does taking cats off give you worse gas mileage?
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does taking cats off give you worse gas mileage?
i have a sc400 1992 with 190k miles. the previous owner has gutted both the cats and i get pretty bad gas mileage.like 10 mpg in city and 18 highway.my question is would i get better gas mileage if i put back catalytic converters?im thinking about magnaflow cats which cost around 70$.u guys think this is a good idea?
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so cats dont have anything to do with gas mileage?my mechanic said it would improve..i was planning to change my o2 sensors and is there any way you can tell if o2 sensors are bad by looking at them?when i took them out they looked pretty good(almost no carbon but i used a blow torch to heat them up) i kinda felt a difference but could be my mind.
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actually it will...
the SC400 comes with 4 o2 sensors, 2 before and 2 after the main cats. If you hollow out the cats, the secondary sensors will think that you are running rich and will adjust. That is probably why you're having this problem now.
the SC400 comes with 4 o2 sensors, 2 before and 2 after the main cats. If you hollow out the cats, the secondary sensors will think that you are running rich and will adjust. That is probably why you're having this problem now.
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Lean fuel mixture does affect little bit but not dramatically.
It will not go too lean where it may hurt the engine.
Lean= higher operating temp in combustion chamber.
Long term fuel trim will go lean. Short term will run rich at times. So not that dramatic. If you are getting 10 mpg fix cat. I will start from there. Fyi (Non forced induction cars need back pressure from exhaust system to run more efficiently. Called scavenging using back pressure, helps to suck out exhaust gas from other combustion chambers)
That means, if you change the amount of back pressure by length of headers or larger pipes they all may affect it.
Either gain power to loose mpg. Or gain mpg to loose power.
Going back to bad mpg, lot of variables but fix that fuel mixture. Then drive it to see its gotten better.
If not, time to look more in depth. Cooling temp, air mass sensor,fuel pump efficiency fuel volume delivery, filters , injectors ect.
Probably I'm forgetting something but just a rough idea.
Plus, keep in mind that preventive service is a good way to keep your cars runnIng healthy.
It will not go too lean where it may hurt the engine.
Lean= higher operating temp in combustion chamber.
Long term fuel trim will go lean. Short term will run rich at times. So not that dramatic. If you are getting 10 mpg fix cat. I will start from there. Fyi (Non forced induction cars need back pressure from exhaust system to run more efficiently. Called scavenging using back pressure, helps to suck out exhaust gas from other combustion chambers)
That means, if you change the amount of back pressure by length of headers or larger pipes they all may affect it.
Either gain power to loose mpg. Or gain mpg to loose power.
Going back to bad mpg, lot of variables but fix that fuel mixture. Then drive it to see its gotten better.
If not, time to look more in depth. Cooling temp, air mass sensor,fuel pump efficiency fuel volume delivery, filters , injectors ect.
Probably I'm forgetting something but just a rough idea.
Plus, keep in mind that preventive service is a good way to keep your cars runnIng healthy.
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so cats dont have anything to do with gas mileage?my mechanic said it would improve..i was planning to change my o2 sensors and is there any way you can tell if o2 sensors are bad by looking at them?when i took them out they looked pretty good(almost no carbon but i used a blow torch to heat them up) i kinda felt a difference but could be my mind.
Quest. Why were you about to change o2 sensor when your car is hollow??
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[QUOTE=xspsi6;7301237]Obd 1 systems can not have that much control over air/fuel mixture as it is usually in the +/- 7% correction so the lack of cats are not your problem, Look else where such as a bad coolant temp sensor etc.[/QUOTE
where can i find the coolant temp sensor and how does it affect my gas mileage?sorry im a little new on this topic..
where can i find the coolant temp sensor and how does it affect my gas mileage?sorry im a little new on this topic..