Quick questions about wastegates and electronic boost controllers
1.Can someone explain how people use a wastegate as a boost controller ?
2.What happens if you have a electronic boost controller and it's off but, vacuum lines and eveything is still connected?
Open to hear everyone's knowledge and response about this topic

 

I have the Greddy Profec-B (the old one) that was on the car when I bought it. I still haven't figured the stupid thing out, but hopefully my tuner can. The way I understand it is if all the settings are set to 0 then it will run off WG spring pressure. From there, you adjust the settings in percent increments to manipulate the rate of speed the WG opens in order to reach the desired level of boost you set it to. But it's weird, you have to really have it dialed in so that you don't have boost spike and so that the boost doesn't peak and then drop off, etc. It's not as simple as saying "I want 20psi and setting it to 20 and bam you have 20psi".

 

Here's a good article on the Greddy. I think a lot of guys just end up using manual boost controllers: https://www.evolutionm.net/forums/ev...b-spec-ii.html

 

I have the same one in my car but I can't figure out if the cars running off wastegate pressure or if I have a boost leak because my evo 8 only hits 1 bar and as you know from factory they run atleast 19psi so that's whats making me think if I have a boost leak or is the boost controller no good...The reason am guessing it's no good is because when I first got the car my guages and BC didn't work a few weeks later I figured how to turn them on. That's when I notice how much boost I was running and I said something isn't right here so I looked up the manual of the BC and figured I have been driving with it off so I got excited think my car was about to feel way better now that the boost controller was going to be on but there's no difference in boost it still hits 1 bar im guessing the boost controller is problay not working no more it's same in HI and LO I feel like either it doesn't work or the connections do look a lil f'ed up so maybe it's problay a connection that isn't hooked up ...And that's what made me wonder could I be running off wastegate since the BC is off or does it run by what ever the car is programmed to run off since the last tune?

 

The boost controller solenoid could be bad. But then again, I thought mine wasn't working right either because I could never get over like 22psi no matter what I did, but as it turns out there were a ton of issues with my car not visible to the naked eye. And when I say 22psi, that was like one time that I got it that high. Most of the time I couldn't get past 14 or so psi. Turns out, turbo mani was cracked, o2 housing was cracked and a host of other things and probably some boost leaks as well. That's why it got a whole new hotside kit and is in the shop.

 

I have tried to get pass 15psi .I try'ed messing with the boost controller to a setup that someone in the link you posted said but from what I was seeing it look like it was still running 15 psi the highest went to 15.9psi..I am going to get a new bc and a few other stuff and a tune in a few weeks but it bothers me that I can't pass 15psi...do you have pics of were it was cracked or hows away I can check it ?

 

No, no pictures.

 

OP: Does your turbo have a stock, factory Mitsu VIII actuator on there?

 

I'll problay wait for my tune day maybe it just could be the boost controller hopefully..

 

Umm from what I think no because I bought the car 5 months ago and it came with a fp green

 

yeah honestly I'm hoping my tuner gets this thing dialed in. Once it's set it's set and I can write the settings down just in case but once he gets it where it needs to be I'm going to leave it alone.

 

So, currently, as it sits, your car has an FP 73 HTA Green on there? Is that right? Or, is it an Old-School Green?

 

First thing for you to do would be to perform a boost leak test. Once that is done and you are sure that the car has no boost leaks, then we can bypass the boost controller/boost solenoid etc., by running the actuator straight from the j-pipe nipple to the port on the actuator to establish actual wastegate spring pressure. Then we can go on to increase WG spring pressure to a higher level.

In the process you will learn how to use the WG as a boost control device as per your 1st question in the opening post.

 

Since your car is not stock by virtue of having been fitted with an aftermarket turbo and quite possibly an aftermarket actuator, and given the possibility that the previous owner may have altered the factory boost/vacuum hose assembly or the boost control solenoid then you can't assume that the turbo is gonna hit stock boost levels. Furthermore, as you yourself mentioned, there may be a boost leak.