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Hitting Spark Cut in Cruise

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Old Sep 8, 2024 | 12:22 AM
  #1  
Caverly's Avatar
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From: NH
Default Hitting Spark Cut in Cruise

Long time lurker finally doing something.

I installed an MS3Pro PNP with an Innovate MTX-L+ and a Napp Motorsports intake. I rescaled the base map for an NA application, set my base timing, calibrated everything, and set off to autotune VE.

Here's my issue: In 5th gear, I'm hitting spark cut while cruising. It doesn't seem to happen in lower gears at the same or lower speeds. I'm not really sure what's setting it off.

Can I get some help going through the attached tune and log? Note that I've changed the VE since this drive. Sorry for the length of the log, it's a whole 10 minute drive. The cruise spark cut I'm referring to happens at 282s, 285s, 299s, 332s, 343s, 367s, 440s, and 503s.
Attached Files
File Type: msq
EOD Saturday.msq (285.5 KB, 18 views)
File Type: mlg
2024-09-07_18.35.01.mlg (3.13 MB, 26 views)
Old Sep 8, 2024 | 10:08 AM
  #2  
curly's Avatar
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I've looked at the first few instances, and I'm fairly certain that's your AFR safety system activating. You're fairly lean through the entire log. Turn that off while you're tuning, but start adding that fuel in.

Here's what I came up when I put the log through VE analyze on MLV. Anything blue means more fuel has been added, red has been leaned out. It's mostly blue in the cruise areas.

Your ignition timing correction is also backwards. Adding timing increases RPM, and vise versa, which helps stabilize idle RPM. Your tune has it removing timing when it's below target, it should be increasing.

You're also running pretty cold, max temp in that log was only 179.


Old Sep 8, 2024 | 07:43 PM
  #3  
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That makes sense, thank you. I took it back out today with a new AFR target table and a richer VE table. I left the AFR safety system on since I'm still pretty new to this, but it didn't get triggered today.

Originally Posted by curly
Your ignition timing correction is also backwards. Adding timing increases RPM, and vise versa, which helps stabilize idle RPM. Your tune has it removing timing when it's below target, it should be increasing.
Weird. I hadn't touched that, so that's what DIYAutoTune is shipping it with I guess. I flipped it like you said.

Originally Posted by curly
You're also running pretty cold, max temp in that log was only 179.
Guess I'm adding a thermostat to the list.
Old Sep 8, 2024 | 10:14 PM
  #4  
curly's Avatar
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FYI I typically don't enable AFR safety. There's too many times when over run fuel cut or something else triggers it when I don't want it to.

Pay for the full version of MLV and TS, and start taking really long logs. Put these logs through MLV with your latest tune, it'll perfect your fuel table real quick.
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