Shaping the boost curve AKA EBC solenoid tuning
 

I want to start playing with EBC since my MS is set up for it.

I did some tests yesterday, all in 4th gear @ WOT. The goal in both cases was to see where I hit boost cut of 155 kpa (~8.5 psi) as a very easy way (in the absence of a passenger) of seeing how soon I can reach the target boost.


Setup #1: Baseline, no changes to set up

Did not hit boost cut. Boost creep to about 1.5 psi over wastegate pressure after ~5000 rpm. Refer blue line in graph below.


Setup #2: Disconnected wastegate actuator with open downpipe

Hit boost cut at 2000 rpm. Meaning I can make the target boost at 2000 rpm with EBC! Great turbo choice, after all!!


Setup #3: Disconnected wastegate actuator w/ baseline full exhaust

Hit boost cut at 3000 rpm. Meaning that even with EBC, I can't make target boost before 3000 rpm. Refer red line in graph below.

http://img185.imageshack.us/img185/7...stcurveck0.jpg

Since I want to keep my exhaust for now, I want to go with setup #3.


To that end, I installed an MX6 boost solenoid since I had it lying around:

http://img356.imageshack.us/img356/2908/dsc00512dw5.jpg

This is how it works, is this different to the GM valve???:

0% DC:

http://img78.imageshack.us/img78/6851/0percentdcni2.jpg

100% DC:

http://img293.imageshack.us/img293/6...rcentdczv4.jpg


To test the solenoid, I set all the cells in the duty table to 100%, and saw if it boost cut anywhere. No dice. That means it isnt leaking the boost at all as it is supposed to.

Should I just get an ARO/GM valve? Or is there an easy way to tune the solenoid settings (frequency, differential and proportional values) to make it respond?

The most amazing thing is that your full exhaust moved your target a full 1000rpm. :eek5: Is it stock? I see the 2.25" dp - but that was used in the first non signal test.

Did you verify the physical action of the solenoid right? Did you verify the ports with some air pressure? I just went through all this with link and ended up putting an led w/resistor in the ebc circuit so I could verify an actual signal from the ecu.

No its an ebay catback exhaust.

I checked the solenoid as per factory manual. At 0% DC you shouldn't be able to blow through Port 3. At 100%, you should. Is there a better way of testing?

0% you SHOULD be able to blow through, 100% not at all.

Still stunned by the change in spool. That's a real eye-opener.

Hmmm... the DC is getting confusing. Let's talk dc + volts for testing. Make sure it closes when powered.

Then I'd verify the MS ebc signal (This is where the led comes in handy for real time testing.)

I'm not familiar with the MS trigger signal, but what about load. Is it sufficient to manage the +v load on the solenoid? or is it something like a +5v signal?

Damn...that exhaust is a real killer, but it sounds real nice and stealth, eh? We have the same one.

that must be for a GM valve. For this one Port 3 must be OPEN at 100% DC therefore you SHOULD be able to blow through it. That's the only way it can increase boost with increasing DC.

So check the brightness of the LED?

Its not a signal, I believe it grounds the solenoid proportional to the duty cycle specified in the table. In other words, the solenoid is always "hot" i.e. +12 supplied, but not grounded. Much like every other ECU-controlled device on the car.

its more like the speed it flashes...

IIRC im using a 470ohm resistor, maybe 100ohm...i cant remember.

yes, I should have just said trigger

Boost solenoids are on/off and work via pulsing- usually going to ground to complete the circuit. When you speak of 100%DC and 0%DC, it sounds as though there's an in between and there's not. It's either +12v or nothing, ON or OFF. The duty cycle (DC) reference is for the percentage of pulses. IOW at 50% DC it is pulsing at rate that for a given unit of time where it is open half the time and shut half the time. I'm stating all this to make sure we're thinking the same.

So- for your solenoid, it wouldn't care what's constant and what's pulsed on the circuit, as long as one goes to ground and the other to hot. I don't see any reason why your solenoid wouldn't work, unless it's broken.