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
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

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

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

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

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

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

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

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

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

I am currently at:

200 400 650 800 1000 1200 1600 2000 2500 3000 3500 4000 4500 5000
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
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
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
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
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
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 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
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
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

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:

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
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
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
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
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
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
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

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.

pmj341

try increasing the final airflow 5% from 200 to 1200 rpm.

RLSebring

I have been all over the place on the final air all the way to 2.0 of course that was running real bad and had trouble with it finding idle again. I am trying to find out the WHY's of only going up to certain RPM ranges.

How are you suppose to let any particular write run? There are times I have had the idle perfect then the next day it would be running really bad again.

Thanks for any help.

Here's the tune link http://www.hptuners.com/forum/showth...553#post190553

thesubfloor

Send me a log (or several if you have them) and then I'll download your tune from the HPT site and take a look.

Christopher

edcmat-l1

Needs more idle timing. That will help a bunch to smooth out the idle.

I've said this several times in these E38 and E40 threads. the closer you have the idle timing to optimal, the less idle air you'll need.

RLSebring

Do you go into detail on which tables to approach in these threads and would searching E38 locate them? I am interested in lerning not just the app but the why also. Thanks

seevi

You may need more timing!

68RSSS

I vote for timing. "Bigger" cam will increase valve overlap, at the same time decreasing static (and low RPM) compression.

Hit it with 2 degree advance increments a time and see what happens.

edcmat-l1

My email is edcmat-l1@msn.com if you'd like to talk to me about helping you with your tune.

carlrx7

the lift on that cam is smaller than a stock ls3 cam, WTH? and your cam is not big. baby size, are you still trying to idle at 650? try bumping it to 750, then get that stablized, then lower it 25, stabilize it again. and repeat.

-carl

RLSebring

Thanks for the input. Chris (the subfloor) has me pretty close now and the small increments and stabilizing is the order of the day. I'm stuck at 800 RPM's at the moment but slowing getting there. Hopefully 750 or even 700 may be achievable.

Thanks