Need tune help I know this is C5 section

[RLSebring]

I have worked on my tune for some time and with various help have the car running very well except at idle.

Car is 08 A6 LS3 Hot Cam specs are .525 lift and Duration @.050 intake is 219 and exhaust is 228 Gear is 2.56

The car lurches and lunges in a time able cycle when sitting still. Depending on the setting it does this both in Park and drive as well as neutral. And by time able I mean it can idle for about 10 seconds pretty smooth than start the lurching and lunging for about 20 to 30 seconds and return to a smooth (relatively speaking idle) then return to lunging again.

As soon as I step on the gas to go it runs like it should. Before I get too far It has been suggested that I may need to install a stall speed converter. This seems excessive at this point. I'm told that the converter may be too tight but I believe it should be able to be tuned out but will but will give in if necessary.

GMPP tells me it should idle just as good as a normal LS3. I have adjusted the Idle Air, Airflow and idle timing tables in small increments from the base LS3 tune all the way to almost LS7 numbers. I cannot seem to find a happy medium. It seems to go from a very rough idle in park to very rough idle in gear. The idle just seems like it run hard instead of a nice smooth feeling.

Most everyone tells me this is a fairly big cam and needs lot s of idle air. The stock idle air:

200 400 650 800 1000 1200 1600 2000 2500 3000 3500 4000 4500 5000 6000 7000 8000
1st Gear 1.0582 0.8598 0.8598 0.9259 1.0184 1.0913 1.1427 1.2564 1.4628 1.7010 1.9836 2.2893 2.5729 2.7440 2.9101 2.9101 2.9101
2nd Gear 1.0582 0.8598 0.8598 0.9259 0.9259 0.9510 1.1303 1.1665 1.3344 1.5550 1.8090 2.0942 2.3688 2.5135 2.6455 2.6455 2.6455
3rd Gear 1.0582 0.9590 0.9590 0.9590 0.9590 0.9590 1.1070 1.1225 1.2998 1.5220 1.7480 1.9472 2.1668 2.2583 2.3810 2.3810 2.3810
4th Gear 1.0582 0.9259 0.9259 0.9259 0.9259 0.9396 1.0939 1.1094 1.2690 1.4889 1.7150 1.8881 1.9968 2.0609 2.1164 2.1164 2.1164
5th Gear 1.0582 0.8598 0.8598 0.8598 0.8598 0.9350 1.0797 1.0900 1.2667 1.4889 1.7150 1.8881 1.9968 2.0609 2.1164 2.1164 2.1164
6th Gear 1.0582 0.8598 0.8598 0.8598 0.8598 0.9350 1.0797 1.0900 1.2667 1.4889 1.7150 1.8881 1.9968 2.0609 2.1164 2.1164 2.1164
Neutral 0.7937 0.6614 0.7937 0.7937 0.8267 0.9259 1.0582 1.1905 1.3228 1.4551 1.5873 1.5873 1.5873 1.5873 1.5873 1.5873 1.5873
Reverse 1.0582 0.8598 0.8598 0.9259 0.9259 0.9510 1.1303 1.1665 1.3344 1.5550 1.8090 2.0942 2.3688 2.5135 2.6455 2.6455 2.6455
Park 0.7937 0.6614 0.7937 0.7937 0.8267 0.9259 1.0582 1.1905 1.3228 1.4551 1.5873 1.5873 1.5873 1.5873 1.5873 1.5873 1.5873

I am currently at:

200 400 650 800 1000 1200 1600 2000 2500 3000 3500 4000 4500 5000 6000 7000 8000
1st Gear 1.6762 1.3620 1.3620 1.6134 1.7744 1.5847 1.5512 1.6201 1.4941 1.7010 1.9836 2.2893 2.5729 2.7440 2.9101 2.9101 2.9101
2nd Gear 1.6762 1.3620 1.3620 1.6134 1.6134 1.3809 1.4147 1.5005 1.3750 1.5550 1.8090 2.0942 2.3688 2.5135 2.6455 2.6455 2.6455
3rd Gear 1.6762 1.5191 1.5191 1.6710 1.6710 1.3923 1.3977 1.4664 1.3419 1.5220 1.7480 1.9472 2.1668 2.2583 2.3810 2.3810 2.3810
4th Gear 1.6762 1.4667 1.4667 1.6134 1.6134 1.3641 1.3732 1.4401 1.3150 1.4889 1.7150 1.8881 1.9968 2.0609 2.1164 2.1164 2.1164
5th Gear 1.6762 1.3620 1.3620 1.4982 1.4982 1.3577 1.3610 1.4277 1.3091 1.4889 1.7150 1.8881 1.9968 2.0609 2.1164 2.1164 2.1164
6th Gear 1.6762 1.3620 1.3620 1.4982 1.4982 1.3577 1.3610 1.4277 1.3091 1.4889 1.7150 1.8881 1.9968 2.0609 2.1164 2.1164 2.1164
Neutral 1.3827 1.1525 1.3827 1.5209 1.5300 1.5235 1.5199 1.6160 1.4261 1.4551 1.5873 1.5873 1.5873 1.5873 1.5873 1.5873 1.5873
Reverse 1.4439 1.4850 1.5269 1.7423 1.7106 1.5930 1.5708 1.6478 1.5509 1.6240 1.8170 2.0919 2.3360 2.5109 2.6130 2.6455 2.6455
Park 1.3827 1.1525 1.3827 1.5212 1.5212 1.4788 1.5199 1.6160 1.4261 1.4551 1.5873 1.5873 1.5873 1.5873 1.5873 1.5873 1.5873

