What AFRs Are You Getting?
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Joined: Oct 2011
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From: dfw
if your on aem v1 o2 feedback needs to be on i have seen few tuners use it due to map problems but if you limit the feedback to 20% it seems to be stable my car would run lean after hot starting 16.5-17 some hesitation o2 feedback fixed it
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Joined: Feb 2013
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From: Texas
I'm at around 13.2 under load, 14 while cruising or idle. I only see 16 and above when I let off the pedal, if you're seeing those numbers just cruising you're running lean probably need to get your tune checked. Is your sensor in good shape? My OEM sensor and AEM wideband sensor give different readings. I'll need to replace my OEM sensor here soon.
I paid more attention to my AFR's while driving today. Everything looks spot on minus when I'm like 5%-10% on the throttle just maintaining speed, that's when I'm consistently in the 16s.
I called my tuner and talked to him; He said he left it that way intentionally as he wanted to try to help gas mileage but could lower it if I'd like. I'm going to get it tuned down to at least mid 14's this Friday.
I think the 3K-4K stutter could be something else; I'll also look at that coming up. All in all though, the car is running pretty good. Just ironing out some small issues
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14.7/stoich should be the idle/cruising target, up to 15.5, leaner then that and the engine will typically start to starve for fuel and you will not only run hotter but get worse MPG because the engine is having to work harder to maintain speed. Anything richer then 14.5 and your just wasting gas in this running. It should richen up to 13.5-13.8 afr in the 20-30% transitional throttle between cruise and WOT tune however. It shouldn’t just go from 14.7 to 11.8 WOT. Unless the tuner didn’t take the time to maximize the fuel tuning the engine wants.
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From: Texas
Joined: Dec 2009
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From: Santa Clartia, Ca
Lots of newer cars run really lean while idling for MPG and emission purposes. Still your car is running pretty excessive IMO. 14s is where you need to be at when cruising. I would imagine at 15/16 the car would feel like the engine is hiccuping and stuttering as its trying to get more fuel.