Timing at idle

03TermiVert · Jun 2, 2020

Hooked up my programmer and it’s showing the timing all over the place. Seems to hover around 32 at idle but jumps up to the 40’s when reving the engine to 2k rpm or so then it dips down to 10 when I let off and levels out back in the low 30’s Seem wildly high but I honestly don’t know when I’m supposed to be monitoring it, is it only at wot that’s relevant? Any info is appreciated.

03cobra#2 · Jun 2, 2020

Should be lower at idle for sure. What rpm is your idle set at? Also what is your engine operating temp at when you took the reading? Finally how long was the car running for when you took the reading?

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SecondhandSnake · Jun 3, 2020

Sounds pretty close to what I would expect. Here's the borderline knock table for reference-

Granted that's only one table of several and there's dozens of adders and other functions, but you're in the ballpark. I would only really be concerned about it at higher load though.

01yellercobra · Jun 3, 2020

Can you log spark source on there?

03cobra_keek · Jun 13, 2020

You should be at around 16 to 20 at idle. What's it idling at

03cobra#2 · Jun 13, 2020

Just wanted to add that I've been working on my idle. I had it set to 900 because I have cams and spark was around 20. Idle surged so my tuner lowered it to 15 and made all the difference. I then lowered to 875 and it surged a bit, so I lowered spark to about 10-12 and it idles good. So it seems that when spark is too high idle can surge and even idle higher then what you set it to.

Edit: idle is a balancing act between throttle blade position, idle speed duty cycle, idle integrator, and spark. They all have to jive to get a good stable idle. ESPECIALLY with more aggressive cams.

SecondhandSnake · Jun 19, 2020

03cobra#2 said:
Just wanted to add that I've been working on my idle. I had it set to 900 because I have cams and spark was around 20. Idle surged so my tuner lowered it to 15 and made all the difference. I then lowered to 875 and it surged a bit, so I lowered spark to about 10-12 and it idles good. So it seems that when spark is too high idle can surge and even idle higher then what you set it to.

Edit: idle is a balancing act between throttle blade position, idle speed duty cycle, idle integrator, and spark. They all have to jive to get a good stable idle. ESPECIALLY with more aggressive cams.

FWIW with mine I initially had very little timing in mine, still using the old 2V tables that were down closer to 10-20 deg and it would surge. I updated it to the 4V tables (~40 deg) but what really made the difference is the spark gain and idle spark feedback. That keeps spark from swinging around a lot and made it nice and stable. It's critical with bigger cams.

03cobra#2 · Jun 20, 2020

Thanks for the tip with idle spark gain. I noticed mine was set above stock and my idle timing was jumping around. I lowered this back to stock. Let's see if that makes a difference.

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Timing at idle

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