QuestionQUESTION: I have a 1992 F150 extended cab with a 5.0 302 v8 engion... when I first bought it (like 6 months ago) it was getting 9 mpg, and I put on an 02 censor and gave me 18 mpg after that for about 2 weeks.. after the initial two weeks, the truck was still running great, no bad idling or anything, but then the mileage went back to 12mpg. My truck couldn't be scanned to see if the O2 censor got burnt out, but we did check it with... a voltmeter or something like that and that indicated that it was still working, but then I was getting 12 mpg... So then I did a tune up on the ole ford and now I'm running about 14 mpg.. any ideas on why a small v8 would get such horrible fuel economy? Any ideas are appreciated!
ANSWER: Hey there Brad, You may have a fouled up O2 sensor again if you were running bad still after putting the sensor in then later did the tune up that could be your problem. You may also want to check your ignition timing and see if it is to spec. Just because the O2 sensor was switching does not mean it is switching fast enough or with the right amount of voltage. As well you might want to check your catalytic converter and make sure it is not restricted. If you have restricted exhaust you may not have a derivability concern but will be consuming more fuel because you need to use more foot feed for driving which uses more fuel. If you have anymore questions please give me a shout.
Regards
Jim
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QUESTION: Alright thanks alot for those tips. Those were actually two of the things I was thinking and I'm glad to hear I wasn't way off base. My truck has actually got 2 catalytic converters and I was thinking about either taking them right off or gutting them out for two different reasons. First reason is for better flow from the engion and the second reason is cuz I'm still young and want my truck to be loud, haha. My main question is; there is a pipe inbetween the catalytic converters that goes from the exhaust to the engion, what does it do? and if I were to take the cats off, what should I do with it?
Oh, I actually am not sure if I am taking them off or not. If I were to do anything to them within the next week or two, it'd just be gutting them out basically so I wouldn't have to run more pipe.
Again, I really appreciate your response, I was amazed at how fast it was before!
-Brad
ANSWER: Hey brad sorry for the long response was a long weekend here in Canada and i spent it with the family. but as for the tube that goes up from the exhaust up to the engine. it is there as a heat riser to help aid in the quicker heating of the engine. I have seen others run with them not operational with no concerns. I hope this helps out a bit for you. once again sorry for the long reply time
Jim
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QUESTION: I have one more question... I know 100% for sure its the o2 sensor now... and I bought one a week ago now and installed it and it went bad after a day... but, I also didn't disconnect the battery to reset the computer. I was told that that would make a difference. so tonight I installed a new one after disconnecting the battery for 20 minutes. If this doesn't work, do you have any idea why I'd be burning them up so quickly? this last sesnor did give me a check engion light. The new one only has 40 miles on it and is running good, but if you have any ideas they'd be appreciated. My only idea would be something in the wiring with the connection or something along those means.
AnswerHi there Brad. Is the sensor fouling up or is it not switching? if the sensor is fouling up is it because of oil contamination or something else. the battery will need to be disconnected to clear the keep alive memory but it really should not damage a sensor that quickly that i have seen. We at the shop here have been provided with faulty new sensors from time to time :S not really liking that but it does happen. how are you testing these O2 sensors and if you are checking them with a scan tool then i would not suspect any wiring problems if the new one works good and you can see a nice changing voltage.
Let me know your outcome
Jim
