Idle spark

[0081(2)]

I was reading the 12P tuning guide (im not running 12P rather using it just a general tunning guide) and it talked about matching idle spark and with what the car is idling at in the main spark table.
Im using a flash pcm in my VY with the enhanced code

So it said drop the main spark down or increase the idle spark table so they are matched. I checked my tables the the idle is 15.47 and in the main stable it would be sitting around the 35 degrees mark. It sounds odd to increase the idle spark by around double, i do have a cam and increased it to 25 and it idles much better so should i keep going and increase it to they are the same is not ?

[Dylan]

Your main spark table has 35 degree that low down? What rpm and kpa does it idle at?

[0081(2)]

Your main spark table has 35 degree that low down? What rpm and kpa does it idle at?

I'm running the enhanced MAF code and it idles around the 800 rpm mark and around 150 MGC. My car is a factory manual so it has a higher spark table then the auto's from that i have seen.

Its about the 35 degrees mark on the main table it moves around slightly.

Should i move it up at bit more ???

[Dylan]

oops maf, out of my league. On 12P I match the idle and main tables. Example 800rpm 50kpa idle. idle table might be 26 degree so match that to the main table and blend into the rest. Makes for a smooth transition in and out of idle.

[0081(2)]

Might bring the main down a bit and the idle up a bit then blend it all

[Holden202T]

yeah the tuning guide is totally based on MAP tuning, how much of it you can actually use in a MAF setup im not sure .... im also not sure if the MAF tunes do the same stuff with idle and main spark like the 808 does ...

[antus]

I think for a MAF tune you with a cam you want to look at desired airflow, increase that if the cam struggles down low. you can open the throttle just a fraction or the butterfly stop to make it idle how you want then check the logs for how much air flow is being logged and update the tune to target that airflow at idle in that gear. I dont recall off the top of my head what the scalars are to do this though.

[0081(2)]

It did struggle a bit at idle on 15 ish degrees and ran about 45 iac steps but when i increased it the spark to 25 it idles much better and the iac dropped to 20.

I know the guide is for map but at least give a but of an idea no guide for the maf stuff yet

[ejukated]

same concept applies for MAF, lower mgc is the same as lower MAP. desired airflow is more of a rolling idle thing although it also uses it for some other 'idle' conditions. That's why people struggle with MAFs coming from a MAP based system, you can fudge it in so many places to get ok fuelling with no real bad consequences but on a MAF system its all integrated so the airflow part has to be right, the injector cal etc.

If you ever get to do modern stuff 2006+ you can easily blow a trans on a blown combo by having a bad MAF or VE table cal

[The1]

or change in TPS/TB