I posted this thread some months back, complaining about how installing high flow cats had robbed my car of some power. It was surprising, given that the high flow cats I installed uses metallic cores, which flow extremely well; almost as well as catless
Anyway, the past few months have been aggravating to say the least. At first, I thought I could live with the dip in performance....but I began to also notice that my fuel economy was noticeably worse.
If I had to guess, I'd say my fuel economy had dropped by 2 mpg. I sucked this up though, and put it down as just another symptom of being catted.
But then 2 weeks ago, I noticed that my fuel economy had dropped by 5 mpg, which I could no longer ignore. Something was up, but my car hadn't given me any codes or errors.....until 6 days ago.
The code I got was P0133:
Oxygen Sensor Circuit Slow Response (Bank1, Sensor1)
I read the code with my diablosport predator tuner, looked it up online and found that it's likely caused by a malfunctioning upstream o2 sensor on the driver's side....or a leak in the exhaust.
I knew I didn't have a leak, so I bought 2 new upstream o2 sensors from autozone and had my mechanic install them. Even though P0133 refers specifically to the driver side o2 sensor, I bought a second one for the hell of it to install in bank 2.
Turned on the car, deleted the code with the tuner, and drove it off.
Immediately, I felt a difference in the car in terms of not only how it felt, but how it sounded. Got it out on the highway, and I couldn't believe how much more powerful it was! Felt as though I had gained 20 hp
As a matter of fact, the car felt more powerful than it did when I was catless!
Drove it to work today and on the way back, I also noticed another pleasant surprise.
The speed limit on highway 288 is 65 mph. At 65, my car would always be exactly at 2,000 rpm.....now it's under 2,000 rpm by a few ticks.
So apparently, changing the upstream o2 sensors has not only made my car more powerful, it has made it more efficient as well....which means more money saved at the gas station. :thumbsup:
So the moral of the story is, make sure you change your upstream o2 sensors every so often, because they can impact performance and efficiency in a big way since they help the ECU adjust the A/F mixture.
One thing I can't figure out though, is why I had such a big performance decrease the first time after installing the high flow mids
Obviously, it wasn't the high flow mids that was causing the performance loss, but I can't recall the car feeling like it had lost any power whatsoever when I was catless, and the only error code that I had at the time referred to the downstream o2 sensors due to having no cats.
Perhaps being catless was hiding the performance and inefficiency issues caused by the faulty o2 sensor, then after installing the high flow cats, the issues became noticeable?
Since my car has a large engine and is modded, being catless is good for an extra 10 hp to 15 hp easily. Removing the cats would have forced the ECU to readjust the A/F ratio, which takes a few days usually. But if the o2 sensor was faulty, it would not have been able to properly calculate the new A/F ratio for the high flow cats, which explains why the car felt so weak after they were installed....especially after I drove it from my mechanic's shop.
Anyway, how often should the o2 sensors be changed? I'd assume they'd wear out faster on a modified vehicle, due to the faster, hotter exhaust stream?
Anyway, the past few months have been aggravating to say the least. At first, I thought I could live with the dip in performance....but I began to also notice that my fuel economy was noticeably worse.
If I had to guess, I'd say my fuel economy had dropped by 2 mpg. I sucked this up though, and put it down as just another symptom of being catted.
But then 2 weeks ago, I noticed that my fuel economy had dropped by 5 mpg, which I could no longer ignore. Something was up, but my car hadn't given me any codes or errors.....until 6 days ago.
The code I got was P0133:
Oxygen Sensor Circuit Slow Response (Bank1, Sensor1)
I read the code with my diablosport predator tuner, looked it up online and found that it's likely caused by a malfunctioning upstream o2 sensor on the driver's side....or a leak in the exhaust.
I knew I didn't have a leak, so I bought 2 new upstream o2 sensors from autozone and had my mechanic install them. Even though P0133 refers specifically to the driver side o2 sensor, I bought a second one for the hell of it to install in bank 2.
Turned on the car, deleted the code with the tuner, and drove it off.
Immediately, I felt a difference in the car in terms of not only how it felt, but how it sounded. Got it out on the highway, and I couldn't believe how much more powerful it was! Felt as though I had gained 20 hp
As a matter of fact, the car felt more powerful than it did when I was catless!Drove it to work today and on the way back, I also noticed another pleasant surprise.
The speed limit on highway 288 is 65 mph. At 65, my car would always be exactly at 2,000 rpm.....now it's under 2,000 rpm by a few ticks.
So apparently, changing the upstream o2 sensors has not only made my car more powerful, it has made it more efficient as well....which means more money saved at the gas station. :thumbsup:
So the moral of the story is, make sure you change your upstream o2 sensors every so often, because they can impact performance and efficiency in a big way since they help the ECU adjust the A/F mixture.
One thing I can't figure out though, is why I had such a big performance decrease the first time after installing the high flow mids
Obviously, it wasn't the high flow mids that was causing the performance loss, but I can't recall the car feeling like it had lost any power whatsoever when I was catless, and the only error code that I had at the time referred to the downstream o2 sensors due to having no cats.
Perhaps being catless was hiding the performance and inefficiency issues caused by the faulty o2 sensor, then after installing the high flow cats, the issues became noticeable?
Since my car has a large engine and is modded, being catless is good for an extra 10 hp to 15 hp easily. Removing the cats would have forced the ECU to readjust the A/F ratio, which takes a few days usually. But if the o2 sensor was faulty, it would not have been able to properly calculate the new A/F ratio for the high flow cats, which explains why the car felt so weak after they were installed....especially after I drove it from my mechanic's shop.
Anyway, how often should the o2 sensors be changed? I'd assume they'd wear out faster on a modified vehicle, due to the faster, hotter exhaust stream?
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