Why is my idle spark so drastic???
Thread Starter
Joined: Dec 2005
Posts: 347
Likes: 15
From: Box Elder, SD
Why is my idle spark so drastic??? Look at this short log, I am playing hell with the idle on this car. I thought the spark would be more constant, changing only a few degrees at idle, but this thing is all over the place, even in closed loop.
Jack
Jack
Yes, there is adaptive idle overspeed and underspeed
spark adders vs RPM error, you should have these
tables. Some models have stupid stuff in them but
in general you want them. However if you zero the
adaptive spark while doing your idle tuning you will
be working more with the core problem, and not
having the adaptive spark busy "helping". If the
motor is pretty stable without adaptive spark then
it should be rock solid, with, when you set it back
to active.
spark adders vs RPM error, you should have these
tables. Some models have stupid stuff in them but
in general you want them. However if you zero the
adaptive spark while doing your idle tuning you will
be working more with the core problem, and not
having the adaptive spark busy "helping". If the
motor is pretty stable without adaptive spark then
it should be rock solid, with, when you set it back
to active.
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Those tables are there to help your car run better. Why remove something that's helping you? If you want to find the best idle spark just use the VCM controls which will lock in your desired timing at idle.
You guys have to realize you are going to be wasting your time to perfect your tune. Take advantage of what is helping you, don't fight it.
You guys have to realize you are going to be wasting your time to perfect your tune. Take advantage of what is helping you, don't fight it.
That's true ghost, but my idle spark will jump from 22 degrees to 36 degrees on cold startups and start to oscilate with the motor and I think it's causing the motor to hunt from 600-1200 rpm for the first 30 seconds after startup. I don't plan on eliminating it, I just plan on toning down how much of an impact it has on initial startup and see if that helps reduce the rpm swing.
Also part of my issue is I've been battling with my idle, and part throttle 'surge' since adding the ported FAST and a Fidanza flywheel at the same time.
I'm not exactly sure how the two impact each other, but I know that dropping over 16lbs off the flywheel impacts idle and low rpm drivability. Now if I can just figure out what the hell I'm doing, I'll be happy.
I'm not exactly sure how the two impact each other, but I know that dropping over 16lbs off the flywheel impacts idle and low rpm drivability. Now if I can just figure out what the hell I'm doing, I'll be happy.
As Jimmy said, I only zero it out when I need to dail in the RAF and any other idle airflow model. Once the car can idle relatively smooth without idle spark correction, I will either set it back to stock or custom make one for the cam. I prefer to not have the idle spark jump around so much to control the idle and be as steady as possible. This way if I do need extra spark to maintain the idle, I know I have room for it. Rather then the spark be jumping to/from 18-26 degrees and cause a stall condition. Idle spark correction should be used as your last resort to keeping the idle steady, it shouldn't be used as the primary method of stabilizing the idle, JMO. 
My spark idle (with an F13) is steady at 24 degrees, with very few -1 or +1 degrees of idle spark correction.
My spark idle (with an F13) is steady at 24 degrees, with very few -1 or +1 degrees of idle spark correction.
That's true ghost, but my idle spark will jump from 22 degrees to 36 degrees on cold startups and start to oscilate with the motor and I think it's causing the motor to hunt from 600-1200 rpm for the first 30 seconds after startup. I don't plan on eliminating it, I just plan on toning down how much of an impact it has on initial startup and see if that helps reduce the rpm swing.
I'll figure it out eventually.
Here is what I'm talking about. Look at my log and you'll see that for the first 30 seconds, my idle and spark are all over the place and then it magically (to me at least) returns to normal and smooths out to a nice 875 rpm with the timing ranging from 26-30.
I wouldn't think a 224 needs more than 23~24* to idle in an M6 application...
Also, did you disable the AIR compesation? On start up, IAC and spark do some funny things that were originally there for the air pump. Make sure all of your spark and IAC modifiers are where they need to be.
You may need to redo your RAF table to compliment the spark change.
Also, did you disable the AIR compesation? On start up, IAC and spark do some funny things that were originally there for the air pump. Make sure all of your spark and IAC modifiers are where they need to be.
Also, did you disable the AIR compesation? On start up, IAC and spark do some funny things that were originally there for the air pump. Make sure all of your spark and IAC modifiers are where they need to be.
What else do I need to address for AIR compensation?
