Long story short I got a GM Mac solenoid from a buddy, pwm components installed on my p28, the solenoid clicks, 5lb spring in my wastegate, but every time I do a pull I hit boost cut which is set at 10psi for safety measures since I'm working on the tune.

This is how I have it hooked up.


Since I have an external wastegate I have boost signal from the compressor housing tee'd with the bottom of the wastegate and the left side port when looking at this picture.
Neptune settings look like this:

Disregard the frequency, I have it set at 31hz.

I've also tried unchecking the invert box, setting the duty cycle to 5 as well. 0 and 100 will stop the clicking. I've jumped and tested the pwm switch it clicks. I've tested the solenoid with air blowing into the left side port to see what happens when i apply 12 volts. Thought I figured it out but still hitting 10psi. If I remove the left side port connection and plug the line I can do wastegate pressure, but 5psi on a 9:1 gsr and low cam only is slooooowwwwww... What am I doing wrong?

 

Maybe raise your 10psi boost cut limit? If you have it set to 10, you're hitting 10, right?

 

I figure with a 5psi spring, setting the hold at duty cycle to 95 or 5 should only raise it a few psi. I had a 2psi spring in there before this and I was still hitting boost cut with 95 or 5% duty cycle. Debating on if I want to go and get a different mac solenoid.

 

Ok so.. To clarify what exactly you're asking..
Are you wanting to go higher than 10psi?

 

 

Excuse the paint picture, I'm at work so no pics.

The solenoid right now is a GM solenoid and this is how I have it hooked up.

I tuned it at 18psi on crome before switching it over to Neptune RTP, wanted to get PWM working before I tune it again, but its been kicking my butt. If you're curious up to 10psi before I cut afrs are in the 11s.

I'll zero out the hold at duty cycle. So ideally I just have to set the low and high duty cycle to find out my boost for duty cycle then...

Let me know what you think of my plumbing.

 

 

Never ran a GM solenoid but on my mac anywhere from 60-75% Duty cycle will give me infinite amounts of boost depending on the frequency im using.
I use Manifold as vacuum source not the turbo its more accurate as far as what your engine is actually getting. It will be 1-2 PSI higher at turbo portion due to boost drop through piping/intercooler

Read this to get some ideas but It does not give specs for the GM solenoid....maybe teh SAAB would be the GM solenoid? not sure - - Boost solenoids
I usually enable BBG and do like 50%2nd 55%3rd 60%4th 65% 5th. Make a run take notes and then do it all over again till I figure out what Duty Cycle = Equals what boost


Heres the notes from last time I went to the dyno on a 5psi spring using 20HZ Frequency

25% = 8psi
50% = 14psi

I recently changed my spring to 9 PSI and upped my frequency to 50hz and 50% DC is giving me 12 PSI at the moment still taking notes to increase my numbers gradually, but frequency changes things a bit

 

your plumbing like this correct?

 

Yes, I used that picture as a reference.

Did some testing. Normally open because I can blow thru the solenoid when no voltage is applied. The frequency have set settings, I cant put in my own frequency and 31mhz is the highest.

At 0% duty cycle all air is blocked, meaning wastegate pressure, at 100% all air is going thru, meaning max boost.Correct me if I'm wrong.


So lets say port 1 is the entry port, boost pressure is tee'd with bottom side of the external wastegate and goes into port 1, solenoid is set to normally open and flows to port 2 which is closed because of 0 percent duty cycle, but feeds to the top of the external wastegate, I should see wastegate pressure correct?

So we pretend duty cycle is at 100 now, air is flowing straight from port 1 to port 2 because its totally open which in turn pushes the wastegate shut from the top increasing boost. Am I getting this correct?

In this case if the solenoid is clicking and reacting to changes when I change the set duty cycle (because this is how you find what boost level is at what duty cycle), it should be working unless something is physically malfunctioning.

Had a buddy co pilot yesterday. PWM settings do fluctuate when duty cycle is met but we're still hitting boost cut.Tried 0 and 100 yesterday.

 

I ordered a mac solenoid, will update with results when tested.

 

Sorry about the delay, it has been raining and I had to finish the bath remodel.

Found the problem today. I had the 12v power source hooked up to my ground side switch for my gauges and the solenoid worked while the gauges were off, but once I turned the car on and turned the gauges on the solenoid stopped functioning.

Lesson here is run an independent power 12v source Haha.

 

Glad you found the problem sticking with the gm or MAC?

 

I already have the mac wired in and mounted, no point in switching back.