Hey guys,

I don't have the logs with me at the moment, I will have them uploaded around lunch time today, but I believe I have a defective 3-port.

Here is my situation.

1. Switched back to Load based
2. Error correction disabled and verified
3. WGDC set to achieve ~17psi

Boost curve ends up being a sharp sawtooth all the way across. The difference in high to low points of the sawtooth are almost 2psi. The high and low points are roughly (going from memory here) about 500-800 rpm's apart. AWGDC's are set to a smooth ramp up, so this is not WGDC mis-configuration.

3-port is connected with ~24-30" of Vac Line on each port. Could the Vac Lines be to long?

I reduced some of the WGA preload (2 revolutions) and connected the WGA directly to turbo outlet nipple and got a very smooth 11psi across the board, so I don't think it's the WGA, unless excessive WGA preload could cause the sawtooth pattern.

Anyway, most likely I will order another GM 3-port, unless some of you have seen this sawtooth pattern before caused by another issue.

Boost and Error correction:



Boost / AWGDC / EC:

 

would be helpful to see your WGDC maps... did you log activeWGDC correction? what is your correction interval set at?

 

Yes, but Error correction was zero'd out, and the logs prove that. Correction interval is 2

I'll have a log up around 11 CDT today.

 

just clarifying some things first, so when you're connected to the 3port you didn't have any boost or something? if you're building up boost, if you increased the wgdc it didn't increase the boost?

did you check the fittings in your 3port? long hoses will not change/effect the boost that big..usually just small difference..try changing/borrowing the hoses first..it could be a leak somewhere pre/after 3port (depends if you're building up boost or not answer)..

 

I'm pretty sure that its *possible* for too much preload to cause that, but I'm not sure thats the issue.

I think longer lines can actually smooth the pulses from the solenoid a bit... but obviously response suffers slightly. Less response should be more smooth though if pulse frequency is low. This is unlikely to be very noticeable though.

 

Tony, I'm not sure I understand you questions fully.

Increasing WGDC does increase boost overall, however it's still very up and down like a sawtooth pattern. As soon as I post the logs today you'll see.

The ports are connected properly I believe because the boost does rise and fall as I increase/decrease AWGDC.

I haven't tried the 3-port since I lessened the preload on the WGA, maybe I should..

 

ohh my bad.. did quite get that "sawtooth" thing..forget my questions lol

anyways, yea try the 3port with the lessened pre load.. like what fostytou said, it could be to much pre load..keep us posted.

 

OP updated with pics of logs.

 

hmmm, i'll check my logs if i can find any..if not probably on the weekend..can't really remember mine..but try logging now with the lessened pre load and see how it goes..

 

Definitely will give it a try before I buy a new 3-port.

 

also... why only 17 psi? that could be the problem... you're just below the optimal range on the compressor(i.e. where the curve is the most vertical), and the transient characteristics of the 3port may not be quick enough at this point of spool to keep it right on the verge.

I bet you see this behavior disappear at a "real" boost level.

 

Nope. This problem occurs at 21psi as well.

I lowered it while I try to figure out what is going on.

Also don't have the resistor on the 3-port so it should be plenty fast....At least that's my understanding.

 

Maybe the extra voltage (i.e. not having the resistor) has burnt it up.

 

We sometimes add a resistor because we are worried about our ECUs, not the BCS. The BCS was designed to run at full output voltage.

It is possible that the driver circuit in the ECU is acting up though, but I don't think that would cause this problem.

OP... did you happen to try a near factory flash and just change the boost settings? Maybe something else is screwy in your ROM.

 

ok guys,

Here is some more testing data. I think I'm convinced my 3-port is bad...tell me what you think.

Below pic is with Load based boost control, EC on, and WGA preload lessened.



Pic below is with the WGA directly connected to turbo outlet and bypassing all ecu boost control, thus runing off WGA boost pressure only. WGA preload is the same.



You guys think the GM 3 port is bad?