Effects of a bad O2 sensor
12-30-2013, 02:56 PM
#1
Junior Member
Thread Starter
Join Date: Oct 2013
Posts: 74
Likes: 0
Received 0 Likes
on
0 Posts
Effects of a bad O2 sensor
I have a 97 grand cherokee with 266k miles and 4.0L engine. Im getting terrible gas mileage as well as it bogging down in second gear and up hills. I have recently done a full tune up, CPS is new, changed coolant, **** was pooh pooh brown.. Still slightly is.
Now i have no downstream O2 sensor which appears to be broke off.. Im curious as to if this is the cause of issues i am having with my ZJ
Now i have no downstream O2 sensor which appears to be broke off.. Im curious as to if this is the cause of issues i am having with my ZJ
12-31-2013, 02:59 PM
#2
Old fart with a wrench
It is my understanding that the upstream 02 sensor is the only one that helps control fuel mixture. The downstream one only monitors the functioning of the convertor. What it does with that info, I haven't a clue.
If your cooling system is that bad, I would recommend a chemical flush. Be sure to pull the block plugs and clean out the holes to get ALL the old coolant out. The chemical flush will clean out the radiator and heater cores.
As far as the mileage is concerned, do you have any trouble codes set? How old is the 02 sensor? Is your throttle body and TPS clean? Check for vacuum leaks at the MAP sensor hose and CCV elbow. As a base line figure, my 97 ZJ 4.0 was getting me AT BEST, 16 highway and 12 local. (242 case)
If your cooling system is that bad, I would recommend a chemical flush. Be sure to pull the block plugs and clean out the holes to get ALL the old coolant out. The chemical flush will clean out the radiator and heater cores.
As far as the mileage is concerned, do you have any trouble codes set? How old is the 02 sensor? Is your throttle body and TPS clean? Check for vacuum leaks at the MAP sensor hose and CCV elbow. As a base line figure, my 97 ZJ 4.0 was getting me AT BEST, 16 highway and 12 local. (242 case)
Last edited by dave1123; 12-31-2013 at 03:13 PM.
01-01-2014, 03:15 PM
#5
Old fart with a wrench
AND, let's get one thing straight. It doesn't seem to matter much weither I'm in 2WD or 4WD, the mileage stays about the same. After all, you're still turning those front gears and shaft in 2WD, driven by the wheels.
01-06-2014, 02:54 PM
#6
Junior Member
Thread Starter
Join Date: Oct 2013
Posts: 74
Likes: 0
Received 0 Likes
on
0 Posts
Thanks guys...
Dave, as for the o2 sensors the upstream as far as I'm aware is stock.. The downstream well it doesn't exist. The tps and throttle body were seafoamed a few months back. The coolant is now a lot better looking.. As for gas mileage in getting 11 city and about 15.5 highway. If i decide to change the upstream do i have to do downstream as well or does that really affect anything too much?
Dave, as for the o2 sensors the upstream as far as I'm aware is stock.. The downstream well it doesn't exist. The tps and throttle body were seafoamed a few months back. The coolant is now a lot better looking.. As for gas mileage in getting 11 city and about 15.5 highway. If i decide to change the upstream do i have to do downstream as well or does that really affect anything too much?
Thread
Thread Starter
Forum
Replies
Last Post
Tcq192
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
7
10-23-2015 09:25 AM
Ye Ol' Cherokee
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
8
10-09-2015 10:29 PM
jeeplover45
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
4
09-04-2015 06:44 AM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