I have ran the idle timing portion from 600 to 2000 rpm’s from 13 degrees to 35 degrees with no noticeable differences. Here is where it stands now:

Labels 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400
0.08 35.5 35.0 35.0 35.0 35.0 37.0 40.0 41.0 42.5 45.5 45.5 45.5 45.5 45.5 45.0 45.0 45.0 45.0
0.12 35.5 35.5 35.5 35.5 35.5 37.5 41.0 42.0 44.0 45.0 45.0 45.5 45.5 45.5 45.0 45.0 45.0 45.0
0.16 35.5 35.5 35.5 35.5 35.0 37.5 41.0 42.0 44.5 45.0 45.0 45.5 45.5 45.5 45.5 45.0 45.0 45.0
0.20 35.5 35.5 35.5 35.0 35.0 37.0 40.5 41.5 42.5 44.5 45.0 45.5 45.5 43.5 43.0 43.0 43.5 43.0
0.24 30.5 30.5 30.5 30.5 31.5 33.0 35.0 38.0 40.0 42.0 44.5 45.0 45.0 43.0 43.0 43.0 43.5 42.5
0.28 25.0 25.0 25.0 26.0 27.5 30.0 32.5 35.0 37.5 39.0 41.0 42.0 42.0 41.0 41.5 41.5 41.5 41.0
0.32 21.5 21.5 21.5 22.5 24.5 27.0 30.5 33.0 35.0 37.0 38.5 39.0 39.5 38.5 39.0 39.0 39.0 39.0

I was in the process of changing the injector flow rates as I believe they are set to LS3 and not LS7 sizes but my MVPI cramped out so I am waiting on a replacement. Any input would be greatly appreciated.

I will attach my tune if anyone wants to look into it and make any suggestions. My goal at this point is to smooth out the idle. I don’t expect it to be perfectly smooth but am looking for something far better than it currently is. http://www.hptuners.com/forum/showth...553#post190553


I'll be cross posting in Tech an C5 tunes.

[tblu92]

I would set the in gear/PN idle to around 750-800 RPM's--I don't know what software you are using but The correct air table is the "desired airflow table" i would not mess with any of the others--if you did-put them back to stock--Try adding about 15% to both the In gear and P/N tables
The "commanded open loop table -normal" is the AFR used when making cold and warm starts---A cold start uses a min coolant temp to switch to closed loop--A warm start uses a timer--Typically you must ADD some fuel in this table to help it from surging--The stock table for a cold start for example may be around 15.50 AFR for a temp say at 75* try richening the fuel in this immediate area to something like 15.25--Only do this in the lower fuel columns used generally for starts--
Don't know if an 08' has a throttle follower table--if it does you need to remove a % in both P/N and in gear in the decay rate
--start with 10%
A good add for timing is usually about 3* for the "base timing" for In gear and P/N
Problems occur with a cam and a stock converter because you must idle the engine higher to get it to idle smoothly--BUT when you do this the car requires lots of brake effort to hold it at a light---A looser atall converter eliminates this issue beacuse at an 800 idle it won't creep and requires little brake effort

[RLSebring]

Thanks for the good information. It's looking like one of my first changes will be to up the idle. I didn't really want to but your probably the 5th or 6th person to recommend it. I expect my replacement HP Tuners interface to arrive tomorrow and I can get in to make some changes asnd be able to report what the changes are doing.

Thanks again I really do apprecuiate the input.

Originally Posted by tblu92

I would set the in gear/PN idle to around 750-800 RPM's--I don't know what software you are using but The correct air table is the "desired airflow table" i would not mess with any of the others--if you did-put them back to stock--Try adding about 15% to both the In gear and P/N tables
The "commanded open loop table -normal" is the AFR used when making cold and warm starts---A cold start uses a min coolant temp to switch to closed loop--A warm start uses a timer--Typically you must ADD some fuel in this table to help it from surging--The stock table for a cold start for example may be around 15.50 AFR for a temp say at 75* try richening the fuel in this immediate area to something like 15.25--Only do this in the lower fuel columns used generally for starts--
Don't know if an 08' has a throttle follower table--if it does you need to remove a % in both P/N and in gear in the decay rate
--start with 10%
A good add for timing is usually about 3* for the "base timing" for In gear and P/N
Problems occur with a cam and a stock converter because you must idle the engine higher to get it to idle smoothly--BUT when you do this the car requires lots of brake effort to hold it at a light---A looser atall converter eliminates this issue beacuse at an 800 idle it won't creep and requires little brake effort