So here's the deal, this is a 2008 MR 69k, 2010 Trans (SST), factory replacement, with a Cobb SF intake and Stage 1+sf tune (OTS) for 9 months (v1.08). The car had been driving amazing, not even the slightest issue what so ever. A few weeks ago, I'm in Denver, the weather really cooled off for the winter, temps are ranging from 50-25F, and i have an issue either with the tune or the trans.

The car is un-loading in gear under WOT. What i mean from this that the diverter valve or waste gate is really touchy, the car seems like its not holding boost and almost is lurching between 3-5.5k. I get alot of flutter under WOT

I don't think its an over boost issue simply because the car hits target boost at 5k @ 23psi in 4th gear and Ive never gotten an overboost code. I have however, noticed upon data monitoring via the AP that the Knock readings spiked to 22 on a certain instance in 4th gear doing a pull to log, and the car did the same thing, car was at normal temp just FYI, not a cold engine. After that the car seems to hold around 1 knock count in all other conditions and gears.

Has anyone had an issue similar to this or have any clue what might be wrong?

I'm thinking the following based on condition, but would love some feedback:

1. Wastgate Spring is not tight enough
2. Need new diverter valve
3. Cluches in SST slipping?? (long shot since all other conditions the car is solid)
4. Spark Plugs fouled
5. Bad OTS tune, need a pro-tune


Let me know what you guys think. Ive talked to Chris at COBB in Plano, TX, old stomping grounds, where all the work was preformed, and he thinks it could be bad gas or the plugs, but this has been going on whether the car is filled up at the grocery store gas station or the Shell Station, so i've ruled out bad gas. Altitude is at 6,000ft where I live do you think that could be the issue for a generic OTS map?

Mods:
COBB AP Stage 1+SF
COBB SF Intake

Thanks,
Brett

 

Flashed back to stock, waiting on a Pro-Tune from Tobz here in Denver. Problem is the lower atmospheric pressure here as compared to Texas, car is running Mi-VEC to aggressive on the top end, knock is pulling power and hence the problem!


Stock is quite the step backwards I must say! Cant wait to get the turboback in the mail and pro-tune this B!