Fluctuating WG pressure
 

Attached are two logs. The first is an older log, one of my first, with the stock injectors and a rough tune. It is a fifth gear pull.

The second is from the other day, new 600's, pretty new tune, autotune only. I have since retuned for 12.0>11.5 at redline.

The question that I have is around 5500, the WG pressures really start to oscillate more and more. Is this just a function of the internal WG? Excessive backpressure? I have a 2 1/2" exhaust but a crappy Flowmaster muffler that was on the midpipe when I bought it.

i tried switching to a tiny vac hose and it got worse than with the old hose and a filter. We're fucked.

where's your MAP line being sourced?

Tee'd off of brake booster line.

Thoughts anyone?

Mine is T'ed off the FPR, try that.

Mine off near/from the IM. The wastegate actuator is sourced from the compressor housing, I run no MBC or EBC:

I tee'd off the small IM nipple below the brake booster line. Mine does something similar but not to the same extent. Will a line restrictor help? I've also got the 18.4 afr spike that I haven't been able to tune out.

Its most likely back pressure man but its not bad enough to where you should need to worry about it.

Go get urself one of those "universal" T fittings... don't cut it for the part going to your ecu so itll be a real tiny hole. That acts as a good enough restrictor to get you down to +- 3 kpa bounces if that.

I just glued a pop rivet into the 1/4" reducer. Going to try it now. Might even help that lean spike???

Well, no joy on the pop rivet restrictor. It's possible the .060" hole was still too big. I can try smaller. Doesn't cost anything. Didn't notice any difference in how fast kPa's change either when you are on and off the throttle.

Magna mentioned backpressure. That is distinctly possible. I'm running 2 1/2" but it has a Flowmaster on it which I understand restricts flow. It came on the midpipe, so I thought I would try it. I'm planning on a Magnaflow soon.

To put things into perspective:

1) Stock CAT and shit exhaust, 7psi WG, EBC, load dyno
2) 3" Enthuza w/CAT, 14psi WG, no MBC/EBC, street

Conclusion: better spool (some 700rpm), flatter curve, less dropoff.

Damn, check the MAT increase on the dyno run. Back pressure is bad!

Yeah, can't wait to get the big honkin' Magnaflow. It's on order. The rest of the exhaust is 2 1/2" with FM stainlss Midpipe and FM high flow cat so should meet my needs.