B4512 Filtered RPM Airflow Correction - Values??

[SSpdDmon]

The main issue here with my car is stalling. I have a 92mm super ported tb that is not that linear. I need the rpms to come back down slowly in order for it to not stall.

I do not zero out the first cells of the DAC and it idles fine. It will stall on some occasions and it usually is after revving from 3krpm or over. Even on my stock z06 i do notice aome under rpms after revving but since its factory it will recover nicely as a stock car. Given that this tb is huge and a little too close means zero airflow i get this issue!

This happens more often with the a/c.

Next step is to try a stock 90mm

You just ID'd the place you need to fix this. You said "after revving". The first thing that says to me is, adjust the throttle follower. You can do this 2 ways. Increase follower airflow or reduce the decay rates.

Another option would be to slightly increase the throttle cracker some incase it's happening in a situation similar to:

- I was driving down the road at 3K RPM, took my foot off the gas & coasted for 10 seconds down to 2500 RPM, pushed the clutch in and it stalled on me.

Throttle follower is based on throttle movement. It's there to "cushion the blow" of changes made with your right foot.

Throttle cracker is based purely on MPH & RPM. If the car is at "X" MPH and "Y" RPM, the IAC allows "Z" more grams/second of airflow to pass. So, this is like the idle screw on a carb...but only for when the vehicle is in motion above the thresholds I previously mentioned.

[SSpdDmon]

See edit above.

[Highlander]

've had that happen to me from time to time. Coast down, dump clutch and stall. But only with this tb.

I have drop al decay rates to .01 for the most part and i still get the issue, hence why i was looking at other tables. Specially this one that deals with rate of
change.

[SSpdDmon]

One other important thing to remember about B4512 - it works off of a delay. The delay description reads: "... (B4512) is enabled this many seconds after the engine speed drops below the PCM's desired engine speed." On the f-bodies, that delay is usually set between 1 and 2 seconds. So essentially, that means that this table isn't going to work as a stall-saver....assuming the descriptions are accurate.

If you want Highlander, post up a copy of the tune and I'll see if there's something I can do to help.

[Highlander]

SS, I have also noticed, but not verified, that even with the TC activated, it will get into an idle mode if the RPMs get into the range of desired idle. Now, I have disabled TC completely because either you would need too little airflow as the rpms hang a lot and on the next day you would need a lot more airflow or it stalls. Then you have a "rolling idle" that varies from time to time from stalling to 1100-1400rpms... It gets annoying.

I disabled TC and let the idle do it's thing... Now, I have only done this with this car as it has been a REAL pain because of the stalling issue. As of now, it doesn't stall... or at least it hasn't in the past couple of days.

The best results where to adjust b4504-6 to make Filtered RPM airflow come on first and then DAC and LASTLY the learned values. I did this because with the filtered RPM airflow, the way I see it... It will control the rate of deceleration of the engine when you dump the clutch or whatever. Then the DAC will have "different" values if you have the A/C and then the learned values will do it's thing to bring the idle nice down and safely...

THus far this is the combination I have used to make it work.

[SSpdDmon]

SS, I have also noticed, but not verified, that even with the TC activated, it will get into an idle mode if the RPMs get into the range of desired idle. Now, I have disabled TC completely because either you would need too little airflow as the rpms hang a lot and on the next day you would need a lot more airflow or it stalls. Then you have a "rolling idle" that varies from time to time from stalling to 1100-1400rpms... It gets annoying.

I disabled TC and let the idle do it's thing... Now, I have only done this with this car as it has been a REAL pain because of the stalling issue. As of now, it doesn't stall... or at least it hasn't in the past couple of days.

The best results where to adjust b4504-6 to make Filtered RPM airflow come on first and then DAC and LASTLY the learned values. I did this because with the filtered RPM airflow, the way I see it... It will control the rate of deceleration of the engine when you dump the clutch or whatever. Then the DAC will have "different" values if you have the A/C and then the learned values will do it's thing to bring the idle nice down and safely...

THus far this is the combination I have used to make it work.

That's what I get confused on though. If that table works off of a delay as the description indicates, it won't do anything for you until a second or so has passed after the RPM drops below desired.

Either way, I'd be happy to take a look at your tune...and if I get a minute, show you how I would have set it up. Up to you...

[Highlander]

Here it is... Check it out...

[SSpdDmon]

Here it is... Check it out...

Here is a bit different spin. It's the direction I would have taken to set things up.

[Highlander]

The delay is set on: B4503

I am going to send you my last tune, which has thus far worked.

[Highlander]

Undriveable... but I don't blame you... my setup is barely driveable... I will change that throttle body... i am tired of dealing with it.