hello, so I'm new to tuning. I have purchased the tuning school GM Basics and am attempting to tune my car.
The vehicle is a 2004 Cadillac CTS V with an LS6. Engine mods are PRC 2.5 LS6 heads, TSP 228R .600/.600 cam, Kooks long tubes, MSD atomic intake and 90mm LS2 throttle body.
So i changed the throttle body up as in the Tuning Schools instructions. When doing so the car starts right up and idles. On my first log i could see the spark ranging from 15-25 degrees trying to hold the idle. So i moved the Base Line Airflow table up. I then moved the timing to 18 degrees at idle. The car idles just fine. When i come to a stop light the engine stalls. Sometimes the adaptive idle catches it before it stalls and corrects it. I did a log of a stall while parked and a light rev was made. I noticed that the timing was pulled as low as 3 degrees just before the engine stalled. I'm assuming that the computer is trying to pull timing to be able to reduce RPM. But I'm new to this and cant seem to figure it out. Can anyone provide me with any info or guidance? Below is a scan of the engine idling and then stalling after a rev. you can see on the first rev the adaptive idle saved the stall. But on the second one it didn't.
You should also post up a tune. I can see that your long term fuel trims are adding a bit of fuel. After you do all those changes to the engine it takes some work to get everything all dialed in. You should log all of the different things that have to do with idle air stuff. You will want to get your braf tables down first, along with the correct fueling at idle. Then you should log throttle cracker and throttle follower. Could see how your adaptive idle is set up and your idle spark correction. If your braf is set up right and you give it gas at a idle and the rpms go up then down too far until it dies it would most likely be your throttle follower. You would either need to add more airflow to the tables or delay it so that it keeps more air going into the engine longer.
I dialed in everything following the instructions from the tuning school documents. The fuel trims are within 1-3%(they still need some smoothing). The car still has the issue of overshooting idle target. Especially when the AC is on. Without AC on the computer will catch the RPM around 600 and bring it back up to 800. If the AC is on the car will catch its self around 200rpm and return to idle target or stall.
I played with the throttle follower and it helped slow the rapid dropping rpm. But even with the rpm gradually slowing towards idle. Once it reached idle target (800rpm) the engine rpm drops off below target.
The only way i was able to overcome this issue was to increase base air flow from 9.6g/s to 13g/s. When i did this the car retuned to idle smoothly. Both in park and while driving. But as the LTIT adjusted the car back towards 9.6g/s the car would begin to stall again. So i zeroed out the LTIT limits. So it wouldn't correct for the high base airflow. But this is the incorrect was of doing this.2004 CTSV retune idle issue.hptRetunring to idle stall.hpl
It won't go into adaptive idle until all of the throttle follower and cracker stop adding additional airflow. When its not in adaptive idle it won't make spark adjustments or idle trims of the iac or in your case throttle blade adjustments.
Ok so, i have had so many different instructions on how to adjust the throttle body. This is an LS6 with DBW. Everyone says when going from the stock 78mm TB to the LS2 90mm TB. The ETC scalar goes down. The books i have from The Tuning School said to move it up on a gen3 LS as well as a gen4.
So i just went to the garage and changed my scalar to .0295. (up from 0.0255) I also added a little bit of idle airflow. The car started right up and felt like it was idling smoother. I gave it a rev and it gracefully returned to idle. I turned the AC (normally all hell breaks loose when i do that). Car maintained a steady 800rpm idle without much dip at all during engagement. I gave it a rev and it returned to idle gracefully and then had a slight moment of increased idle (went from 800 to 950 or so) then returned to 800. So it seems maybe the scalar is the issue. Ill take a look at the follower and cracker to fix that bubble hopefully.
I drove the car around and did a quick pull (it normally always stalls returning to idle from hard throttle) and all was well. Car idled just fine. I noticed i am showing a little rich now. So i will have to redo my VE and MAF tables. But i hope this fixes the issue. The car seems to be running very well. I also see the LTIT removing some air. ill take a look at that once it cools down outside. Its 114 today in phoenix and my intake temps were pushing 170
I attached the log and tune. Let me know if you have any thoughts or comments. i appreciate your help and knowledge.
I know what you meant by the follower and cracker have to be at zero for adapt to take over. I added a lot of air to the follower to get it to stop dropping so fast and stalling. Thats why on the last log there was a little bit of air when the rpm made it to idle target. i fixed that once i got the scalar corrected.
I hate the OS in that car... If you don't enable and tune "rolling idle", if you log, you will notice that each time you clutch IN, all airflow adders minus base get stripped away. You need the cracker but it goes to 0. If you clutch in/neutral/clutch out quickly, you will see that it doesn't act the same. I am referring to operation when moving, not still.
i noticed that. every once in a while the car will still drop to 500rpm and then correct and return to idle. Its intermittent. I logged it and sure enough you push the clutch in and follower and cracker go right to 0. That's when the idle falls rapidly and attempts to stall.
The only way i have been able to fix this is to make the base airflow 14.5 g/s and make LTIT min limit 0. So when the STIT kicks in and it removes the extra 4 g/s of air its not long term and when i hit the gas idle target base will be 14.5 still. i feel like this is a bad aid fix but its the only way i have been able to get the car to not attempt to stall. the ETC scalar helped a lot though.
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