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Emissions and Air-Fuel-Ratio data logs 2010/08/07

Posted by Michael in 2JZduino.
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I realize it’s been more than a month since my last post, in most part because progress has been slow.

I had some exhaust work done to improve airflow in preparation for the Supercharger. This involved replacing the stock exhaust manifold with an after-market long-runner header. The OE exhaust manifold includes two primary catalytic converters, so in addition to the installation of the new header I had a local shop also install a high-flow catalytic converter: the Vibrant Performance (p/n 7001) ceramic core high-flow. I had the car tested for emissions both before and after the exhaust work. Results below…

Vehicle: 2004 IS300
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“Before” Configuration: Lexus stock setup for all engine and exhaust except SRT intake with piggyback ECU
Test preparation: 20 minute commute to the E-Test shop at highway speeds
Date: July 21 2010 @ ~8am

ASM2525 Test readings (limit) _ RESULT: @ 2650 RPM
– HC ppm 6 (58) _ PASS
– CO% 0.00 (0.32) _ PASS
– NO ppm 0 (435) _ PASS

Curb Idle Test readings (limit) _ RESULT: @ 800 RPM
– HC ppm 5 (150) _ PASS
– CO% 0.00 (0.70) _ PASS

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“After” Configuration: Megan racing exhaust manifold, Vibrant Performance (p/n 7001) high-flow ceramic core cat installed ~6″ downstream of y-pipe/header connection (custom flange and merge collector on the y-pipe, two O2 bungs post-cat, welded to stock mid-pipe).
Test preparation: 20 minute commute to the E-Test shop at highway speeds
Date: July 30 2010 @ ~8am

ASM2525 Test readings (limit) _ RESULT: @ 2700 RPM
– HC ppm 17 (58) _ PASS
– CO% 0.04 (0.32) _ PASS
– NO ppm 64 (435) _ PASS

Curb Idle Test readings (limit) _ RESULT: @ 830 RPM
– HC ppm 17 (150) _ PASS
– CO% 0.01 (0.70) _ PASS
– NO 75 (N/A) _ N/A

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I also had an extra bung welded into the the Megan header and have installed a wideband oxygen sensor: the Innovate Motorsports LC-1. I’ve been monitoring air-fuel-ratios for the past 2 weeks while going about my normal driving. As expected the vehicle operates at 14.7:1 under closed loop. Below I’ve posted data collected through 2JZduino during a full-throttle pull in 2nd gear right up to the throttle limiter to observe the fuel mixture of the stock ECU in open-loop (pardon the slow data rate… code was a bit of a hack).

This log begins at part throttle rolling in 2nd gear at ~700 rpm. The MAP climbing to 100 KPa (1 atmosphere) identifies the throttle going wide open. At ~6400 RPM the stock ECU closes the throttle to limit engine RPM. Note the stock ECU seems to maintain quite a rich mixture throughout all RPMs, never going above 12.5:1 and reaching as low as 10.7:1 at 5000 RPM.

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