smooth idle attempt

[LNFnewb]

Do you have cat heating enabled or disabled?

[stromboli86]

It says disabled, that was one of the good starts when cold. Every now and then the log shows the Inj. Pulse width rise while Rpm's are dropping and then it loads up causing the car to shake and sputter... I cant figure out what is behind the rising inj pulse, very annoying

[LNFnewb]

It says disabled, that was one of the good starts when cold. Every now and then the log shows the Inj. Pulse width rise while Rpm's are dropping and then it loads up causing the car to shake and sputter... I cant figure out what is behind the rising inj pulse, very annoying

would their be any problems with disabling it even though I do have an aftermarket catted downpipe?

[stromboli86]

it should be fine, you will probably have to rework the idle some after it tho

[|V3nom|]

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?!

is this bad lol?

im catless btw if that helps any.

[stromboli86]

Im not sure Venom, lol

Does your fuel pressure ever oscillate at idle when warm? should look like a bunch on ramps in a row and under the hood you will here the solenoid go click... click...click at idle and speed up rapidly when the throttle is touched. At least that is what mine does!

[stromboli86]

heres where i am now with my warm idle, seems pretty happy! i dont know which log it was but even when i turned on the A/c the car kept timing up and didnt freak out too bad. Iv also managed to have 3 cold starts of 50 degrees or less in a row where it didnt bog down! (knock on wood
)

[|V3nom|]

yeah when its warms it does the ramps motion. is it supposed to do that? during a cold startup the fuel pressure desired and actual stay parked but once the ect hits 140*~ it starts fluctuating like that. i need to log another cold start since its getting colder now to see what it does.

[stromboli86]

yea thats normal, i just didnt scroll far enough through the log lol.

[Dayhoff35]

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

Thank you i no longer think im crazy lol, cars away for the winter for now :/. Ill be home in a few weeks and be able to mess with it more though.

[Dayhoff35]

heres where i am now with my warm idle, seems pretty happy! i dont know which log it was but even when i turned on the A/c the car kept timing up and didnt freak out too bad. Iv also managed to have 3 cold starts of 50 degrees or less in a row where it didnt bog down! (knock on wood
)

no drop right after the start up? Screenshot?

[stromboli86]

Sure thing, i was referring more to the car RPM's dropping to 400 and back up but the drop you were asking about doesnt look too bad either lol. Finally getting a good grasp on how to change the tables.

[Dayhoff35]

Sure thing, i was referring more to the car RPM's dropping to 400 and back up but the drop you were asking about doesnt look too bad either lol. Finally getting a good grasp on how to change the tables.

ok good i dont have to hunt you down now lol, i still have mine at a smooth 10 have a new file but the car is 200 miles away so i cant flash it .

[stromboli86]

That sucks man, i still have some fine tuning to do but the way it is currently you wouldnt notice it while driving really... only when you review the logs. Depending on coolant temp the ign advance might be 20ish or as low as 12 but when warm it settles to a nice 15 degrees.

Also you wouldnt need to hunt me down, im pretty sure we are from the same state... i might be closer to your car than you are right now lol

[Dayhoff35]

I'm from maryland but in pa right now, where are you at?

[stromboli86]

Howard county, MD. Lots of old people where i live haha

[|V3nom|]

gonna try to post here tomorrow. finally was able to drive my car today after a couple of months, man it felt good!

[|V3nom|]

here we go. still choppy right at start up but settles down after a little bit.

[T-Man]

Has anyone considered messing with the Optimum Torque percentages around idle loads rather than messing with DALs and Optimum spark tables?

I wonder...

[stromboli86]

here we go. still choppy right at start up but settles down after a little bit.

Bump the 800RPM/30% load column in Optimum Spark up some to smooth it out, its jumping from 20% to 30% then back to 20% causing the big spikes and timing drops.

Iv heard mention of using the optimum torque table but never messed with it Tman, i used Opti spark, some DAL's and lots of testing