running lean
11-29-2010, 09:42 PM
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running lean I've seen alot of talk about running lean and I was curious as to how you would know if you are running lean or not because I have a cai on my 05 gxp with a stock tune as well as an exhaust. So yeah I'm just a little bit confused
11-30-2010, 02:44 PM
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Your CAI will throw off your MAF tune because it alters the way the sensor "sees" the air. For those who do not already know, the MAF is one of the main components in determining fuel predictions. Initially your car will run lean until the computer learns to add fuel based on your O2 sensors feedback. However, the computer isn't the best at making corrections when the MAF calibration is too far out of whack. I.E. while tuning a members car I had to add 20% more fuel, the computer was only adding about 10% leaving the engine 10% lean at WOT, which if your target a/f ratio is 13.0:1 your actually seeing 14.3 at WOT which leads to KR and power loss. I hope this answers your question.
11-30-2010, 05:28 PM
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Tool in-hand, you would then look at various parameters, such as O2 sensor voltage, long and short-term fuel trim levels, knock retard, etc.
Of course, you'd need to have an understanding of what the various data means. If you decide to obtain a tool, there are plenty of folks on this site who can assist with interpreting the results.
