Timing Map Help / Input - 2009 XB9

[s0dhi]

@lawdog

Great info. I've reverted back to factory timing and you're right, the cost of further tuning timing on a dyno may not be worth it for minimal results.

When you used the wideband for tuning, did you do both cylinders simultaneously or swap a single sensor back and forth? On that note, are the front and rear cyclinders significantly different in their requirements? I see a lot of older threads mention copying the rear map to the front and bumping up the fuelling, but this assumes that both cylinders need the same (similar) fuel at the same load and rpm. Seems counter intuitive to me.

[theMelvster6]

On the timing: it's general consensus that to tune timing properly it really needs dyno time as lawdog stated. Most people just leave it alone and tune the fuel maps.

On the fuel maps: there are many theories on how to tune rear vs front cylinders. Some folks tune the rear cylinder and then copy the map to the front and add 2 across the map. The best way in my opinion is start with a stable map and tune each cylinder separately with a wideband o2. A few Datalog runs and you will have a pretty danm good map.

[s0dhi]

What does it take to get a bung put in the front cylinder? Do folks put in 2 bungs by the collector? Is it better just to get a new header rather than mod the XB9 one?

[lawdog]

Test fit an o2 sensor on the front header where it fits the best. Mark the spot, remove the headers, have a welder weld a bung on, coat the headers, and mount back on.

Turn off closed loop, set AFR to 100, adjust maps to compensate for whatever AFR your currently running.

Mount wideband in one header, plug the other, tune a cyl and make equal proportional adjustments to the other cyl. Swap o2 and tune other cyl. Then go back and do a final check on each one cyl one more time. When tuning you will get to the point you are chasing weather conditions with very small corrections.

Make sure your closed loop areas are 14.7 AFR and turn closed loop back on or run open loop with AFR of your choice.

[theMelvster6]

Stainless Bungs can be found easy. When I get mine back together I'm going to weld two bungs (one in each primary) right above the collector for easy access. It's really pretty easy job if you have a welder buddy or you can weld yourself. I believe the xb headers are 304 stainless.

[s0dhi]

@lawdog and @theMelvster6 thanks for your input.

Sounds like a project for next winter. Having said that, do you think there is value doing some narrow band tuning right now?

[theMelvster6]

with a narrowband o2, you can only tune closed loop effectively since it is trying to target 14.7 afr. A narrowband is basically a switch...either too lean or too rich, it can only target 14.7.