Subject	Lean AFR question
Posted by	beanz on May 09, 2012 at 4:43 PM
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Message	I am in the midst of diagnosing a lean AFR situation. I know that there are many things that can go wrong on our cars to cause AFR issues. Instead of getting deep into the history of my issue, at this time I have a specific question. Both times I have been lean on the dyno (two times in a row) the dyno operators have indicated that the steadiness of the AFR readings suggests to them the problem is the program in my ECU. What I'd like to know is if any of you have personal experience with AFR curves that look like mine that were not an ECU issue. Or, if you believe that this definitely looks like an ECU issue. Although one of my next steps might be to try an ECU from a different vendor, I am interested in whether or not your experience with AFR curves like mine says "ECU" as loudly as it does to my dyno shop. I guess I'm just not ready yet to believe the ECU is the problem, which might just be stubborn of me. This run was done with my boost controller disabled. The dotted label reads "12.99". I also have video of a boost gauge next to a fuel pressure gauge from the run above (fuel pressure seems high to me, if anything, based on info in the 6 Ps). Click to play. Thanks. Andy As a post script, to get it out of the way just in case some of you do want to ask more questions: AFR was checked using both a wideband tail pipe sniffer and a wideband in a bung in my exhaust. This was over the course of two dyno sessions (first was the tailpipe sniifer, second was the bung). The results were essentially the same. The tailpipe sniffer recorded the same readings from both sides of the exhaust. The bung is only in the passenger side. I have done a boost leak test. Air is escaping past the half moon plugs on the back of my exhaust valve covers, but I don't think I have issues anywhere else. And I am leaking almost no oil from the exhaust valve covers. This is something I am going to fix, but it doesn't seem like it's my problem. To me. As shown above, fuel pressure seems to be okay. High if anything (~58psi fuel@~7.5psi boost) My current ECU vendor has triple checked my ECU and the program on it and is confident the ECU is fine.
Follow Ups	Lean AFR question - beanz 16:43:53 05/09/12 Because your fuel pressure is fine I would venture to say - treese88 09:50:32 05/10/12 As far as I know, all my injectors are original, less 1... - beanz 10:28:10 05/10/12 FWIW, my injectors seem to ohm out okay from the harness - beanz 13:15:55 05/10/12
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