FAST System Off - Idle Stumble and Other Questions

[GNDriven]

I have a Classic SFI system. I recieved a startup program from Cal H.

I am trying to work out a bad off-idle hesitation or stumble if you will. It is serious. I am trying to pull out in traffic and blahh the car stumbles and goes dead half the time. The other half I am emberrased that someone can hear it sputtering.

Cranks and Idles very good.

Here is a log of a hesitation event...

Here is a pic of NO hesitation ...

The bottom grey line is the Injector Duty Cycle. You can clearly see on the NO hesiation log the duty cycle kicks up about 4ms. Is this the AE kicking in?

I am trying to correlate the AE vs TPS rate of change map to the log.
I can see the rate of change on the log, but the TPS is expressed in % and the AE vs TPS graph units are in cts/4ms. I do not know where on the curve do I make the change.

Anyhelp? Thanks

 

[HighPSI]

It depends on how quickly you are mashing the throttle. If you are moving the throttle down slowly, you will be on the left side of the screen. If you are stabing it quickly, you will be on the right side of the screen. If this doesn't fix it, look at your VE table to make sure the values to the right and up of idle aren't too small. Also lok at the left side of the AE vs MAP rate of change. I will be home tonight and look at your tune/logs.

 

[GNDriven]

Thanks Cal,

Yesterday, I turned off the WBO2 correction feature. Sitting in gear with foot on break, I started looking at the VE table and watching the activated cells when I applied the throttle. When I touched the throttle the bubble went up and to the left and ofcourse the engine stumbled. I noticed that I could raise the engine slowly and the WBO2 counts will go max lean 15.9. I could hold the throttle steady on the 79kpa row and at 1300 rpm the WBO2 would stay lean. I am guessing the AE vs TPS graph is not activated at this point for the tps is at steady state. Once the engine is past the 99kpa row the WBO2 rapidly decreases. My idle A/F is 13.2.

So, I started adding fuel increments to the cells directly above my idle cell of 27 in the [79, 900] cell. It finally started to respond good around the 58 mark. I increased the adjacent cells and the car would no longer stumble when throttle was applied off-idle. I logged the stumble post fix and now the WBO2 sensor will still sharply increase to 15.9 when I whip the throttle, but not plateau for multiple data points. The WBO2 will spike lean only.

I do not know what is considered a good tip in WBO2 reading?
I am concerned that I am covering up a deficiency in another graph setting by increasing the VE numbers to big values.
Does anyone else have such drastic step size between idle and tipin (cells located right above idle cells)?

The tables below show the original VE settings and the final VE settings that fixed the stumble

Why does this motor require such a drastic step in VE directly above the idle cells?

Original VE table

New VE cells that fix stumble

Log of NO Stumble
I am riding around in a big parking lot pushing on the throttle. Notice the sharp pike in WBO2s. This is much better than the WBO2 leveling out lean for several steps before decreasing.

Thanks Norb for the help!

 

[GNDriven]

Thanks all for offering to look over my program. ESP, NORB, OTTOJ, and BISON.

Currently the engine is running really good. The off-idle stumble was corrected in the VE table. However, the problem may not be fixed. I have changed the lower VE cells significantly. The car will jump off the line now!!!.

I am still concerned about the large step in my VE numbers directly off idle.

I am ready for our big local cruise IN lasting 1 week in duration. Bring it Mustangs, LS1s, whatever.

Current VE table