[Ilma]

Background:

135i basically stock except for DCI and VK intercooler, Procede Rev 2 latest autotune maps.

I have 94 octane available so I have been running UT=37 which shows on my datalogs as 14.5 psi or so.

Normally I set my Ignition correction at IC=50% and this autotunes itself down to 20-30%.

But lately, I noticed that my ignition correction (Debug Byte 2) started to rise back up, so I did a few datalogs to see why and found that my timing advance into 4th gear was taking a huge hit and basically hitting zero degrees of advance.

This happened right after I filled up at one of the PetroCanada stations which have recently taken over Sunoco's 94 pump octane, so it might be related to bad quality octane .

In any case, you can see in the first datalog that my boost peaks around 14.5 psi and my timing at the top of 3rd gear dips and then only rises back up to 8.3 degrees before the shift into 4th.

The timing for the shift into 4th is dismal and you could really feel the car lose steam and momentum with the huge timing drop. Some major knock going on here.


The first datalog is going from 3rd gear to 4th and illustrates the timing problem.

The next datalog (scroll to the right) shows what happened when I lowered my user torque to reduce boost by 1 psi to down to 13.5 psi.

My timing curves look great again......almost like stock!

Nice upward slope hitting 12.5 degrees of advance at 6500 rpm and holding onto the advance very nicely into 4th gear as well. No dips.

So I am getting the impression that since I have stock downpipes and no meth it's really wise to keep my boost levels around 13.5 psi. Especially when octane is in question.

The other possibility is my fuel pump may be acting up as I have recently noted two 2AAF fuel pump plausibility codes........but these were during cold start-up idle rpm only.

So could 1 psi of boost push me over that much into the knock threshold?

I am thinking this is the most probable explanation.....running too much boost for my modifications


Car rips nicely now and is very responsive and eager to pull.