Basic Question - PE Effect / Relationship with VE Table

[Awheeler]

Please consider me a novice, so be nice.

I am attempting to use an AEM feed into the scanner to determine AFR / Lambda ratio errors. Going to then adjust the VE tables to as close to 1.0 Lambda as possible. I have studied and understand the basic need for power enrichment tables but am having trouble understanding how this should be used in relation with the VE table. If I use the AEM and obtain 1.0 Lambda for all cells, doesn't this negate the impact of the PE table? If so, how do you tune the VE to ensure an actual ~0.85 ratio for areas of the table that need additional chamber cooling? Should or can PE be turned off like MAF to dial in VE (I really don't like this idea). May be overthinking this, but very confused as to the interaction of PE and VE on needed AFR.

If I am not making sense, please let me know. Definitely a noob here.

Andy

[Alvin]

You don't tune against 1.0 lambda.. You should be tuning against the commanded eq or lambda. That number will change with PE.

depending on the setup the narrow bands would be more accurate to use after you get it pretty close with the wideband. I'm talking about part throttle/idle etc.

[Awheeler]

Thanks Alvin. A few more details, the PE table is at 1.18. The stoich field is at 14.2 (E10). After disabling the MAF, the VE tables are pretty good with + or - 2%. I am logging the commanded eq and it is also very close to the actual AFR. I want to make sure - I think that the tune is doing what you have stated above while idle or part throttle. I have NOT tried to adjust anything with higher RPM or full throttle. This is where I am a little worried to go further. I do understand that the commanded eq will change once PE begins. Are you saying that the commanded eq should be 1.0 or ~.82 at WOT and I should adjust the PE tables so that the commanded eq is normalized (i.e. increasing the commanded from .82 to 1.0), then calculate the percent of change needed in the VE?

[Awheeler]

Okay, after thinking about it a little more, it clicked - I think. If I adjust the actual AFR to the commanded and the commanded will be stoich and / or adjusted with the PE variable when applicable, the correction factor needed to adjust the VE table will still be accurate. Sound correct? Wow, really hard putting this stuff into a message.

[Alvin]

I do not recommend tuning against AFR. You have the calibration set for 14.2 but the wideband is still setup for 14.7. use lambda or EQ for both and you'll get good results.

[Awheeler]

Completely agree, just didn't articulate it well. One more question, when in speed density only, is power enrichment active?

[5FDP]

Yes.

[Awheeler]

Thanks everyone. Got the ve tables much more in line. And from your advice, this is making much more sense.

Last missing piece... What does everyone use for enrichment ramp in. I.E., commanded eq of 1.0 is good for cruising around and under moderate load. But ~.85 is good for high load, WOT. What type of transition do you use to go from 1.0 to .85?

[5FDP]

I just pick a throttle percent like 80% of the time. I usually have it switch to PE at 65-70% throttle.

The ramp in rate I put at the fastest most of the time.