Timing jumping all over at idle
Thread Starter
TECH Fanatic
Joined: Aug 2005
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Timing jumping all over at idle I have a 5.3 with a Futral F113 cam. At idle around 850 rpm the timing is jumping all over from about 7 degrees to about 28 degrees. Is this normal? I just started playing with the hp tuners but i didnt expect to see the timing jumping like this. Car is not on the road yet.
If this is not right what should i be switching to stabilize the timing?
If this is not right what should i be switching to stabilize the timing?
Underspeed and overspeed spark correction are active.
The more unstable your base tune is, the more they
need to boogie to keep the RPMs flat. But some years
have really stupid stuff in the underspeed table, like
too much underspeed and the correction "just quits"
making the thing hysteretic and prone to large scale
oscillation.
You should always tune with adaptive spark zeroed,
so you see the real nature of the air / fuel / spark
situation, and re-enable adaptive spark after it's all
done, with clean and sensible profiles, for drivability
and robustness-to-minor-drift.
The more unstable your base tune is, the more they
need to boogie to keep the RPMs flat. But some years
have really stupid stuff in the underspeed table, like
too much underspeed and the correction "just quits"
making the thing hysteretic and prone to large scale
oscillation.
You should always tune with adaptive spark zeroed,
so you see the real nature of the air / fuel / spark
situation, and re-enable adaptive spark after it's all
done, with clean and sensible profiles, for drivability
and robustness-to-minor-drift.
Thread Starter
TECH Fanatic
Joined: Aug 2005
Posts: 1,004
Likes: 0
Thanks for those tips. I think i will get to work on it on tomorrow night or saturday. I think i have alot of work to do and a steep learning curve. LOL.
The timing does fly all over the place and i thought maybe it was the underspeed and overspeed correction. I will have to dig deeper into the tune and further try more options out to get my idle in order. It idles nice and choppy but rich even though 15.0-1 is commanded.
I havent spent much time on HP tuners yet. Rookie. I am sure it shows.
The timing does fly all over the place and i thought maybe it was the underspeed and overspeed correction. I will have to dig deeper into the tune and further try more options out to get my idle in order. It idles nice and choppy but rich even though 15.0-1 is commanded.
I havent spent much time on HP tuners yet. Rookie. I am sure it shows.
That's a lot of correction IMO Have you had it apart recently? You may want to check all your vaccum lines etc. That much correction through overspeed/underspeed leads me to believe you have a slight vaccum leak somewhere
