WB or NB for tuning maf

[morepowerjoe]

Hey guys I've been trying to tune my maf and have come to a question. Is it better to go by the Wide Band or Narrow Band for tuning the maf. Obviously the WB can read higher in the rpm but I just did a wb tune with the dfco turned off and my o2's disabled and am getting what seems like a normal reading from the wb and an overly rich reading with everything turned back on the nb. Also my stft are pulling fueling I believe. So am I doing this correctly and should I go by the wb or nb?

Thanks

new tune with new maf and airflow.hpt
newest log.hpl

[GHuggins]

Contrary to what most on here will tell you - it depends on whether or not your exhaust has been changed.

If it's been changed - i.e different manifolds or headers or whatever that changes the O2 location then you need to change your O2 settings to best get the two reading the same. Once they are reading close, you can use fuel trims to adjust closed loop fueling and wideband for open loop fueling and then blend the two portions.

If it's a stock system - i.e original manifolds and O2 locations with fairly new O2's - lower timing, raise PE settings to stay in closed loop a little longer and then you can use fuel trims to get the whole curve close. Believe it or not once a wideband is installed to verify it, this will actually get open loop fueling very close, so something good until a wideband can be installed. The car manufacturers put a lot of time into get the O2 settings right, so they work really good even in the higher rpms for trim data on stock exhaust systems, but keep in mind cams or anything that changes flow through the engine itself will change it slightly.

Something a lot of people out there don't know is that widebands themselves are usually skewed by their manufacturers to favor towards showing a .1 leaner fueling. It's not much I know, but nevertheless a small cushion provided by their manufacturers. For instance I know AEM does this as verified with their company when I was comparing my lambda pro to one...

So basically if your wideband is known good - not reading wrong - use it to get closed loop fueling close and for your open loop fueling. Use trims after that to tune in closed loop solely and then blend the two portions.

[morepowerjoe]

Thank you so much your explanation fits right along. I was kinda wondering about blending the two. Thanks again.

[bfg4wd]

Greg,

You packed so much useful information in this response thank you, I am beginning to understand past mistakes.

With E38 gen4 I added headers which moved the location of the sensor, where do you recommend adjusting for this?

Would this be the ECM 12480 Closed Loop proportional base vs airflow mode?

[GHuggins]

Usually increase integrator delay airflow 1.2 and decrease proportional limit to 1 or 1.25. You can go lower on limit but fueling is going to be slower responding to big trim corrections.

If you want to get real technical about it you can use reported airflow differences and lean more that way for all tables.

If you don't have integrator delay then just play with proportional andproportional limit to get it as good as you can