Auto VE Idle Commanded AFR?

[CGTMS]

All;

We are tuning a 04 GTO LS1 with a larger cam installed. I setup the Auto VE file and loaded into the car. I noticed that the idle is between 65 and 70 KPA...Seems high (low vacuum?), so we verified the sensor and checked for vacuum leaks. So far nothing has been found.

I also noticed that the commanded AFR sitting at idle (800 RPM) is jumping between 12.9 and 14.64 AFR. It seems as if when the MAP sensor is reading 68 KPA or higher, the commanded AFR is going to 12.9 and when it is less then 68 KPA it is reading 14.64. I check my close loop AFR table and it is set to 14.64

SO I have two questions....

1. Is there a setting somewhere for minimum vacuum at idle that would be changing my commanded afr? Where is the 12.9 coming from?????

2. Even for a larger cam (I don't have the specs currently), does 65 to 70 KPA seem too low? Should I be looking for vacuum leaks somewhere?

Thanks!

[Chalky]

If you are in OL and Auto VE is properly setup, AFR is being read from CFOL table.

Regarding idle KPA, cam size/lsa will have a bearing on vacuum at idle. I run a 224/228 on a114 and see 42 kpa @ 850-875 idle.

[Chalky]

If you are in OL and Auto VE is properly setup, AFR is being read from CFOL table, B3605.

Regarding idle KPA, cam size/lsa will have a bearing on vacuum at idle. I run a 224/228 on a114 and see 42 kpa @ 850-875 idle.

[CGTMS]

Thanks....I think I see what happened. In B3605, "Commanded Fuel When in Open Loop", I set AFR to 12.95 at 70 KPA and above for a ECT of 40 and above. The idle vacuum is so low that it is reading above 70 at times, thus setting the AFR to 12.95......

:thankyou2:

[SSpdDmon]

If you are in OL and Auto VE is properly setup, AFR is being read from CFOL table, B3605.

Regarding idle KPA, cam size/lsa will have a bearing on vacuum at idle. I run a 224/228 on a114 and see 42 kpa @ 850-875 idle.
Heard ya the first time. ;) j/k


Thanks....I think I see what happened. In B3605, "Commanded Fuel When in Open Loop", I set AFR to 12.95 at 70 KPA and above for a ECT of 40 and above. The idle vacuum is so low that it is reading above 70 at times, thus setting the AFR to 12.95......

:thankyou2:

When doing autove, set the Comm. Fuel to stoich for all kPa's around operating temps (greater than 150*F). Just make sure you leave PE ENABLED. That's how you simulate closed loop. If you're concerned PE isn't kicking on soon enough, change the PE Enable table (throttle percentage based).