Air/fuel Ratio

dperez · 03-03-2009, 05:45 PM

I took my car to the dyno (135i with JB3, Riss Raicing Exhaust) and the A/F ratio start at 14.1 and slowly went down 11.8. Is ok or is lean?

Dave · 03-03-2009, 05:50 PM

sounds a bit lean

how many runs and up to what gear 4th or 5th?

Monaco35Dream · 03-03-2009, 05:54 PM

How about octane? and which map(s) were used?

drumnatural · 03-03-2009, 06:23 PM

11.8 may be ok depending on how much boost your running at the time. 14.1 isn't to far from stoich but as soon as you go WOT it should switch to the open loop map which is richer.

What A/F ratios at what boost level when the car is stock really needs to acertained before you can really know for sure though.

I'm coming from Honda/Acura tuning so somebody let me know if BMW has more then just a close loop map and then open loop map.

rcracer_tx · 03-03-2009, 08:09 PM

Direct injection engines run leaner than traditional fuel injected engines... Looks good to me, but email terry if you are concerned

E82tt6 · 03-03-2009, 09:52 PM

Sounds normal. All my dynos have run lean in the low end, then richened up. 12:1 sounds about perfect for street fuel IMHO.

mkPOTO · 03-04-2009, 12:37 AM

Quote:

Originally Posted by rcracer_tx

Direct injection engines run leaner than traditional fuel injected engines... Looks good to me, but email terry if you are concerned

bingo

mixxer · 03-04-2009, 07:25 AM

It depends how your reading A/F is it thru an exhaust bung or tailpipe sniffer?And anyone who didnt ask that before they gave their 2 cents doesnt should not have answered!

dperez · 03-04-2009, 07:21 PM

The car was on map 3 (boost 12 to 14 psi), 93 octane and the run was on 3th.

03-03-2009, 05:45 PM	#1
dperez New Member 5 Rep 28 Posts Drives: 135i white Join Date: Mar 2009 Location: puerto rico iTrader: (0)	Air/fuel Ratio I took my car to the dyno (135i with JB3, Riss Raicing Exhaust) and the A/F ratio start at 14.1 and slowly went down 11.8. Is ok or is lean?
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03-03-2009, 05:50 PM	#2
Dave formerly izzo/comeback 287 Rep 3,382 Posts Drives: 2016 RC 350 F Sport Join Date: Dec 2007 Location: NJ iTrader: (3) Garage List 2008 135i [6.80]	sounds a bit lean how many runs and up to what gear 4th or 5th?
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03-03-2009, 05:54 PM	#3
Monaco35Dream Captain 44 Rep 647 Posts Drives: 08' 135i, 96' Talon Tsi AWD Join Date: May 2008 Location: Santa Maria, CA iTrader: (1) Garage List 2008 135i [0.00]	How about octane? and which map(s) were used?
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03-03-2009, 06:23 PM	#4
drumnatural New Member 0 Rep 18 Posts Drives: 135i future owner Join Date: Mar 2009 Location: Maryland iTrader: (0)	11.8 may be ok depending on how much boost your running at the time. 14.1 isn't to far from stoich but as soon as you go WOT it should switch to the open loop map which is richer. What A/F ratios at what boost level when the car is stock really needs to acertained before you can really know for sure though. I'm coming from Honda/Acura tuning so somebody let me know if BMW has more then just a close loop map and then open loop map.
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03-03-2009, 08:09 PM	#5
rcracer_tx Banned 55 Rep 2,013 Posts Drives: BSM 135i Join Date: Apr 2008 Location: Texas iTrader: (0)	Direct injection engines run leaner than traditional fuel injected engines... Looks good to me, but email terry if you are concerned
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03-03-2009, 09:52 PM	#6
E82tt6 Colonel 103 Rep 2,626 Posts Drives: '08 Black Saphire Z4 MC Join Date: Oct 2007 Location: New Jersey iTrader: (0)	Sounds normal. All my dynos have run lean in the low end, then richened up. 12:1 sounds about perfect for street fuel IMHO. __________________ '08 Black Saphire/Black Z4 M Coupe RIP Gretta: Blue Water/Lemon 135i. Died to save me. -ChuckV
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03-04-2009, 07:25 AM	#8
mixxer Second Lieutenant 3 Rep 226 Posts Drives: 2010 335 xi Join Date: Mar 2009 Location: phoenixville,PA iTrader: (0)	It depends how your reading A/F is it thru an exhaust bung or tailpipe sniffer?And anyone who didnt ask that before they gave their 2 cents doesnt should not have answered!
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03-04-2009, 07:21 PM	#9
dperez New Member 5 Rep 28 Posts Drives: 135i white Join Date: Mar 2009 Location: puerto rico iTrader: (0)	The car was on map 3 (boost 12 to 14 psi), 93 octane and the run was on 3th.
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