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Darn newfangled technology! Posted by Ari [Email] ![]() ![]() In Reply to: Re: Ignition/mixture, Yaofeng, Thu, 13 May 2004 16:14:51 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I'll tell you, this digital stuff is just a passing fad.
Your NOx numbers aren't way out of line. Just far enough for you not to pass. It would be nice if the plugs looked bad, but sometimes we can't be that lucky (!?!)
Nevertheless, I'm going to assume that you're running on the lean side. Maybe not wickedly lean, but still lean enough to spike the NOx. Yeah, it could be the catalytic converter, but let's think happy thoughts for now.
I'd still go for a set of new plugs. Maybe go to one cooler heat range. Next, look for vacuum leaks. They probably won't be huge, but every little bit counts.
It would be great if you could stick a voltmeter on the O2 sensor output. See what it thinks. The voltage should be swinging back and forth around 0.5 volts. If the sensor thinks the engine is lean (more time less than 0.5 volts), then it's a vacuum leak, or maybe the fuel pressure is a little low. If the sensor thinks the engine is rich, then it could be the sensor - it's telling the ECU the engine is rich, so the ECU leans the mixture out. One crude way to test the O2 sensor - At idle, pull any vacuum line other than the one to the FPR off and leave it open - the O2 sensor output should go to lean. Replace hose. Now, pull the vacuum line from the throttle body to FPR off and plug it - the sensor output should go to rich.
That's a crude test. Where you might have a problem is a 'lazy' O2 sensor - namely, it responds, but slowly. This happens to some sensors as they age. Unfortunately, I don't know of a quick and dirty way to test that.
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