Isuzu SUV Forum banner

O2 sensors and fuel economy

812 views 4 replies 3 participants last post by  chimpboy 
#1 ·
So, I have a 2000 Rodeo, 3.2, and I read something along these lines: as the O2 sensors age, they still work but their readings go slightly off, such that they can cause the ECU to waste a little fuel, leading to worse fuel economy.

I have no symptoms indicating any O2 sensor problems, but I am sure they are 16 years old, which is probably old enough for me to consider messing around with them (at least in some jurisdictions).

Is this story about their effect on fuel economy plausible/known to be true/bs? Is it worth renewing them just because of their age?
 
#2 ·
It is my opinion O2 sensors do get "lazy" as they age with use, lazy meaning slow to react to changes in the amount of oxygen in the exhaust. The catalyst also can also get lazy with age. Contaminates in the fuel also reduces the efficiency of the O2 sensors and catalyst.
 
#3 ·
If you go for it, you only need to change the ones before the catalysts. The ones after only monitor the catalyst's efficiency and don't control fuel mixture. They can also be a royal PITA to get out with 16 years of heat cycles on the exhaust. Don't use an open end wrench - you'll strip it. Unplug the harness and run it through a box end wrench, or cut it off and use a deep socket. The split sockets suck.
 
#5 ·
I think I'll shelve this idea. I've gotten to do a decent amount of driving now and I can see that the fuel gauge is... a bit screwy. It goes from F to E like it should, but it is not all that linear (and/or it looks empty when there's still a fair bit of fuel left in the tank) and basically made me worry more than I should have. Now that I have done a few actual measurements (drive, record distance, record fuel needed to refill) I see that I am getting about 13.5L/100km (17.5mpg) mixed urban and highway. That included a good open highway run (130km at 100km/h pretty much all the way) as well as some absolutely crap urban driving (a 40-minute drive that took 90-minutes due to traffic.)

That seems to be about on spec, doesn't it? So I am thinking I will leave well enough alone for now.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top