13b street port, bw s475, dual tial 44mm, etc etc. Ive got a greedy profec spec 2 boost controller. It will hold a solid 8-8.5lbs through redline with just spring pressure. I had it holding 12lbs perfect through redline. Im in the process of tuning it so turned it up a bit and it will hit 14lbs then drop to wastegate pressure, then repeat very quickly. Ive played with the gain settings and no matter what it will just flutter now. So I decided to start over. Turned off controller and it holds spring pressure perfect. Turn on with just 5% gain and nothing else changed and it hits 12lbs and then drops and repeats. Ive played with it and no matter what the settings are it will do the same, up and down boost. You can make it hit 16lbs so it is holding the gates. Vacuum lines all good. Motor has been boost leak checked. It is a random issue that started out of the blue. Thoughts? Advice? Im ready to sell the spec 2 and get a turbosmart boost 2.

 

What's your SET value? The GAIN value is not what set the desired boost.

I followed these settings when I was setting up my PRofec B Spec-II, was able to use some of the value as base, then tweak it a little to get solid 12psi and 14psi on my twins.

https://www.rx7club.com/3rd-generati...2/#post7614424

 

Set is 0% the last time i tried. Ive tried several different scenarios. Whats weird is it would hold before. The fluctuation issue started out of the blue.

 

0% SET mean wastegate pressure, I'm at 39% for 12psi and 50% for 14psi.

 

Yea i know what the differtent set, set gain and gain settings do. The issue is no matter what the combo is it doesn't hold. You can raise intial pressure but it still fluctuates up and down.

 

How you have everything hook up? And did you buy it new or used?

 

Its hooked up correct as it worked perfect just last week. And i bought it new quite a few years ago. Im almost wondering if its my solenoid acting up.

 

Yeah, very well could be your solenoid.

 

What do you have WARNING and LIMITER set to?
If the WARNING value is exceeded, gain is reduced the the LIMITER setting.
I have mine set to 0% so if I hit LIMITER, boost returns to wastegate pressure.
This if for a Profec B Spec 2.

 

Warning is set to 180(18psi) and limiter is 0% which according to the manual should be off?

 

Make sure its set to psi and not kPa. 180 kPa is 12.4 psi and would be right were you're having issues.

 

Yea I checked that as well. I ordered a mac solenoid and will try that next.

 

Yeah test your solenoid, the solenoid on my profec B Spec 1 just went out, and i went with a turbosmart eboost 2

 

Tried a new mac solenoid and same exact symptoms. Im leaning towards the profec 2 unit as that's all I see it could be at this point. Im looking at the eboost 2 or evc6.

 

What exactly are your settings right now? and per your previous post you did set units to psi

SET=?
GAIN=?
SET GAIN=?

maybe SET GAIN is too high.

 

Set=5%
gain=5-15%
Set Gain=125

Also when i replaced the solenoid it dropped the wastagate pressure down to 7lbs which is where it was before i installed my wastegate dumps. The dumps are very free flowing. While playing with the gain i tried 5%,10%, 15%. No change. It hits 12.5-13.1lbs according to profec and does the flutter bs, spike, drop to gate pressure, repeat quickly.

 

I don't understand why your SET GAIN is so high. How did you arrive at that number? Remember that the SET GAIN is the pressure at which wastegate is allowed to open--when the control strategy switches from an open loop, fixed ~100% duty cycle based on pressure control to the baseline specified value used in the closed loop portion. SET GAIN or whatever a particular external boost controller calls the wastegate opening pressure setting must be significantly below the level of boost you intend to run.

I have written extensively on aftermarket external electronic boost controllers and how they work. I've posted an overall strategy for tuning EBC's that basically works on any EBC anywhere, whether it's an external box, a programmable stock ECU, or a standalone ECU. The Turbosmart and the Greddy Spec 2 are pretty much the same thing, they just have different names for the same type of settings.

Did you see my thread? https://www.rx7club.com/3rd-generati...-chart-952767/ As I write this, it's at almost 34,000 views and it's linked in the 3rd gen FAQ. There was also a similar thread in the 2nd gen section. I realize that tuning a boost controller is not always the most intuitive thing, but there's a basic philosophy behind it. I'm here to answer questions and clarify points. If you or anyone else getting into it doesn't immediately 100% grasp what's going on that's normal.

Make sure you read posts #1, #2, and #22 several times. #22 is specifically about the SPEC 2 as a lot of people find it to be a very confusing due to some poor choices Greddy made in the name and description of the settings on the box. Yet the SPEC 2, as I illustrate in my chart, is really no different than its competitors.

This image is in post #22. I know there's a lot going on here, but read the thread and it will make more sense.



As for what you should specifically do from here with your car:

1) as I said, read those posts in my thread several times. Think about them. Write down questions you have and post them here. I run a tuning group. I'm here to help people.

2) From my understanding, your units are in psi, so the controller is holding the wastegate shut until it sees 12.5psi. That means actual solenoid duty is 100% until it reaches 12.5psi. Then it will drop to your SET value, which is 5% duty. This is a prescription for oscillating controller, as it is jumping in and out of open loop 100% duty and closed loop 5% duty mode.

You need to see what happens when you reduce SET GAIN. Reduce SET GAIN to about half of what you have and it's likely to calm down.

3) Read the "adjusting your boost controller" section in post #2 of my thread. Read it several times and follow the procedure there. Ask questions if you don't understand the reasoning behind the procedure.

 

Finally had a chance to take it out. The set gain was the issue. I started from stratch and have it holding a solid 15lbs now. Working on the tune. Thanks for the detailed response. Was very informative as usual!

 

glad to hear it! congrats on making progress

 

Didn't want to start a new thread. Having weird issues now. Did a pull other day and then next pull boost spiked. Checked out all lines and they were good. It will hold spring pressure at 8lbs fine but even with boost controller at all minimum settings its wanting to spike to 20+lbs. is it a faulty unit at this point? Tried both my solenoids same result.

 

Nobody's had one malfunction? Greddy tech support must not know either as no reply to two emails.

 

do you have a datalog of the problem?

 

No i was tuning af when it happened. Its holding spring pressure no issue without fluctuations, atleast not that the visible eye could pick up. And then turn ebc on and it just spikes, even wilh all settings at zero or minimum values.