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I've never seen best manifold vacuum at 13 degrees on any LS I've tuned...they've always liked more. Now when the motor has a huge cam, that's when I'll pull timing out in the low speed cruise which calms down surging or bucking.
Ty for the reply, can you provide a little more color on why the cruise and idle is way off? I've built the spark curve from a tuners' suggestions. (see pic). I'm right in line with his cruise and low vac areas. I somewhat agree the idle is a little high, but if I lower it, it struggles to start. With my latest curve, it snaps off and is very responsive out of boost. The one issue I fixed was my base fuel pressure was low compared to the Holley base value. 36 vs 43.5.
Ty for the reply, can you provide a little more color on why the cruise and idle is way off? I've built the spark curve from a tuners' suggestions. (see pic). I'm right in line with his cruise and low vac areas. I somewhat agree the idle is a little high, but if I lower it, it struggles to start. With my latest curve, it snaps off and is very responsive out of boost. The one issue I fixed was my base fuel pressure was low compared to the Holley base value. 36 vs 43.5.
I wouldn't overthink it too much. Learn to read your plugs and you'll get it figured out much faster
Ty for the reply, can you provide a little more color on why the cruise and idle is way off? I've built the spark curve from a tuners' suggestions. (see pic). I'm right in line with his cruise and low vac areas. I somewhat agree the idle is a little high, but if I lower it, it struggles to start. With my latest curve, it snaps off and is very responsive out of boost. The one issue I fixed was my base fuel pressure was low compared to the Holley base value. 36 vs 43.5.
Starting has nothing to do with that table. There is a separate cranking timing parameter that is used until the RPM goes above 400 (this number can be changed).
In my experience, unless you have a really big cam, LS engines don't need or want 22 degrees at idle.
Sounds good, I'll continue to take plug readings and keep tuning.
The cranking param was originally at 19, I had to move that to 21. I'll play around with the idle chars also. I'm sure there is more stuff I need to learn. Thanks.
Sounds good, I'll continue to take plug readings and keep tuning.
The cranking param was originally at 19, I had to move that to 21. I'll play around with the idle chars also. I'm sure there is more stuff I need to learn. Thanks.
I've only ever ran HP and Dominator systems but I've only ever left it at 15 degrees. Put it back to 15 and see what happens. I wouldn't be surprised if that was your issue
Sounds good, I'll continue to take plug readings and keep tuning.
The cranking param was originally at 19, I had to move that to 21. I'll play around with the idle chars also. I'm sure there is more stuff I need to learn. Thanks.
You for sure don't want 21 degrees cranking. I would experiment with settings between 10-15 degrees.
Update spark curve. Followed advice here: added idle and cruise timing in the high rpm, low vac areas. Sloped off the low rpm, high boost areas. I think everything improved across the board. Pulls hard, gets into boost quick, and my idle issues have improved. When I quickly blip the throttle, it was almost stalling. Not perfect, but now snappier and rev happy. I'll have to run more logs but I observed no knock. The learn asking for way more fuel now, which is great.
would you mind posting that table in KPA instead of PSI?
@91 Z28 I did redesign my spark table to look more like yours. Additionally, I reduced the cranking params to 13 degrees. With not much tuning time, turned over fairly easily. However, the idle was around 21 degrees, even though I had much lower values at lower rpms. It did go back to the partial stall when blipping the throttle. Again, not much tuning time. I would say lowering the values did help though. When I have some more time, I will provide an update on the new spark table. Thanks.
@91 Z28 I did redesign my spark table to look more like yours. Additionally, I reduced the cranking params to 13 degrees. With not much tuning time, turned over fairly easily. However, the idle was around 21 degrees, even though I had much lower values at lower rpms. It did go back to the partial stall when blipping the throttle. Again, not much tuning time. I would say lowering the values did help though. When I have some more time, I will provide an update on the new spark table. Thanks.
That table looks like you've got 21 degrees at idle. Have you verified timing with a pointer and light?? Make sure to turn off idle spark when you do that too. Also on your little side window under "idle tuning" have your ignition timing and base timing channels in there too
That table looks like you've got 21 degrees at idle. Have you verified timing with a pointer and light?? Make sure to turn off idle spark when you do that too. Also on your little side window under "idle tuning" have your ignition timing and base timing channels in there too
When the static timing check is enabled in the software the idle spark control is automatically turned off.
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