T O P I C R E V I E W
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asskickn88
Member # 4957
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posted
I'm trying to get my dads 93 BMW 740i to pass smog. It was really close to passing but the NOX was a little too high. I would do cats but universal ones wont fit and replacement ones are like almost $400 each. Thanks in advance for any help!
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blind
Member # 3052
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posted
NOX could be a combination of a few things.
Bad or non-functioning EGR, and running too hot pop to mind first. [ May 24, 2005, 09:20 PM: Message edited by: blind ]
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asskickn88
Member # 4957
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posted
Ill have to check the EGR, I know its not running hot. thanks
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Jimbo
Member # 1456
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posted
Bimmers can be a b@&$h to get thru smog. I dont think it has an EGR valve but certainly check the passages and make sure its operating correctly if it has one. Basically NOx is caused by heat in the combustion chamber, make sure the cooling system is in tip top shape, make sure its not running lean(change the fuel filter if its old), make sure the O2 sensor is switching properly, if your not already running 91 octane put in 91. Bring it in nice and warmed up but maybe on a cool morning. You can even request that the tech put the cooling fan on the front of the car, by law they HAVE to have it on when the temp outside is over 72 deg. but there is nothing that say you cant have it on under 72. Hope all this helps but sometimes on those Bimmers the only thing to do is replace the cats. [ May 26, 2005, 08:04 AM: Message edited by: Jimbo ]
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