Ok so i hooked up a scan tool to my 03 monte carlo ss 3.8L N/A today and the timing advance is 20 degrees at idle and goes up to around 30ish on accel and down to 15-18 when i let off the gas. Im curious as to if this is good or bad? Im planning to hook up my dads and see what it reads but im still curious. Also the short term fuel trim reads off as 0.8% at idle and goes negative as i accel as well. This might be because of the fact i had to put 93 in it because the station ran out of 89 (i use it for mpg) but it pulls back from -7% to -3%. Im curious if this is good or bad as well. Can anyone provide any info?

 

It should lock in around 28-30* of timing IIRC at WOT. You possibly have a small vacuum leak (your fuel trims are a little rich). Overall you're not in too bad of shape, check all your vacuum lines on the engine - a lot of those rubber T's and elbows like to crack.

 

Ill end up checking the vaccuum lines for leaks in the summer. Its still too chilly out right now to do it around here. It could be from my intake since it comes eith a hole and pipe for a pcv line but our cars have it under the map so i just stuck a bolt through it so it might be leaking out of there. Still looking for a solution there. As for the fuel ill check again when i go back to my normal fuel but thank you for your help!

 

wot NA timing is more like mid 20's when tuning you can push up to 27-30* but i never needed to when i was na. also switch to 87! i did extensive tuning and trial and error on mine and never saw any gain or ability to add timing on higher octane when NA. my 14.9 run was on 87! and got pretty good mpg too.

 

Agreed, mine has a custom tune with 3 degrees advance (premium fuel only) and pulls in the high 20's at WOT...