Lt1 surges between 1200-1800 with CC503 & Lt1 Edit

[96'bowtie]

Looking for some feedback on this one.

Car is 96 Y-body w/ CC503 cam, long tubes, auto, 52mm t-body, 11.1:1 CR. Using Lt1 Edit

Car runs well above 2000k, however from 1200-1800 just off throttle in the 50-60kpa range, the car
seams to gurgle/sputter when in that RPM range when held at steady RPM. I primarily notice this at low vehicle
speeds holding 30-50kmh.

The LH fuel trim is around -2 to -4 and the RH is around -10 to -12, not sure if that is related. There does not
appear to be a vacuum or exhaust leak.

Is it possible the cam overlap is causing the unburned fuel to be sent out the exhaust and the 02's a reading a rich condition
leading to the fuel pull from the Rh side?

Any thoughts or direction?

[MEAN LT1]

What gears are you running in the vette? It sounds like it could be cam surge. If it in fact is cam surge there are a couple of ways to get rid of it. One, is to put a numerically higher gear in it to keep you out of the dead zone. Another is to either give it some timing in that area or add some fuel. Both have worked in the past for solving cam surge. Shouldnt be too hard with a mild cam like that.

[96'bowtie]

The rear end is a 3.07.

This may be a basic question, but what is accuounting for the difference in lh and rh fuel trim?

Are there any ways in lt1 edit to assist with tuning for the cam overlap at the low end? I can smell fuel passing the the exhaust tips also.

Also not sure if am describing the problem correctly either. I am not too familiar with cam surge, but please correct me if I'm describing something different.


Thanks

[firebird_1995]

Sounds like cam surge. I had it too. I bought a mail order tune that had improvements done for part throttle driving and it got much better. I believe it was leaned out and had more timing added as previously mentioned.

[96'bowtie]

I know it sounds basics, but through which table in Lt1 edit would you remove or add fuel to that area during that condition?

[firebird_1995]

i cant say for sure on lt1 edit as im a tunercat user, but i would first try raising the "map threshold to enable WOT" to 70-80kpa. its in the ecm constants page. bigger cams will most likely never see the low stock setting, if it does it will be just off idle. then i would raise the timing in "main spark advance vs rpm vs map". only as an example, here is mine...
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
400 40.0 41.0 41.0 40.0 39.0 37.0 36.0 35.0 33.0 30.0 29.0 24.0 22.0 19.0 17.0 15.0
600 42.0 44.0 44.0 43.0 42.0 41.0 40.0 38.0 37.0 34.0 33.0 28.0 26.0 22.0 19.0 18.0
800 43.0 46.0 47.0 46.0 45.0 43.0 40.0 39.0 38.0 37.0 34.0 31.0 29.0 27.0 24.0 21.0
1000 45.0 48.0 48.0 47.0 46.0 44.0 42.0 40.0 39.0 38.0 35.0 33.0 31.0 28.0 26.0 23.0
1200 46.0 49.0 49.0 48.0 47.0 45.0 43.0 41.0 40.0 38.0 36.0 35.0 33.0 30.0 28.0 25.0
1400 46.0 50.0 50.0 49.0 47.0 45.0 43.0 42.0 41.0 38.0 36.0 36.0 33.0 31.0 29.0 27.0
1600 46.0 50.0 50.0 49.0 47.0 46.0 44.0 42.0 41.0 39.0 38.0 37.0 34.0 32.0 30.0 28.0
1800 46.0 50.0 50.0 50.0 47.0 46.0 44.0 43.0 41.0 41.0 39.0 38.0 35.0 33.0 31.0 29.0
2000 47.0 50.0 50.0 50.0 48.0 46.0 45.0 43.0 41.0 41.0 39.0 38.0 35.0 34.0 33.0 31.0
2200 47.0 50.0 50.0 50.0 48.0 46.0 45.0 43.0 42.0 41.0 40.0 39.0 36.0 35.0 33.0 32.0
2400 47.0 50.0 50.0 50.0 49.0 46.0 45.0 43.0 42.0 41.0 40.0 39.0 36.0 36.0 34.0 34.0
2600 47.0 50.0 50.0 50.0 49.0 46.0 45.0 44.0 43.0 42.0 40.0 39.0 36.0 37.0 35.0 35.0
2800 47.0 50.0 50.0 50.0 49.0 47.0 45.0 44.0 43.0 42.0 41.0 39.0 37.0 37.0 35.0 35.0
3000 47.0 50.0 50.0 50.0 49.0 48.0 46.0 45.0 44.0 42.0 41.0 39.0 37.0 37.0 36.0 36.0
3200 47.0 50.0 50.0 50.0 49.0 48.0 46.0 45.0 44.0 42.0 41.0 39.0 38.0 37.0 35.0 35.0

i wouldnt suggest leaning it out unless you have a wideband to see where the a/f ratio is at.