is it lower "main spark advance" or is it "closed tps spark advance" that control the total idle spark advance?

My spark advace jumps all over the place on idle??

 

Closed TPS is for when the throttle is fully closed, timing.

Do you mean with a timing light, or when being scanned?
If with a timing light that's generally pretty much normal.

There's usually a min TPS to switch from closed throttle timing, often it's about 4% TPS.

 

So to answer his question, closed TPS spark advance is where he would probably want to add idle spark, globally, right? I think increasing the advance will somewhat tame the jumping vacuum signal (that's what's causing the jumping timing). Otherwise, you can try putting the same timing in several kPa cells around your idle rpm.

 

A lot of masks run a SA correction term to help with idle stability. If the mask you are using has this functionality it can be of help to reduce the amount of SA change vs idle speed change.

Else it starts chasing its own tail. Engines that have been upgraded with better heads and cam respond to a greater degree of SA changes. Hence the requirement to reduce this.

RBob.

 

If you look in the Tuner Cat 'Constant' table, you can find the limits that seem to set whether the ECM uses the Main Table, or the Closed Throttle spark table.

A discussion of other idle modifiers was here: http://forums.corvetteforum.com/zero...tid=1544158070

FWIW, the lower part of the Spark Table from a '92 Vette LT1 bin makes a pretty good starting point for an L98 with HotCam & 1.6 rockers.

HTH

 

so if I put my "closed TPS vs spark advance" to 28 degrees at 800rpm ( where i idle ). I have to change my main lower spark tabel also. Like 28 degrees at 800 rpm 30-60 kpa area?

 

28's a whole bunch for idle, unless your running a whole bunch of cam.

The more timing you run the more of a strain you put on everything. From bearing wear, and oil temps., into putting heat into the dome of the piston.

 

hmm ok i hear ya..

Any ide on where the "hot cam" whants in idle?
The strange is with my stock chip the idles whas fine, but super rich. When I got my blms at 128. The idle started to surge from 500 to 1100 when cold. My next test is to smooth out the lover main spark tabel at idle ( 800 rpm 30-60 Kpa ), so i run 26 all the way.

 

Here is what I show for an LT1. The upper numbers will be difficult to make without your EGR enabled:

 

with the upper number you mean load rpm or just hig advance?

thanks by the way

 

Say there, Fish, here's my tuning tip for the day:

I took the time to read your questions before I posted answers.

How about you take the time to read the answers BEFORE you ask another question? If you don't read the answers, there really isn't much point in me posting them, is there?

 

nice tip. I dident se the hole picture before.
sorry for that..