VE and resultant AFR

[bink]

Open Loop the AFR is based on the Open Loop EQ Ratio table. My Open Loop EQ Ratio table is stock. If the AFR is correct at this point ( Open Loop) will it be correct when I go Closed Loop ( i.e. is the EQ table referenced for the LTFTs and STFt) ?

Do I need to redo the VE table with Open Loop EQ Ratio table values of 1.00?

I've always thought that AFR should be spot on via the EQ Ratio table before closed loop - i.e. not 1.00 (14.7).

Thanks guys!

Cheers,
joel

[SSpdDmon]

Open Loop the AFR is based on the Open Loop EQ Ratio table. My Open Loop EQ Ratio table is stock. If the AFR is correct at this point ( Open Loop) will it be correct when I go Closed Loop ( i.e. is the EQ table referenced for the LTFTs and STFt) ?

Do I need to redo the VE table with Open Loop EQ Ratio table values of 1.00?

I've always thought that AFR should be spot on via the EQ Ratio table before closed loop - i.e. not 1.00 (14.7).

Thanks guys!

Cheers,
joel

If you are forcing open loop and your commanded_AFR=actual_AFR at each point in your BEN map (values of 1.00), that means your VE table is correct. This is because the open loop table is purely a modifier. It says, "If the VE table is 14.7AFR at any RPM/MAP, I'll take it's number and divide it by my number to get the desired AFR." Remember, you're dealing with open loop, which means there is no feedback from the O2 sensors since they only work at stoich. The PCM is using the VE table and/or the MAF (if it's hooked up) to calculate how much fuel the motor needs and has no clue if the math is correct. Therefore, your LTFTs/STFTs are not involved in the calculations given they are part of the closed loop function.

With that being said, I don't believe it really matters if you have 1.00 in the first half of your open loop table or you do 1.13 across all of the cells. Either way, the values in the open loop table should be returned to stock when you're done tuning the VE (if they're not there already).

[Z16DNA]

joel[/quote]

the values in the open loop table should be returned to stock when you're done tuning the VE (if they're not there already).[/quote]

Does this statement hold true if your tune plan is to run SD without a MAF? Do you need to put back in the original Open Loop EQ table values?

Thank you,
Kevin

[bink]

If you are forcing open loop and your commanded_AFR=actual_AFR at each point in your BEN map (values of 1.00), that means your VE table is correct. This is because the open loop table is purely a modifier. It says, "If the VE table is 14.7AFR at any RPM/MAP, I'll take it's number and divide it by my number to get the desired AFR." Remember, you're dealing with open loop, which means there is no feedback from the O2 sensors since they only work at stoich. The PCM is using the VE table and/or the MAF (if it's hooked up) to calculate how much fuel the motor needs and has no clue if the math is correct. Therefore, your LTFTs/STFTs are not involved in the calculations given they are part of the closed loop function.

With that being said, I don't believe it really matters if you have 1.00 in the first half of your open loop table or you do 1.13 across all of the cells. Either way, the values in the open loop table should be returned to stock when you're done tuning the VE (if they're not there already).
Thanks, again! I'm Open loop through the MAF. Have been for a pretty long time. Mostly my AFR reflects the EQ Ratio Open Loop table. I've not tried SD with the Ben factors. I'm going to try SD - Open Loop soon, for fun and then try Closed Loop through the MAF.
I've seen several posts about tuning the VE table at 13.00 or 14.7 AFR and was told my VE would be off as I tuned it at EQ Ratio ( "off" when I eventually tried closed loop). This didn't make sense to me so I thought I'd ask.
Cheers,
joel

[SSpdDmon]

the values in the open loop table should be returned to stock when you're done tuning the VE (if they're not there already).

Does this statement hold true if your tune plan is to run SD without a MAF? Do you need to put back in the original Open Loop EQ table values?

Thank you,
Kevin

Yes, you should return the table to its stock values. The open loop table is like a safety net if something that is required for closed loop operation fails (i.e. your B1S1 O2 sensor). If you look at the values, the numbers at operating temps & normal driving conditions are pretty close to 1.00 (stoich). As far as I know, the PCM will take the greater of the open loop table, PE table, or any other table that has its hand in the cookie jar (i.e. Cat. Conv. Protection) when it's not in closed loop. Also, I believe this table is used during cold starts since your car is in open loop until the O2's get up to temp. That being said...I chose to return it to stock as others have done. On a side note - I did modify my stock table to change the .95's to 1.00.