Running very lean during engine braking, exhaust popping

[grover]

I recently installed ITB's on my '73 BMW 2002 and am continuing to try to refine the tuning. One issue I'm currently having is that during engine braking (while going down hilll in 2nd, for example) I get really lean AFR readings (18-20:1) in addition to a lot of popping from the exhaust. However, when I run datalogs through Tuner Studio, it is not making any recommendations to richen up the mixture in the cells where I see this happening (low MAP, 2-3k rpm.) Any suggestions on how to render this? Thanks in advance.

[grover]

I received a friendly reminder that I neglected to enter some key information on my initial post, apologies for this:
I'm running MSII V3, with code version 2.89100. I am also utilizing EDIS for spark control. I have a "common" collector pipe for vaccum signal connecting to each of the four intake ports. For now I'm running strictly on speed density but plan to move to a split set-up also utilizing AlphaN at higher MAP when I get closer to being dialed in. Please let me know if you need any more specific info to assist with my issues. Thanks. Grover.

[kjones6039]

It would help to see your log I think. It may just be a matter of enriching the low map areas of your ve table and a log would help.

Ken

[grover]

Thanks Ken. Here is a brief datalog I took yesterday as well as an MSQ.

[kjones6039]

If this was my ve table I would certainly increase the value of the cells between 2200 to 3400 rpm and 30 to 45 kPa.

I would select all of those cells in TS and increase them a few percent at a time and see if that helps.

Ken

EDIT: I would also save my ve table prior to any changes so I could go back to original if necessary.

[sammy]

Hi Grover,
I'm following the same path as you - ITB - except on an Alfa Romeo.
my Version of code is 2.86.

I Havnt got to Blended AN yet, and I'm finding similar problems as you with the straight SD.
Poping from the exhuast etc
I'm also getting some flat spots and its going rich r lean when I dont expect it too

how have you got on with your setup?
have you gone to Blended AN/SD yet?
Sam