maxcooper

Can the PFC be used to control an external wastegate (as you would run with a single turbo) with the stock wastegate solenoid?

Read more about this idea on my web site.

Here is how I was thinking of setting it up:

spyfish007

First of all ... change the PFC to non-sequential mode by going to etc->function select->sequential and changing the symbol. This will disable the sequential control system and then boost is controlled via the pre-control solenoid.

I am not sure if you setup will work. I am really thinking about it. I think the following might work and it is basically the stock system and what I am doing in my non-sequential setup.

boost pressure -> bleed valve -> wastegate -> pre-control solenoid -> vent

Make sense?

maxcooper

spyfish007,

Wow, I didn't think I'd get feedback so quickly!

That is good info about using the PC solenoid for non-sequential setups. It sounds like I should use the PC solenoid instead of the WG solenoid in my setup.

My external wastegate (and external wastegates in general, AFAIK) are not like the stock wastegate with two nipples for the same air chamber. Instead, each nipple goes to a different side of the diaphragm. So, normally you route the boost pressure to the lower nipple so that it will open the wastegate with pressure. In fact, you can leave the other nipple open and the wastegate will open when the pressure overcomes the spring.

You can add pressure to the top nipple to hold the wastegate shut for more boost. That is what the setup I am proposing is designed to do. The pressure added will increase with the duty cycle of the solenoid, which is the same relationship as the stock setup.

Thanks for the info, I'll have to change the diagram or make some notes on my web page now...

-Max

spyfish007

Cool .... sounds like a good setup then. I wasn't really sure how an external wastegate worked. I knew it had two nipples but I wasn't sure if is was the same chamber or different chambers, but now I know. Anyway your logic of your setup sounds good to me. I am curious to see what you get. I am getting the Apex kit before too long. I will probably use a Profec to control boost, but you never know.

maxcooper

My initial findings are that this seems to work, but I was getting way too much boost with a #58 Holley carb jet as the orifice. I simply removed the vent line from the 1/4" hose tee that it was connected to (leaving a BIG vent) and it seems to work now. My boost is exactly 1.0 Kg/cm^2 as set in my PowerFC. However, I am not sure if this is simply coincidence or if it is really working, so I'll have to disconnect it or change the boost setting and see how the car responds. I'll post more after testing.

-Max

maxcooper

Also, I have it hooked up with the WG solenoid rather than the PC solenoid. The PowerFC manual says to use the primary boost setting when the Sequential Turbo Control option is turned off (as it should be for single turbo), but I think it still uses the wastegate solenoid to control boost.

-Max

spyfish007

What, PowerFC manual? What's that? ..... anyway, I know the pre-control works, because that is what I am using. I didn't know about the primary boost thing though. I need to play with that. I have been trying to use both ... I can't pull full boost 13+ lbs so I wonder if that is it.

maxcooper

I meant the Commander Manual.

So are you running non-seq, but swapped the connectors for the WG & PC solenoids to control boost? That seems odd. In non-seq, the precontrol goes away, and it could not control boost when both turbos are working anyway. Only the wastegate can control boost when both turbos are online. Please clarify your setup so we can figure this out.

Thanks,
-Max

spyfish007

Ah yes, you have me there. The pre-control solenoid controls the wastegate actuator. I am using a home depot bleed valve. I thought I was using both primary and secondary settings in the PowerFC . .. .... but maybe the secondary is useless? I can't pull all the way to 0.9 bar .... but my bleed valve could have gotten messed up. I just haven't played with it for a while now.

spyfish007

Max, I ran the test today and both primary and secondary boost settings work correctly. I don't have my valve tuned correctly so I am not getting fuel boost. Only the top setting (pre-control) in each boost group does anything, which makes sense because I am using the pre-control solenoid to control the wastegate. Let me know what you are seeing. [I'm growing more jealous of your setup by the day ]

maxcooper

I am using the WG solenoid, and setting the boost level I want in the primary setting, but I am not sure yet if it is coincidence or control that is getting me the boost I want. I suspect that the WG and PC solenoids get the same signal if you turn sequential control off. Otherwise, if you went non-sequential and the PFC was only controlling the PC solenoid you would have no boost control.

I'll be doing some more testing and fiddling (and taking some long overdue pics of the whole car ;-) this weekend. Next Friday is my dyno tuning appointment at XS so I am hoping to have the car sorted out and under control by then.

-Max

spyfish007

The more I play with this the more I think they all work!!! So I think we agree. However with my car being down right now ... see thread in 3rd gen forum ... I can't verify the WG solenoid thing. I am giving some thought to using the Apex boost control kit. I am thinking it might do a really good job.

maxcooper

I think the A'PEXi boost control kit has been discontinued.

-Max

spyfish007

Discountinued ... that would suck. Anyway, no more tuning for me for a little while. I think the motor is popped. It is halfway out and it will be out by Sunday.