Hello, I have a stutter/stumble on moderate acceleration with my speed density tune. It is visible in the RPM graph in the attached log. I see that the EQ ratio is a little lean in spots, but before I go increase fuel, I am hoping someone can help identify the cause of the stumble or confirm it is from the lean condition. I appreciate the help.
60percent_throttle.hpl
Last edited by b85chevy; 12-05-2022 at 07:16 PM.
my ss n/a stumbles in sd mode after the cam so i stay in open loop maf and my wife is even happy with how it runs
Something looks wrong with your timing--airmass doesn't look right.. Go to Airflow---Dynamic and make disable 8000rpm and reenable 7900rpm.
I would make P0101,102,103 all MIL on first error to fail the MAF
Go to Engine Diagnostics --Airflow-- MAF fail 2 (not 2,000) and enable 1, not 1,000
Are you sure you have a 3 bar GM Map sensor?
Last edited by Lakegoat; 12-05-2022 at 07:35 AM.
2000 Camaro SS 2015 L83 port injected, Whipple 3.0, 4L80E, 8.8 Ford
2013 Silverado 5.3, 6L80k 8.8
It feels odd there because you are making significant boost without being into PE. You need to work on your PE enable settings.
It's far to lean there.. To the point where you might can hurt something.
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Like the guy above me mentioned, you need to get this thing into PE MUCH sooner before you hurt this thing, and the stumble is because its lean as shit at 4-5 lbs of boost.
I would also change how you are failing the maf as the car will cold start much better and fail the MAF much quicker as well. Set the MAF fail high to 1, lower all of the tests right below it and set your dynamic to something like 8,000/7999
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Thank you all for the responses. PE was the issue, I guess the baseline tune PE settings needed some help. I tried a few changes to the PE throttle table, but that didn't seem consistent so I used the ZL1 PE parameters and those seem to be working well. Log attached.
60percent_throttle_2.hpl
Yesterday, with the SD only tune, I felt a stumble under normal driving with no throttle variation. I would appreciate some guidance on where I to look.
Attachment 126513
Attachment 126516
Attachment 126514
Last edited by b85chevy; 12-07-2022 at 08:35 AM.
Cannot tell much by the short logs.
This might be just normal tuning issues. Have you considered hiring a tuner?
Tuner at PCMofnc.com
Email tuning!!!, Mail order, Dyno tuning, Performance Parts, Electric Fan Kits, 4l80e swap harnesses, 6l80 -> 4l80e conversion harnesses, Installs
Complete log is attached.Attachment 126518
Last edited by b85chevy; 12-07-2022 at 12:02 PM.
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