Gas mileage
06-21-2018, 07:34 AM
#15
Senior Member
Join Date: 09-07-2008
Location: Mebane, NC
Posts: 1,016
That is exactly where I was going. I have seen situation where the O2 sensors are lazy and the fuel economy goes down, replace the sensors fuel economy is restored. FYI the if the front sensor, that is the one that has an impact on the trims, the only reason for the 2nd is to check cat efficiency.
The mile mark where i replace them is around 100k. In the situations where I've seen it impact economy the mileage was in excess of 100k so that is what I use for my reasoning.
The mile mark where i replace them is around 100k. In the situations where I've seen it impact economy the mileage was in excess of 100k so that is what I use for my reasoning.
06-21-2018, 09:19 AM
#16
Technical Moderator
Join Date: 01-23-2009
Location: Fredericksburg, Virginia
Posts: 24,660
Could be, but:
"lazy" is measured in milliseconds; if lean/rich transition is more than 200 milliseconds or rich/lean transition is more than 130 milliseconds there would be a P0133 code.
If the cat was plugged up there would be a P0420 and other symptoms, like greatly reduced power.
"lazy" is measured in milliseconds; if lean/rich transition is more than 200 milliseconds or rich/lean transition is more than 130 milliseconds there would be a P0133 code.
If the cat was plugged up there would be a P0420 and other symptoms, like greatly reduced power.
06-21-2018, 12:25 PM
#17
Senior Member
Join Date: 09-16-2013
Location: Tampa, Florida
Posts: 1,408
Could be, but:
"lazy" is measured in milliseconds; if lean/rich transition is more than 200 milliseconds or rich/lean transition is more than 130 milliseconds there would be a P0133 code.
If the cat was plugged up there would be a P0420 and other symptoms, like greatly reduced power.
"lazy" is measured in milliseconds; if lean/rich transition is more than 200 milliseconds or rich/lean transition is more than 130 milliseconds there would be a P0133 code.
If the cat was plugged up there would be a P0420 and other symptoms, like greatly reduced power.
06-21-2018, 08:33 PM
#19
Administrator
Join Date: 10-13-2011
Location: Welland,Ont Canada
Posts: 36,441
If the cats core has been contaminated with either oil or Dexcool , additives area going to clean it out.
I cut open the cat on my 1988 after it had a melt down and the core was melted solid.
That caused my brand new 355 SBC to have a bad reaction and crack the block and passengers side cylinder head from the pressure, and me putting in additives, thinking it was going to clear it up.
Another new 355 and new hiflow Magnaflow cats, cured the problems
Cha-Ching!! $7,500.00 in damages.
I cut open the cat on my 1988 after it had a melt down and the core was melted solid.
That caused my brand new 355 SBC to have a bad reaction and crack the block and passengers side cylinder head from the pressure, and me putting in additives, thinking it was going to clear it up.
Another new 355 and new hiflow Magnaflow cats, cured the problems
Cha-Ching!! $7,500.00 in damages.
06-23-2018, 11:13 PM
#20
Thread Starter
Join Date: 06-18-2018
Location: Florida
Posts: 7
Well I got home today and now my mileage is down to 24.5 highway. I replaced the downstream o2 sensor because that's all anyone in town had. My car has 145,000 miles on it. I still am not getting any codes. I have to leave for Oregon tomorrow due to a death in the family so I'll see what happens. It's 5,000 miles round trip so maybe it will set a code so I can see what's going on. I may be able to find an upstream 02 sensor out there.
