boost response.