A/F readout delay

[Marty Buth]

On the racepak, how much delay from the RPM readout is the Air Fuel readout?

[Bob Shaw]

Originally Posted by Marty Buth

On the racepak, how much delay from the RPM readout is the Air Fuel readout?

Marty,
On my Holley system it seems to be .4 second.

[Marty Buth]

Originally Posted by Bob Shaw

Marty,
On my Holley system it seems to be .4 second.

Thanks Bob! I was expecting something like that How did you determine that amount of delay?

[Bob Gullett]

About .2 of a second on the racepak. I look at engine rpm and my shift point vs biggest fluctuation of O2.

[Bob Shaw]

Originally Posted by Bob Gullett

About .2 of a second on the racepak. I look at engine rpm and my shift point vs biggest fluctuation of O2.

My delay is .2 second also. Each step on the graph is .5, not 1.0. I figured wrong.

[Marty Buth]

Thanks Bob Gullett and Bob Shaw! Good information!

[Ed Wright]

Marty, if your car is EFI, make a big change at like 6000 RPM, then see what RPM it shows up on your logger. I mostly look at high gear, since the A/F vs RPM error is going to be greater in lower gears due to the RPM increasing so much faster. And, I assume, if you leave off a 2 step, that your launch A/F looks much leaner due to the misfires caused by the 2step. Misfires put more oxygen in the exhaust, and our Wide Band O2 sensors calculate the air/fuel ratio by oxygen content.
I hope if you already knew all this, I didn't offend you. Maybe somebody did not know. Not trying to be a know-it-all.

[Tom Goldman]

Just looked at my first run here at RT66 , my RacePak O2 is .021 behind RPM

[Marty Buth]

Originally Posted by Ed Wright

Marty, if your car is EFI, make a big change at like 6000 RPM, then see what RPM it shows up on your logger. I mostly look at high gear, since the A/F vs RPM error is going to be greater in lower gears due to the RPM increasing so much faster. And, I assume, if you leave off a 2 step, that your launch A/F looks much leaner due to the misfires caused by the 2step. Misfires put more oxygen in the exhaust, and our Wide Band O2 sensors calculate the air/fuel ratio by oxygen content.
I hope if you already knew all this, I didn't offend you. Maybe somebody did not know. Not trying to be a know-it-all.

All good Ed, definitely not offended. I did know about the 2 step. I hadn't thought about altering fuel counts at a specific RPM to track the delay. That is a good idea. Thanks Ed!

[Marty Buth]

Originally Posted by Tom Goldman

Just looked at my first run here at RT66 , my RacePak O2 is .021 behind RPM

Thanks Tom! Quite interesting what you are seeing. Bob Shaw and Bob Gullett are seeing .2 seconds and you are seeing ,02 seconds. Do you have any logic about why you are seeing so much less delay?