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Re: Smock Check Fail Q's Posted by Ari [Email] ![]() ![]() In Reply to: Smock Check Fail Q's, Aaron, Wed, 13 Nov 2002 13:51:55 Members do not see ads below this line. - Help Keep This Site Online - Signup |
As JimBlake says, high NOx is usually due to high combustion temps. This is usually due to a lean mixture. Yes, a bad O2 sensor can cause a lean mixture. But O2 sensors basically have two failure modes - either they get very slow in their response, or they quit outright. If it quits outright, the engine will default to a richer mixture, which would give you a hydrocarbon/CO issue, not NOx.
My guess is either a vacuum leak or a mis-adjusted AMM. A vacuum leak will cause you to run lean. The O2 sensor controls 25% of the fuel flow; the AMM controls 100%. If the AMM is misadjusted, you could be running lean.
Check how to adjust the AMM - there have been a few posts on it. Clean up all your vacuum leaks first, then check the adjustment of the AMM, and readjust as necessary.
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