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Re: 85 900T failed emissions on NOX...help???!!!!!... Posted by Justin VanAbrahams [Email] (#32) [Profile/Gallery] (more from Justin VanAbrahams) on Mon, 23 Oct 2000 14:16:11 In Reply to: 85 900T failed emissions on NOX...help???!!!!!..., Pete [Profile/Gallery] , Mon, 23 Oct 2000 12:30:13 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I think we need an FAQ entry for this subject...
High NOx emissions are usually caused by excessive in-cylinder temperatures. On "normal" cars this is controlled by an EGR system, where some portion of the exhaust gases are recycled through the engine to be re-burned and help cool down the cylinder. Unfortunately, 99% of Saabs out there don't have an EGR system. Oopsie!
Most Saabs use exclusively a 3-way catalytic converter to control NOx emissions, meaning the engine has to be in very good tune and the catalytic converter has to be in good working order.
Unfortunately, that means you really gotta be sure the fuel injection and cooling system are working well. Check timing, O2 sensor, AMM, injectors (leaky injectors can contribute to high NOx numbers), even spark plugs and wires. If all of this stuff is in good shape, then try the cat. Of course, if you've still got the original cat, now might be a reasonable time to replace it.
-Justin
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