Quote:
Originally Posted by philly42
Yeah, running those logs may pin point the problem since the system is pretty much all controlled electronically.
Let me know if it would be helpful to compare stock values. Does your JB4 pull values sent to the turbo solenoids and diverter valves?
Isn't max stock boost 16-17psi?
When the hpa value (119.75) is converted to psi, I get 17.4psi
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I reinstalled my JB4...had to spend an extra hour because I dropped a positap cap under the DME and had to go fishing
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So I'm a little confused here... I reinstalled the JB4 to check stock boost but couldn't get over 11.5psi. I then ran on map 6 targeting 20 psi and only got up to 13.5 psi before popping a boost plausibility code. The JB4 said 13.5 but the freeze data says "Pressure upstream from throttle bank 1 (turbo): 176.00 kPa." That is 25.52 PSI. I've always considered this to be a carly issue issue and just divided by 2 to match up with the JB4 reading when determining when the code went. There is a JB4 log of 12.7 and the Carly code of 12.75 (176 to 25.52/2) so I figured this was when the code actually went. Unless I need to subtract ambient pressure?
JB4 only logs wastegate duty cycle which I'm under the impression refers only to the wastegates though I have read come threads on other sites referring to coding DV using WGDC.
I did not get a code while running stock, but consistently fell under DME boost target and couldnt get over 11.5 PSI. Running Map 6 I didnt get over 13.5 PSI and did throw a code. I was getting up to 15.9 PSI running Velos tune only and threw a code. I was getting 16.1 PSI running Velos and JB4 and threw codes.
So, there is a leak preventing me from building boost, it throws a code when I do manage to go over a certain PSI range, and the only way I notice is if I'm tuned and stacked to build boost quickly enough to throw the code.
Probably the charge pipes? I've read some threads of people's plastic pipes cracking over 17 PSI on other platforms, but M5James has been pushing 20 PSI on stock charge pipes for a while now. I've inspected the pipes several times looking for cracks but haven't found anything. The sandwich design would make me think failure would happen around the seams though and not be visible.
I can get a new set that comes with new DVs for $450 plus tax and shipping, but even if that is the issue then I would likely blow it again. Otherwise I could replace DVs and hope that is the problem but if not then get a new charge pipe fabricated from aluminum. I imagine that fabrication would be very expensive considering the design requiring DVs integrated.
My only big clue so far has been swapping around the DVs:
Stock DV Diaphragms: barely builds boost and feels like limp mode even with JB4 and Velos
GFB DV+ Piston: Holds boost over 16 PSI with JB4 and Velos.