# 1997 240sx running rich!!!



## Bronx240sx (Sep 24, 2004)

Hey Guys,

I need help. My 97 240sx (auto) is running way too rich! It just spits out black carbon out of the exhaust. I did a smog pre-test and the CO2 measured at 15mph was 6.97 and at 25mph it's over 7.00. So far I've replaced the EGR valve but still no luck. There are no codes and no pending codes. Some people have suggested changing my O2 sensor since I have 109,000 miles, but I'm not sure that's the problem......any ideas would be greatly appreciated. Thanks.........


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## mille-16i (Jun 16, 2004)

running rich can be the result of many things however the most common ones are these 1 the 02 sensor should be replaced every tune up 2 the coolant temp sensor it to should be replaced at each tune ( not the one for the temp gauge the one for the computer) mas air flow sensor could be bad not as likely however. check your air filter you should be able to see light through it when you hold it up to normal light ( flourecent lighting or sun light not your 100 watt driving lights) if non of that is it check you fuel pressure if it is to high then you will get more fuel then the ecu knows.


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## Murph (Aug 8, 2002)

I will put my money on a bad fuel pressure regulator!


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## Nycist (Sep 16, 2004)

with a motor with that many miles there can be a variety of problems. might be your ignition coil arent pushing enough current to ignite ur mixture too well.
maybe a worn belt(over 100k, you should really get that checked) thats making your timing a lil off. these are my best bets.


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