smooth idle attempt

[Freakotec]

I've personally had the best luck with dialing in a smooth idle with mine and other lnf's by playing a fine balancing act between dals, optimum spark and optimum torque, so T-man is correct in my eyes. I also seem to get the best results by aiming for 10-15* of timing at idle instead of 20* (although I'm sure a few will strongly disagree with that). Right or wrong, once I go beyond 15* during a warm idle it's never quite as smooth as I really like so I just stick to what works for me.

As far as cold starts go, especially for you guys in the colder parts of the country I would seriously think of reconsidering sticking with a locked in 10* intake cam angle like most seem to do and maybe try something else (I'm talking purely on cold starts mind you. Warm engine 10* int/-6*exh is obviously where you want to be). Try messing with the intake cold idle table and the corresponding factor table to allow for variences in cam movement for different temperatures during cold start. For me this made a huge difference in resolving any hard cold starting issues. For example, I'm sure you guys are very aware of how notoriously difficult cold starts can be particularly when running an ethanol blend. Lately in my part of the country we've had high temps topping out only in the teens, yet my car running e47 has had zero issues with cold starts and this is WITHOUT catwarmup enabled. Just a thought.

[Gremlin85]

Iv just recently started messing with my idle again seeing as the cold season has arrived and my car hates cold starts. Iv noticed quite a few things that i dont know if you guys noticed while reading thru new and old threads!

Starting with this one, Venom's car looks like he LOWERED Optimum Spark around idle and LOWERED DAL's significantly and this in affect made his spark timing very close to the actual Spark tables. What i also noticed on his log was a throttle angle of 1% at idle and his fuel pressure does NOT oscillate at idle... almost like what he has changed makes the ECM operate outside of idle?!

Now with my car my DAL's are close to stock/slightly higher, but i was doing what was suggested in GMtechs thread of RAISING the Optimum Spark around all the idle areas. Im currently at 13* or so and 2% ETC with a very short timing drop at initial start. My fuel pressure oscillates at idle when warm and im not near my actual spark timing maps in idle areas.

Dayhoff, If you look closely at GMtechs idle log he posted it actually does have the initial timing drop just his graphs are so far zoomed out you dont notice it.

So what do i gather from this... Could be very wrong haha... If you command less DAL, ECM starts with a more closed ETC which in turn will require more ign timing to achieve the desired idle RPM, then its a mix of the optimum spark and actual timing tables that determines what idle timing you float around. OR leave DAL's alone and raise Optimum spark, in my case i started 4*idle at 6% ETC and stock opti's, raised opti's up and now im 14* idle at 2% ETC. So 2 ways to do basically the same thing! My head hurts...

And as far as timing drops at start up, it looks like on mine that the only reason it drops is that the RPM's are above the desired so it keeps pulling timing until it gets to desired idle speed. Once at or near the target idle speed if you continue to see timing dips pay attention to the Airload, i bet its near a transition in tables like 30%. If you look at the stock Optimum spark tables there is a significant drop from 20% to 30%. When i raised the 30% cells my timing drops were less dramatic and less frequent.

Let me know what you guys think of all that rambling, hopefully it helps us understand this more than confuses haha

It all finally makes sense to me!

Thanks lol.

[|V3nom|]

another attempt. starts out with low advance but works it way up to a smoother 21.5-22.

[|V3nom|]

ok i got tired of chasing my tail so i decided to start back over with gmpp tables.

wheres the best place to start at?

[|V3nom|]

no suggestions?

[|V3nom|]

experimenting again.

btw this new layout is confusing when trying to add an attachment lol.