Since I had it the truck has been running rich?

2002 FORD F-150
54,000 MILES • V8 • 2WD • AUTOMATIC
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HAMMER_JACK
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Hi, and thx for having the time to ask my question. I have a 02' Lighting that I bought used. Since I had it the truck has been running rich. I know for a fact that it has a after market exhust and that one of the pulleys on the belt has been change. Also I replace the air filter to a BBK cold air system. I took the truck to several shops and there saying that the O2 sesors are reading rich, banks 1 & 4. I was going to buy a flash tuner to change the PCM and get rid of the check engine light off but would that fix the problem? I need to fix this because I have to take my baby back to inspection by June. THX
Apr 1, 2008 at 3:07 PM
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BLACKOP555
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you should switch the bank 1 and two sensors and swap them, if the code goes with the o2 sensor then the sensor is bad, if not its engine related. check to make sure the injectors are not leaking or the fuel pressure regulator is bad. also check the MAF sensor.
Jun 28, 2021 at 11:09 AM
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FLEXY5
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I'm not too familiar with the BBK filter set-up. If it is anything like the K&N filters that require being treated with oil, then I would suspect the MAF sensor. The other thing you mentioned that I have seen before is the modified exhaust system. If you have modified cat converters or no cat converters at all, then the downstream O2 sensors are not sending the signal that the computer is expecting. This can cause a rich condition on the upstream O2 sensors. Find out what they have done to the exhaust and if there are even any downstream O2 sensors. I've even seen installers use a shunt and leave out the O2 all together. All this info will help us determine what's going on. Blackop555 is correct, though, check the obvious first and then consider the obscure.
Jun 28, 2021 at 11:09 AM
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BLACKOP555
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leaving the 02 sensors are a problem all too common when using after market exhaust. but id be checking the MAF sensor first, since aftermarket air intakes are known for this.
Jun 28, 2021 at 11:09 AM