Sunfiretun3r wrote:P0420 is catalyst efficiency code, so yes that will affect your mpg's. I believe that code will put the car in open loop all the time, but I could be wrong about that. I know if the o2 before the cat has a problem that will go into open loop, but I'm not sure about the post cat o2. Been awhile since I've had theory in my head.
As for the mpg's with 89 vs 87, with the results posted in this thread, I might have to give it a shot.
HardcoreXSunfire wrote:Sunfiretun3r wrote:P0420 is catalyst efficiency code, so yes that will affect your mpg's. I believe that code will put the car in open loop all the time, but I could be wrong about that. I know if the o2 before the cat has a problem that will go into open loop, but I'm not sure about the post cat o2. Been awhile since I've had theory in my head.
As for the mpg's with 89 vs 87, with the results posted in this thread, I might have to give it a shot.
i asked awhile back in a different thread and never got an answer but what causes the p0420 code?
Sunfiretun3r wrote:HardcoreXSunfire wrote:Sunfiretun3r wrote:P0420 is catalyst efficiency code, so yes that will affect your mpg's. I believe that code will put the car in open loop all the time, but I could be wrong about that. I know if the o2 before the cat has a problem that will go into open loop, but I'm not sure about the post cat o2. Been awhile since I've had theory in my head.
As for the mpg's with 89 vs 87, with the results posted in this thread, I might have to give it a shot.
i asked awhile back in a different thread and never got an answer but what causes the p0420 code?
A bad cat. Honestly. It means that the cat isn't doing it's job, and the o2 sensor isn't seeing enough oxygen or is seeing too much oxygen in the post cat exhaust gases. The materials inside the cat do get "loaded up" I guess you say. They stop working like they originally did. Cat's can also get clogged from excess fuel. And excess fuel can cause the catalyst to burn up and literally melt. Most of the time though it's just caused from the cat being old and not functioning properly anymore.
Do you have a high flow cat? High flows (especially magnaflow) go bad rather quickly. Not sur eon the reasons why, but they cause a P0420.
HardcoreXSunfire wrote:Sunfiretun3r wrote:HardcoreXSunfire wrote:Sunfiretun3r wrote:P0420 is catalyst efficiency code, so yes that will affect your mpg's. I believe that code will put the car in open loop all the time, but I could be wrong about that. I know if the o2 before the cat has a problem that will go into open loop, but I'm not sure about the post cat o2. Been awhile since I've had theory in my head.
As for the mpg's with 89 vs 87, with the results posted in this thread, I might have to give it a shot.
i asked awhile back in a different thread and never got an answer but what causes the p0420 code?
A bad cat. Honestly. It means that the cat isn't doing it's job, and the o2 sensor isn't seeing enough oxygen or is seeing too much oxygen in the post cat exhaust gases. The materials inside the cat do get "loaded up" I guess you say. They stop working like they originally did. Cat's can also get clogged from excess fuel. And excess fuel can cause the catalyst to burn up and literally melt. Most of the time though it's just caused from the cat being old and not functioning properly anymore.
Do you have a high flow cat? High flows (especially magnaflow) go bad rather quickly. Not sur eon the reasons why, but they cause a P0420.
Thank you for the explanation. No I dont have a high flow. Its the factory cat, im assuming never replaced since it rolled off the assembly line in 1997.
95LsCoupe wrote:kind of off the gas mileage topic, but does high octane burn hotter? a long time ago someone told me it does, now a turbo guy is telling me it burns colder(which i think is stupid because more heat, more expanding) and google just told me they all burn the same....just wana clear it up
HardcoreXSunfire wrote:95LsCoupe wrote:kind of off the gas mileage topic, but does high octane burn hotter? a long time ago someone told me it does, now a turbo guy is telling me it burns colder(which i think is stupid because more heat, more expanding) and google just told me they all burn the same....just wana clear it up
if you opened your eyes and read this thread you would have your answer
95LsCoupe wrote:kind of off the gas mileage topic, but does high octane burn hotter? a long time ago someone told me it does, now a turbo guy is telling me it burns colder(which i think is stupid because more heat, more expanding) and google just told me they all burn the same....just wana clear it up