From my brief experience with idle on the 165, I found that the constant spark advnace of around 26deg of total advance gave the most consistant idle from my hotcam. I am now running 730 and my idle isn't nearly as consistant as 165 was. My total advance varies from 18-28deg and for diagnostic purposes, I would like to disable all idle spark correction. I see four tables that have to do with it, Idle SA advnace vs. rpm error, idle SA retard vs. rpm error, idle sa advance multi vs. map, and idle sa retard multi vs. map. Should I just leave the multipliers at 1 and zero out the other values? Thanks

 

I ran into a lot of the same concerns/problems that u have.. Mine boiled down to 2 main things. First one was getting as many idle cells as correct as humanly possible in the idle area of the VE table and playing with the timing in the idle area of the MSA. Also included alot of time playing back forth between fuel and spark till i found what it liked.

I havent played with the other idle tables that u have mentioned, but do what grumpy preaches and set your iac to where u want it to idle at to keep it out of the loop as much as possible. I did some playing around with this and once i got it spotted to where the eng lliked, my idle did tend to improve greatly(still flutters from the lope but almost unavoidable i think).

After doing all the above to my car fro a 600 rpm idle in gear and working up to 800 idle in gear and then going backwards. what i think is the best idle i can achieve is set a 738?(or very close to) hot and in gear
my two cents
hope it hepls u out some
Jeremy
PS were close enuff to compare notes pm me and we can check it out

 

Funny you should pick an "unobtainable" idle speed where the ECM must cycle between 725 & 750.

I too have found a preference for an "unobtainable" idle speed that the ECM can't deliver. I found the oscilation of the ECM constantly adding/subtracting made a really stable and smooth idle.

Has anyone else experimented with the "odd" idle speed numbers?

 

Wow i got a compiment by glenn(how r u doing lately by the way?).. I dont know i just played with from a slow a idle at X advance and worked my way up till it wouldnt stop when i wanted to slow the car down and went back down and worked a certain advance at a time and just kinda found that for some reason 738 rpm got it to what i would call the best obtainable idle for my cam

I didnt keep digging farther but now that u meantion it, u r right it goes by 25 rpm increments on my diacom readings.

hey even us computer simpletons find a slution thru trial and error
later
jeremy

 

Not idle, but because of the tables mentiones in the first post, I went ahead and added some new tables to my TDF. Results are here... http://expert.ics.purdue.edu/~msandi...SA_TEST_02.xls

I have a more stable idle using all the same values in the retard table, as opposed to the advance table (if you look to see where GM put the 0 SA when you check out the 2 tables, I flipped it to the other table). Of course, this depends on if you are usually over or under, and probably varies as much as the food we had for dinner. I know one day of testing isn't enough, but its a start.

 

Good info bro, I zerod out the values in the retard and advance tables and found that idle didn't improve any, actualy seemed worse, so the values need some tweaking. I should have a few hours tomorrow to test, Ill post some findings.

 

Either my car is inconsistent, or messing with that retard table really soured my drive around town. I drove around the backroads for about 30 miles tonight with test D BIN in and low end seemed a bit less there, mainly from a stop. I added ‘traction control’ without even trying. Back to GM specs for the meantime.