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Old 02-23-2020, 11:15 AM   #1
Subakook
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Default Running lean during spool?

My tuner said my AFR is not right during 2nd and 3rd gear pulls.

It's plenty rich by peak boost it looks like but while spooling it appears lean. Should be hitting 11:1 by 10 psi and it looks like it delayed but gets to 10.4 afr in the top end.
This has stopped us from moving on to ethanol tuning

2013 sti with full cobb flex fuel setup with rails
Tgv deletes
1050x
Cobb/aem pump
Killerbee header
Stock airbox

I have tested for boost/vac leaks and exhaust leaks. New front o2.
Fuel Pressure is good it looks like in the logs.
Anybody ever had lean spool or just delayed afr? The car feels strong, does not have any misfire, cylinder roughness or knock.
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Last edited by Subakook; 02-23-2020 at 11:21 AM.
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Old 02-23-2020, 11:18 AM   #2
Subakook
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The issue appears in 2nd and 3rd gear pulls when starting at 2500-2800 rpm mostly I think.
2nd gear log I think it didn't even hit target afr he said. But 4th gear looked ok.
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Old 02-23-2020, 11:46 AM   #3
Subakook
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Last edited by Subakook; 02-23-2020 at 11:53 AM.
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Old 02-23-2020, 12:18 PM   #4
subaru_gc8
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Quote:
Originally Posted by Subakook View Post
My tuner said my AFR is not right during 2nd and 3rd gear pulls.

It's plenty rich by peak boost it looks like but while spooling it appears lean. Should be hitting 11:1 by 10 psi and it looks like it delayed but gets to 10.4 afr in the top end.
This has stopped us from moving on to ethanol tuning

2013 sti with full cobb flex fuel setup with rails
Tgv deletes
1050x
Cobb/aem pump
Killerbee header
Stock airbox

I have tested for boost/vac leaks and exhaust leaks. New front o2.
Fuel Pressure is good it looks like in the logs.
Anybody ever had lean spool or just delayed afr? The car feels strong, does not have any misfire, cylinder roughness or knock.
has he checked your tip in enrichment. if he sayas somethings not right, I would switch your fuel rails back to stock and go from there. I think you changed too many things at once so to figure it out youre probably going to back track
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Old 02-24-2020, 06:00 AM   #5
Subakook
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Quote:
Originally Posted by subaru_gc8 View Post
has he checked your tip in enrichment. if he sayas somethings not right, I would switch your fuel rails back to stock and go from there. I think you changed too many things at once so to figure it out youre probably going to back track
Plenty of folks running this exact setup and haven't seen anyone withsimilar issue.
Thought may be injector issue but no misfires or cylinder roughness.
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Old 02-24-2020, 12:35 PM   #6
Jedi03
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how is your fuel pressure?
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Old 02-24-2020, 12:43 PM   #7
Subakook
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Good I think. It reads in the logs under fuel pressure raw.
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Old 02-25-2020, 08:52 AM   #8
BurninSTI
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I assume the condition is happening at full throttle? Why has he not touched the open loop maps? I mean it doesn't seem too hard of a fix to drop the commanded lambda down a few points in those areas, should be as simple as logging and adjusting the wonky ranges to give you the afr you are looking for. I just did this myself.
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Old 02-25-2020, 12:30 PM   #9
awfulwaffle
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I've seen nasty fuel pressure pulsation lower in the RPM range cause a leanout firsthand. The factory ECU doesn't read data quick enough to see it entirely, though your current pressure trace would possibly look rough in that range. I ended up getting a dedicated high rate scope to watch the fuel pressure sensor directly when I dealt with the issue. May be worth a check.
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Old 02-25-2020, 03:01 PM   #10
subaru_gc8
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Quote:
Originally Posted by Subakook View Post
Plenty of folks running this exact setup and haven't seen anyone withsimilar issue.
Thought may be injector issue but no misfires or cylinder roughness.
you know did hear from the shop that I sent my car to that they had a problem with that fuel pump and the stock fpr, that cold be part of the problem.. jsut because you dont hear of the problem doesnt mean other havent had it..just saying
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Old 02-25-2020, 07:20 PM   #11
Subakook
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DGM

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I think I did the first two pulls a little abrutly. I'm not so sure there is really a problem now. As far as the tuner is concerned. He just has me tripping out about leaks and such. He is cautious.
I am on another revision right now.

I have the cobb regulator also.
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