Cruise AFR and timing
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TECH Regular
Joined: Jun 2013
Posts: 487
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From: Orange, Texas
To come back and post a resolution to this, it turns out this was a symptom of another problem, clogged injectors. In my thread here https://ls1tech.com/forums/forced-in...-out-fuel.html is where I figured it out with some help.
Injectors had trash in the top of them from the build so I took them out and cleaned them. Car is running faster than ever now and I'm working to re-tune the fuel map. It's cruising just fine in the 14.7 range now and I'll likley lean it out some more with fine tuning.
Injectors had trash in the top of them from the build so I took them out and cleaned them. Car is running faster than ever now and I'm working to re-tune the fuel map. It's cruising just fine in the 14.7 range now and I'll likley lean it out some more with fine tuning.
Last edited by squarles67; Nov 11, 2017 at 04:38 PM.
Thanks for posting a resolution!
Also, keep in mind that an ignition misfire will present itself as a lean condition and the Holley will add fuel. I realize this wasn't your problem, but I'm just throwing it out there in case someone is experiencing this...
Andrew
Also, keep in mind that an ignition misfire will present itself as a lean condition and the Holley will add fuel. I realize this wasn't your problem, but I'm just throwing it out there in case someone is experiencing this...
Andrew
best way to dial in cruise a/f and timing is using cruise control,
set cruise at some speed Xmph (lets say 40mph)
log injector duty, engine vacuum, and speed (miles per hour which we said was 40)
Let it log long enough to generate a field of data, the lowest and highest points for both injector duty and engine vacuum (the road is not perfect)
Once you've collected enough data, adjust your a/f or timing slightly.
and re-log the same exact way at the same speed.
The best a/f and timing will result with lowest injector duty cycle, which you will need to combine with engine vacuum to determine overall injector flow rate (for referenced fuel pressure regulator systems which I always run).
and as a bonus, if you were logging EGT it should also go down as you dial in proper a/f and timing, even if you are removing fuel and engine is getting leaner.
set cruise at some speed Xmph (lets say 40mph)
log injector duty, engine vacuum, and speed (miles per hour which we said was 40)
Let it log long enough to generate a field of data, the lowest and highest points for both injector duty and engine vacuum (the road is not perfect)
Once you've collected enough data, adjust your a/f or timing slightly.
and re-log the same exact way at the same speed.
The best a/f and timing will result with lowest injector duty cycle, which you will need to combine with engine vacuum to determine overall injector flow rate (for referenced fuel pressure regulator systems which I always run).
and as a bonus, if you were logging EGT it should also go down as you dial in proper a/f and timing, even if you are removing fuel and engine is getting leaner.
I keep finding that the newer square port cylinder head LS3 doesn't like much timing, having a max around 26*, has anyone else found this to be true as well, sounds strange that a head can affect timing events so much compared to other LS motors.... so far I'm still working on this
I keep finding that the newer square port cylinder head LS3 doesn't like much timing, having a max around 26*, has anyone else found this to be true as well, sounds strange that a head can affect timing events so much compared to other LS motors.... so far I'm still working on this
I keep finding that the newer square port cylinder head LS3 doesn't like much timing, having a max around 26*, has anyone else found this to be true as well, sounds strange that a head can affect timing events so much compared to other LS motors.... so far I'm still working on this
Sounds about right. They don't like/need very much timing.
