Having trouble returning to idle

[1987firechicken]

I've read through the idle tuning guide by RinkRat but I have been unable to track down what I need to change to even out my idle when coming down from RPM.

I have adjusted the throttle follower to decay faster, increased the timing on idle underspeed tables, but everything I'm trying doesn't seem to make a dent. When I come down from RPM to idle it will dip into the 300 RPM range and most of the time recover however I'm tearing up batteries when I have to start it 13 times a day.

I think I've got the idle most of the way dialed in but I'm not 100% sure.

I've also run searches but I couldn't find a solid answer on what I need to look at.

Car is LS1 Trans Am M6, stock cubes, TF Heads and the cam is a 236 int 238 exh 113 lsa, MAF is failed out and will not be used going forward.

Attached is the tune I'm running and the last scan I ran, ignore the first part of the scan as I was playing with RTT but at the end of the tune you can see me goose the throttle a bit and the resulting RPM dip.

[HO4THSS]

are you using a wideband? its showing consistant 12.8, but i dont see a wideband in your primary table. i see your stoich afr is set for 14.6, so if you are idleing that rich, try multiplying your primary ve table, column 400 rpm by .7, 800 rpm by .8, and 1200 by .9. then blend all into 2000 rpm with smooth selection and take it for a quick drive to see what it does. i also see that you didnt post the changes to your raf. im relatively new to tuning, but these things helped me get my idle right after my cam install. good luck!

[1987firechicken]

Sorry I forgot to mention that the wideband wasn't plugged in until the end of the log I posted. My AFR is pretty well dialed in at 14.7 with a little flux as expected.

[oakley6575]

You wouldn't want the TF to decay faster. You would want it to decay slower, so it adds airflow longer.

[Chevy406]

Try adding another 15% to your RAF table.

[HO4THSS]

he is using an idle-airflow.cfg that will tell him exactly what he needs in his raf, no need to guess with 15%...

[1987firechicken]

OK just back in from some new tune changes and a new log. I went back and revisited my RAF table to be sure and also to decrease the throttle follower decay. It seems to have helped a little bit but I'm still having issues as seen on the back half of the log.

I was wondering if my high MAP low RPM VE fueling is needing some work. I noticed that my AFR error in that section says it needs more fuel but I'm not sure since I didn't log those cells a whole lot.

Feel like I'm getting closer to the answer but I'm still a ways off.

[1987firechicken]

OK so I started over again and I think it's my throttle follower killing me. Came to that by taking the car out for a VE log and noticed when I'm moving the throttle cracker saves my stall but gives me RPM when I don't want them, since I can dial that in later I'm not concerned with it. However I notice when I'm not moving and rev the engine it likes to die.

Am I correct in this assumption or just nuts?

Only thing that is giving me doubts is I've already multiplied the decay value by .5 and I'm not seeing any improvement. It should be decaying very slowly now so I'm a little confused.

Again any help is greatly appreciated as I called a local tuner and he wants to do an all or nothing tune and will not show my any tips. I can afford an hour of sit down time with him (he is not willing to do this) but not the 400 he wants to tune the whole thing and I learn nothing.

[Zo6 4 Me]

I added to my RAFas Chevy406 said to do and it fixed most of my idle hunting issue.

[WS6FirebirdTA00]

Your TPS is reading 1%. Your idle airflow in the first log is actually indicating you have too much airflow. The added idle airflow you added is only a bandaid on the real issue. Why no MAF?

I think your real issue is your idle timing tables need to be fixed and you need better over and underspeed spark correction. Your idle speed is too low for that cam. If you force it low you are going to make issue, I am not a fan of forcing a car to idle over properly tuning it so it can idle where it should.

[1987firechicken]

Your TPS is reading 1%. Your idle airflow in the first log is actually indicating you have too much airflow. The added idle airflow you added is only a bandaid on the real issue. Why no MAF?

I think your real issue is your idle timing tables need to be fixed and you need better over and underspeed spark correction. Your idle speed is too low for that cam. If you force it low you are going to make issue, I am not a fan of forcing a car to idle over properly tuning it so it can idle where it should.

I was wondering about the TPS reading that way, I was not touching the throttle at all and it was reading that way, I'll try a reset on it.

I need to revisit the Idle airflow table again since I've made changes to a couple other tables. As far as the MAF I plan on running SD 100% of the time and go supercharged later so I figure I should start out to give me more learning time for when I finally go that route, but mostly it's preference.

Any suggestions on the timing and RPM I need to be running on it? There was no general guide and when I force it to a set degree of timing it goes hunting. I only chose that RPM since it seemed to like it but I'll be the first one to tell you that this is all new to me.

I'm used to just tweaking the VE tables not idle tuning so this is all good info to me. Thanks for taking the time to look I was starting to loose hope here that I'd ever get it right and have to drop $400 on this thing.

[WS6FirebirdTA00]

You want enough timing to idle well, but you also don't want it too high to where you don't get any engine recovery at lower speeds/engine torque. I know that is pretty vague but I would make the over and under speed spark more aggressive to start with and then leave that alone for a while and go up and down on timing, you will probably end up lower though. I would start with the idle around 900-950 or so. I have a light clutch in mine with a relatively similar cam and have it idling at 1150 or so. Granted, the light clutch is giving it most of the idle issues there, but even without the clutch I would probably like it to be around 1000.