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Discussion Starter · #1 · (Edited)
Hi guys I'm trying to figure out why specifically at 3000-4000. my afrs are 12.1-12.5. 2500 its around 12.5 and tapers immediately to 11.9 before that range, but all the time it spikes back up and as soon as it passes 4000 it'll go back to its normal 11.7 to 11.5 to 11.3 by redline. I have the stock jdm mivec map. I'm pushing 23psi. I adjusted the afr maps and its wonky looking I didn't have this issue before.... Lean spool is off. I'm straight piped to the oem downpipe, stock turbo, stock manifold with grimmspeed ebcs and vta catch can setup by MAPerformance. I'm not knocking at all. My boost curve is pretty good.

Could a exhaust leak DOWNSTREAM of the turbo exhaust to wideband sensor(test pipe flange to downpipe) cause a lean spike, I never had this issue before and why? It wouldn't make sense to me because the exhaust pipe is under positive pressure so if anything air would be escaping at that point.
 

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Discussion Starter · #2 ·
Changed my MAF as I had a spare one kicking around and my car stopped sputtering on throttle let off and decel but I noticed the afr under wot is lean if not leaner than before
 
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