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Air/fuel confirmation?

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Old Aug 27, 2011 | 05:46 PM
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Default Air/fuel confirmation?

Hey everyone, just making a post to see if my afr is ok, as im just a bit worried about it.
The car is a lt1 with a d1 procharger, and is running in openloop (i think?) at the moment, as one of my o2 sensors is shot.
When im sitting idling, the car usually sits at about 14.5-16 back and forth, on an AEM wideband. It fluctuates quite a bit and sometimes shoots up to about 17 if the idle goes wonky (not sure why it does that either, sometimes rpms drop way low and it revs itself back up). When cruising it seems to be in a nice 13.5-14.5 and under foot it drops down nice and low to about 11-12. Just making sure this isnt terrible, never owned a FI car before and dont want it to be spitting guts anytime soon.

Also if anyone knows a good place to buy GM erplacement AC delco o2's thatd be great!
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Old Aug 27, 2011 | 08:14 PM
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seems like most of the afr's ive seen in the FI section are right around </=11.5-.7. that 13.5-14.5 when cruising woud personally make me nervous. the 14.5 seems to be about right at idle from what ive read. Im no expert, just sharing what i have read. im sure someone else wll chime in.
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Old Aug 27, 2011 | 08:24 PM
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Originally Posted by allout06
seems like most of the afr's ive seen in the FI section are right around </=11.5-.7. that 13.5-14.5 when cruising woud personally make me nervous. the 14.5 seems to be about right at idle from what ive read. Im no expert, just sharing what i have read. im sure someone else wll chime in.
Mine is 14-14.7 when cruising that's what it is really supposed to be for optimal fuel economy and emmissions. As soon as I get into about -10 vaccum my AFR Will gradually go from 14ish to low 13s high 12's then once it's at 0 vaccum transferring to boost it's in the high 11's, once I hit full boost it's at 11.1-11.3. From there it will hold till pk. tq. at 4500-5000rpm then slowly lean out from 11.3 to 11.7-11.8 where I shift at 6500-6600rpm.
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Old Aug 27, 2011 | 08:32 PM
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Ok so mines not to far off.
Also, and this is probably stupid, but when rolling downhill in third or fourth, so they car is making...backpressure? like the speed of the engine is slowing down the car, or holding it back from accelerating, my afr peaks out, and dashes out the gauge. Is that expected? It kind of makes sense, low gas being delivered to engine while its flowing air, just making sure thats nothing redic?
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Old Aug 28, 2011 | 04:27 AM
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But if you were in boost and ur afr was around the same as it is at 0 vacuum. That'd be pretty lean right?
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Old Aug 29, 2011 | 01:45 AM
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not if it's not lean at 0 vacuum...

What i posted isn't accurate down to the minute point as the sweep on my afr gauge isn't really easy to follow while I am at full throttle trying to watch the road and gauge. At the strip I can easily watch the gauge, but not on the street where load conditions, tip in, and a lot of other variables come into play.
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