Anyone run itto this.....

[98SS2836]

What Table should I be looking in to for the following:
When I suddenly let off the gas or come to a stop fast my rpms will drop below my set idle speed then come back up it really doesn't bother me that bad but its just about the only thing that is wrong with the tune Every thing else is pretty much set except for my timing. With this new gas I don't know how I'm going to approach it

[Tordne]

The first couple of things I check is the Desired airflow table and the Throttle Follower decay rate.

Is this an M6 or A4? If it is an M6 do you find that if you were to press the clutch and coast out of gear that the RPM dips or rises? This could indicate that the Desired Airflow table is either too low or too high.

Start with those couple of things.

[TAQuickness]

As Tordne stated, double check the desired airflow table.

If you are rolling, say 50+ mph and let off the gas and it dips, you need to look at the throttle cracker and TC decay rates

If you are quite near stopped and let off the gas or come to a complete stop and it dips, you need to look into the throttle follower and TF decay rates.

[Tordne]

Oops, my bad. Cracker is right! Sometimes it is a combination of both actually.

[TAQuickness]

yessir. My bird was a shining example of both

[Tordne]

The definitive fix is to put back the stock cam. I have no such issues with mine LOL

[98SS2836]

Thanks guys Ill take it for a ride this morning and really see when it happens

[98SS2836]

Going 50mph step on clutch doesn't dip. sitting there idling rev it up it dips going 20mph it dips

[TAQuickness]

sounds like the low end of the cracker table needs a bit more air, and the follower needs a slower decay rate

[bink]

sounds like the low end of the cracker table needs a bit more air, and the follower needs a slower decay rate


I had a similar problem below the T Cracker threshold...say 2-3 mph. Tried many things including all above which helped some. Still occasionally it would drop or even stall. Activating "Stall Saver" helped but it would throw the occasional 1514 (dread reduced power mode)...I reset MAF and MAP Min RPMs for sanity checks and seemed to cure 1514 (SD 2001 OS).

Then I saw this post/thread LS1Tech by P Mack. I tried it and inactivated "Stall Saver". Works like a charm.



here's how to fix rpms dipping when coming to a stop
I feel stupid that I never tried this before. I had my idle airflow tables pretty much dead on and my ve table was damn close. But still when doing parking lot maneuvering and coming off the gas and putting the clutch in, my rpms would drop. It severely pissed me off that I could watch my rpms sit at 300 rpm and never recover while rolling and my IAC/idle trims just sat there like they didn't care. As soon as I came to a stop the IAC would jump into action, but with any speed at all it wouldn't respond. Seems to me that the idle feedback loop should kick in depending on throttle position, not speed. But enough ranting, here is the solution. You have to trick the car into using the timing to recover from rpm dips instead since the IAC won't do it for you. You can do this by making the timing at rpms below your idle (400, 600, maybe 800) higher than the timing at your idle rpm. This applies to the main and base spark tables.

For example, the stock main spark table has 19, 22, and 27 degrees of advance for 400, 600, and 800 rpm. So when you're rolling at 5 mph and the rpms dip, the lower the rpms get, the lower your timing gets. Change it to 35, 30, 25 and like magic no more dipping. Bonus: you shouldn't even need to change your idle airflow tables if you only change the timing at rpms below your idle speed.

Cliff notes: more timing below idle rpm in main and base spark tables

link -> http://www.ls1tech.com/forums/showthread.php?t=533938


FWIW - in case you guys haven't seen this?

:cheers:
joel

[TAQuickness]

great stuff Joel. I had forgotten about that thread. My idle and transistions are dead nuts 99% of the time, but I think the 1% will be resolved with P Macks info.

[98SS2836]

thanks for the input guys ill try this out. One step closer to better dravability.

[98SS2836]

it still happens not as bad ill trfy messing with the cracker table and decay rate and see if that helps a little more. Maby ill add a little more timing

[NAH]

I had a similar problem below the T Cracker threshold...say 2-3 mph. Tried many things including all above which helped some. Still occasionally it would drop or even stall. Activating "Stall Saver" helped but it would throw the occasional 1514 (dread reduced power mode)...I reset MAF and MAP Min RPMs for sanity checks and seemed to cure 1514 (SD 2001 OS).

Then I saw this post/thread LS1Tech by P Mack. I tried it and inactivated "Stall Saver". Works like a charm.

here's how to fix rpms dipping when coming to a stop
I feel stupid that I never tried this before. I had my idle airflow tables pretty much dead on and my ve table was damn close. But still when doing parking lot maneuvering and coming off the gas and putting the clutch in, my rpms would drop. It severely pissed me off that I could watch my rpms sit at 300 rpm and never recover while rolling and my IAC/idle trims just sat there like they didn't care. As soon as I came to a stop the IAC would jump into action, but with any speed at all it wouldn't respond. Seems to me that the idle feedback loop should kick in depending on throttle position, not speed. But enough ranting, here is the solution. You have to trick the car into using the timing to recover from rpm dips instead since the IAC won't do it for you. You can do this by making the timing at rpms below your idle (400, 600, maybe 800) higher than the timing at your idle rpm. This applies to the main and base spark tables.

For example, the stock main spark table has 19, 22, and 27 degrees of advance for 400, 600, and 800 rpm. So when you're rolling at 5 mph and the rpms dip, the lower the rpms get, the lower your timing gets. Change it to 35, 30, 25 and like magic no more dipping. Bonus: you shouldn't even need to change your idle airflow tables if you only change the timing at rpms below your idle speed.

Cliff notes: more timing below idle rpm in main and base spark tables


link -> http://www.ls1tech.com/forums/showthread.php?t=533938


FWIW - in case you guys haven't seen this?

:cheers:
joel

Should these settings work for a MAF-less supercharged setup?

I have made the changes but it is still a bit cranky. I haven't been on a very long run yet.

NAH

[bink]

Should these settings work for a MAF-less supercharged setup?

I have made the changes but it is still a bit cranky. I haven't been on a very long run yet.

NAH
Sure.
I was mafless when I followed PMack's thread/post. It helps catch a falling idle ...especially with ETC. :D

Cheers,
joel

[NAH]

:mad:
Sure.
I was mafless when I followed PMack's thread/post. It helps catch a falling idle ...especially with ETC. :D

Cheers,
joel

Mine is getting worse, keeps stalling. :mad:

There must be something else, perhaps the larger throttle body is responsible.

Incidently, what tickover rpm did you guys have set?