Catyalitic converter
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Catyalitic converter
Does a 1998 f150 really have 4 cats? I have a hesitation under a load at all speeds and the rotten egg smell ive been told is related to a bad cat. if there are multiple how can i tell which is bad?
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From: Hernando Ms
Actually...yes..
.well sort of.You have 2 "pre cats" and two normal cats.
The rotten egg smell doesent necessarily mean you have a bad cat. You have 4 02 sensors,one upstream of each main converter,and one downstream.The upstream 02 sensors control the computer,the downstream ones merely tell the computer if the cats are doin their job.
If you arent getting a cat CEL code,I suspect the main ones are fine.The "pre-cats" are much smaller,and I would think if one of them were bad,you would still get a CEL code.
I remember someone telling me WAY back in the past that the rotten egg smell is normal,and not an indication of a bad cat.This may be an old wives tale....
.well sort of.You have 2 "pre cats" and two normal cats.The rotten egg smell doesent necessarily mean you have a bad cat. You have 4 02 sensors,one upstream of each main converter,and one downstream.The upstream 02 sensors control the computer,the downstream ones merely tell the computer if the cats are doin their job.
If you arent getting a cat CEL code,I suspect the main ones are fine.The "pre-cats" are much smaller,and I would think if one of them were bad,you would still get a CEL code.
I remember someone telling me WAY back in the past that the rotten egg smell is normal,and not an indication of a bad cat.This may be an old wives tale....
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Ok thanks i also read sum things on this site that may be leading me to a bad coil maybe. can i take it to a shop and have them test them so i can replace the bad one my self? by the way its a 1998 f150 5.4 with 230,000 miles on her and never had 2 change a coil yet think they go bad over time or sumthin else wrong? And i havent got a check engine light yet on this issue
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Yeah, if you don't have a cat code, look elsewhere for now. The cat should never fail unless something else goes wrong first.
Hesitation under load often indicates either a misfire or a bad fuel to air ratio. I would replace O2 sensors and clean the MAF, and check the LTFT on both banks with a scan tool.
Hesitation under load often indicates either a misfire or a bad fuel to air ratio. I would replace O2 sensors and clean the MAF, and check the LTFT on both banks with a scan tool.
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LTFT is the Long Term Fuel Trim. Basically, the computer has a built in fuel table that tells how much fuel the engine requires under various load conditions. If it has to make and adjustment, the adjustment amount is logged as a fuel trim. It has a Sort Term Fuel Trim, which is how much it is adding or subtracting right now, but it also has a LTFT, which is an average of how much it adds or subtracts from the built in values over an extended time period. Vehicles that are properly tuned will have LTFT values very close to zero percent. If the values are consistently more than 3% high or low, it indicates that something is wrong, though it may not be wrong enough to set a code for it. If it goes beyond 5%, something is definitely wrong, and if left unchecked, converter damage will eventually occur.
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Ok thanks do i need to buy a real expensive scanner or will one for 100 bucks from checker do what you suggest? thanks for the help
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You need a scanner, not a code reader. Just so long as the tool you get allows you to read live data it will work, if it only allows code retrieval and freeze frame its not good enough.
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