Commanded Fuel when in open loop and PE modifier based on RPM

[Thumper]

Hi again
I have another noob question. I am finally getting cracking on with my autoVE. I have been set back by one duff sensor after another. I have intalled the new one and its now doing what it says on the tin....so to speak.

One thing that I need clearing up tho, is the PE modifier based on RPM and the OL commanded table.
How does the PE modifier affect the fuelling and why do you set it at 14.63 during the AutoVE process?
Does this mean that I should see 14.63 on my WB when PE mode is activated or should I see 12.95 as per the autoVE setting in the commanded OL table?

Hope you guys can help novice out here.

BTW, after reading all your posts on idle tuning, I have now waxed the idle. I even got the idle so smooth you cant hear the cam. I was a bit dissapointed so I tweaked around and got it sounding a bit meaner and still keeping a solid idle. This is addictive!!

Thanks for your help!!

[joecar]

Thumper,

During AutoVE you don't want transitions to/from PE to give you incorrect BEN values...
for example, if CFOL was 13.80 and PE was 12.80, when the transition CFOL->PE occurs, your commanded AFR jumps richer by 1.00, and the wideband being located about 24" from the combustion chamber would lag behind... your measured AFR would produce an incorrect BEN during that transition.

The PCM selects the richer of PE or CFOL... so you will see 12.95.

Cheers
Joe

[Thumper]

thanks Joecar, clears that up for me. Really enjoying the software now. The more I get a grasp on it, the more I enjoy it!!

[Redline Motorsports]

Don't forget that once you are done tuning the VE table and start to do PE, that you return the PE values back to "power enriched" air fuel ratio values. You should shoot for 12.7 in PE. Adjust your MAF to dial that in.

Howard

[SSpdDmon]

Another option - if you're planning on returning the car to closed loop operation - is to set it up to reflect how the car will be when you're done. In other words, above 130~150*F, I set the entire Comm. Fuel in OL table to stoich (14.63), adjust my PE enable settings to my liking (based on observed logs - kPa, RPM, TP%, etc.), and set my PE AFR's appropriate for tuning. While tuning, you can use the filters in your log to tune out PE, non-PE operation and the transition between the two (if AFR is less than x.xx, is greater than x.xx, or is changing more than x.xx per 500ms).

Personally, I like to tune based on how the end result will operate. Neither way is more right/wrong than the other though.

[hquick]

I thought I'd heard that people were leaving the PE enabled for AutoVE'ing?
Especially those FI'd???

[Redline Motorsports]

I thought I'd heard that people were leaving the PE enabled for AutoVE'ing?
Especially those FI'd???

Yeah but if command 12.0 in PE and hit PE conditions while trying to dial in cruise AFR of 14.7 you will dilute the readings. By locking out all PE you will ensure you will always be commanding stoich. This is why other adder tables are also zeroed out.

[SSpdDmon]

Yeah but if command 12.0 in PE and hit PE conditions while trying to dial in cruise AFR of 14.7 you will dilute the readings. By locking out all PE you will ensure you will always be commanding stoich. This is why other adder tables are also zeroed out.

Why would you want a 14.7:1 AFR anywhere where PE would normally be enabled? Those diluted readings you speak of should be filtered out IMO - not eliminated because you disable PE.

[BlackGMC]

I am confused, during the AutoVE process your logging the error inbetween commanded and actual... What does it matter if your in PE anyways??? Your still logging the difference between commanded and actual right?

[hquick]

I am confused, during the AutoVE process your logging the error inbetween commanded and actual... What does it matter if your in PE anyways??? Your still logging the difference between commanded and actual right?

That was my way of thinking....but maybe I'm wrong.