Commanded PE not Working properly

[tbssgto]

Hey guy's i'm tuning a 1998 Buick Regal GS with a Turbo Kit on it and we have made some good progress with it but for some reason I cannot get the Commanded Power Enrichment to work properly. I have it commanded at 11.8 and as soon as the car hits WOT it just peg's 10.0. I have looked over everything I can think of and I can't see anything that's hindering the PE Table. If anyone can take a look at the tune and see if anything looks out of place that would be great! Thanks.

[bilemke]

Ahh.. Just to be sure, you are commanding 11.8 and getting 10.0 on your wideband? I ask, because that scan does not show any AFR reading (commanded or otherwise).

[tbssgto]

Yep the wideband is showing 10.0 on WOT

[E85GP]

When your PCM commands 11.8 AFR, it calculates the amount of airflow coming in thru the MAF, and then determines how much fuel it would need to achieve that AFR. It then uses the injector flow rate table to decide how long to open the injectors to flow that amount of fuel.

It is not a closed-loop system, so the car doesn't read the AFR with the O2 sensor and adjust. It just uses the MAF table and the Injector Flow Rate table.

So if your MAF values at the higher MAF frequencies are too high, it'll make the car think more air is flowing in, giving you more fuel than you really needed.

Thats why the first part of WB tuning is to adjust your MAF table so that in PE Mode your WB measured AFR matches your commanded AFR.

Once you adjust the MAF so that it's got the right air flow values for the upper frequences, then you'll be able to adjust your WOT by adjusting the commanded AFR.

[bilemke]

When your PCM commands 11.8 AFR, it calculates the amount of airflow coming in thru the MAF, and then determines how much fuel it would need to achieve that AFR. It then uses the injector flow rate table to decide how long to open the injectors to flow that amount of fuel.

It is not a closed-loop system, so the car doesn't read the AFR with the O2 sensor and adjust. It just uses the MAF table and the Injector Flow Rate table.

So if your MAF values at the higher MAF frequencies are too high, it'll make the car think more air is flowing in, giving you more fuel than you really needed.

Thats why the first part of WB tuning is to adjust your MAF table so that in PE Mode your WB measured AFR matches your commanded AFR.

Once you adjust the MAF so that it's got the right air flow values for the upper frequences, then you'll be able to adjust your WOT by adjusting the commanded AFR.

Couldnt have said it better...

@tbssgto
Noticed in your bin the first time I looked at it that the upper end of your maf table has been increased by quite a bit. You might be commanding 11.8:1 AFR, but if the MAF table says there is more air going in then there really is, you are going to get way more fuel then needed to hit the target/commanded AFR.

[tbssgto]

Thanks guys, I'll adjust the maf tables and see how that goes!