Ok so I was recently tuned, upgraded BCS to the 3-Port... But I have come to a concerning question... I was under the impression that upgrading to the 3-Port, would require less WGDC to achieve same boost... Well, I know its supposed to require less duty cycle! So my question is why is it I require soo much???

To answer your first question: I bought the 3 port from ac delco, bought a couple 10 ohm, 1 watt resistors w/ heatshrink, but Im not sure how the tuner installed it! And Im not the most mechanically inclined. I need some help tracking this issue down.

The wastegate wasnt touched. Myabe it needs to be adjusted??? Maybe the 3-Port wasnt installed properly I think I can see the solenoid, but cant follow the lines.

Here is a look at my boost tables 26psi.

 

Most 3 port solenoids are able to run in both bleed (Stock) and interrupt configurations. It is possible that the solenoid is in a bleed configuration at which point your WGDC would change very little. I know the Perrin/Grainger 3 port can do both but I am not sure about the GM as I have not installed one since the Grainger solenoid is usually cheaper and a virtual carbon copy of the Perrin.

Check to see if the BCS has a return line to the intake and if the stock hoses at the compressor housing and wastegate were re-used in their factory "T" configuration.

/brox

 

What does your boost vs RPM profile look like? A short table (e.g. 1000 rpm, xxx psi, 1500 rpm, yyy psi, etc) or a graph of boost vs rpm will be good enough.

 

Thanx, I'll check it out...

 

boost graph from evoscan.



breakdown:
@ 3000 13 psi
@3500 26.5 (overshot a bit)
@ 4000 24.5
@4500 24
@5000 23.8
@5500 23
@ 6000 23
@ 6500 22
@7000 21 ish
@ 7500 20 ish

 

77% looks about right to me...

 

Looks about right for 26psi to me too (i use 100 duty on top and bottom thou) ... also i'm not sure what you're comparing it to.. stock bcs is usually run at 100% with pills in vac lines.. If you want less duty, maybe put bigger pre-load on WGA spring...

 

+1

 

As they said, for the boost you're running it looks correct.

I have seen some very wierd WGDC's before under different configurations. I recently tuned a Subaru with a stock BCS and was only at 33% WGDC and overshooting. I finally cut it down to less than 28% and was able to get it to hit 17reliably without overshooting. I even cut his compensation tables by 50%. Even my logs showed no more than a combined 36% WGDC and it was hitting near 21 PSI on his VF-39.

/brox

 

I bet if you switched the 2 vacuum lines that go to the BCS around you would need to use normal (high) WGDC numbers. It really doesn't matter though, i'm sure the BCS goes both ways so to speak just fine ..

 

If you switch the lines around, when the ECU tries to correct, it does it in the wrong direction. I think Al/lupo had that problem when he installed his. It would work that way if you switched the negatives and positives in the TBEC table, but unless you do that the ECU will either clamp you down to wastegate boost or shoot you up to boost cut (randomly of course).

 

^ Good point! I was just trying to say he maybe has them wrong in the first place and that's why he needs to switch them around...

 

I was comparing it to mrfreds example on his "direct boost control" thread on page 2. where hes using 50% and even as low as 42%, and I require a straight linear duty cycle of 77% till 4000. Now that I just thought about it, mrfred uses a bleeder right, could that be the difference? I spoke to a tuner who had recently tuned a car w/ the 3 port, and didnt need that much duty cycle either... Im just trying to understand, and confirm that it was installed properly. I have no1 I can compare w/, so I appreciate the advise guys!

 

If there is a bleeder/pill in one of the lines, then yeah, one would need lower duty to get the same boost.

 

Good to know. I was thinking there was something amiss... Thanx for the input guys.