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Old 02-08-2018, 08:02 AM   #1732
Scooby Specialist
Member#: 327563
Join Date: Jul 2012
Chapter/Region: MWSOC
Location: Cincinnati
2018 Civic Type R


Originally Posted by Scoobman20 View Post
Hey everyone. I'm struggling to figure out where this lean spike is coming from when I reach boost. I replaced the header gaskets and j-pipe gasket thinking it could be an exhaust leak above the O2 sensor, but no improvement. I also looked over the intake and intercooler couplings. Could this be blow-by from AVCS or some other leak? My other concern is my calculated load seems higher than quite a few logs I'm seeing with similar mods.

Here is the OTS Stage2 Big SF -

Here is the same map with an OL MAF re-cal and the CL delay reduced and CL map high load changed slightly (better but the spike is still there in the beginning) -

Mod List:
Catless J-pipe
3" Catback
Cobb 3" intake
TGV delete
EGR delete
Restrictor pill delete
I don't see a spike. I see one log that is lean the entire time and another that is lean for a good portion. The only spike I see anywhere is the Command spike at CL/OL switch which is common. I think you're looking at the wrong end in terms of problems. It appears you have either a scaling issue or a leak in the intake tract. Even the closed loop portion of your log has a very large correction being applied. Almost 24% before the transition. You go from -8% to +25% total fuel in the span of 2000RPM.

If you're using the same valve timing with the factory TGV Open side I don't see AVCS causing these issues. TGV would be normally open in that region. So unless you're changing valve action it shouldn't be an issue. If you have reset to the Cobb OTS for that parameter and see if it changes.
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Last edited by ericdet; 02-08-2018 at 08:08 AM.
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