What to do after changing O2.
10-18-2018 | 10:31 PM
#1
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From: North canaan Connecticut
Year: 01, 99, 98, 98,98
Model: Cherokee
Engine: 4.0
What to do after changing O2.
So I was hesitant to ask this as I’ll probably get the same answers I found researching the subject. But here goes anyway. Just changed upstream O2 in my 98. I’ve been running with it unplugged for a bit because it ran so poorly when connected. I wanted to take it for emissions testing on Saturday which will be less than 48 hours from now. I didn’t want to reset the pcm because I’m concerned all of the monitors will not be set in time. So question is whether or not to reset using my code reader. I’ve basically come to the conclusion that it’s not necessary. It seems though that it will take just as long either way for the adaptive memory to adjust to the new sensors readings one way or the other. All of the monitors are currently set aside from the O2 monitors. So would it take just as long for those to be ready as it would for all of them or would they ready quicker if the others are currently ready? If anyone knows for sure please let me know.
10-18-2018 | 10:46 PM
#2
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Joined: Dec 2015
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From: Syracuse, NY
Year: 1996
Model: Cherokee (XJ)
Engine: 4.0L
If the drive cycle requirements for the monitors that are currently -ready- are longer than the ones that are currently -not ready- then it will take longer to get them all back to ready. So you should not reset anything. The air/fuel adjustments that the computer wants to make after the new o2 sensor was installed and reconnected would have occurred within about 30 seconds - 5 minutes of driving. So don't worry about those, and they are not the same as the readiness monitors. The computer is going to need to see the appropriate drive cycle for the -unready- monitors before it switches them. Resetting things might make the process take longer. Your best bet is to confirm that your fuel trims looks correct after the o2 replacement. Then make some time to take the vehicle on a long and varied drive to encourage the possibility that the drive cycle requirements will be met.
10-18-2018 | 10:48 PM
#3
Old fart with a wrench
Joined: Nov 2010
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From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
If the CEL doesn't reset itself, it will have to be cleared and the monitors will need to go thru a drive cycle. When a trouble code is set, it stops the monitor check sequence. A mechanic with a DRB scan tool may be able to force a check to complete, But I'm not sure. When my WJ set a code for a small evap leak and we fixed it, I went thru several drive cycles and it wouldn't set, like almost 500 miles! In NY, you can pass with one monitor not ready, but I had 2, the evap leak and the 02 sensor heaters. My mechanic programmed an evap check cycle and it cleared, so it passed with the 02 heaters not ready. A couple of days later I checked the monitor status and the 02 heaters were ready as well.
10-19-2018 | 01:14 AM
#4
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From: North canaan Connecticut
Year: 01, 99, 98, 98,98
Model: Cherokee
Engine: 4.0
Awesome! Thanks guys for instilling more confidence in my choice. I’ve always just reset whenever I made any repairs without a worry but I really need to pass emissions soon. And as far as I can remember in CT all of the monitors need to be ready in order to pass.
The only down side is that it’s exactly 1.3 miles from my driveway to my parking space at work so that’s about 5.2 miles I drive just to work and back and stopping home for lunch. And that’s probably 3 warm up cycles if that even matters as much. I guess I’ll have to do a bit of driving between tomorrow night and Saturday morning.
The only down side is that it’s exactly 1.3 miles from my driveway to my parking space at work so that’s about 5.2 miles I drive just to work and back and stopping home for lunch. And that’s probably 3 warm up cycles if that even matters as much. I guess I’ll have to do a bit of driving between tomorrow night and Saturday morning.
10-19-2018 | 03:19 AM
#5
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 730
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
Yeah, take it on a road trip at about 55 for an hour or so, do a little slow stop&go, then return the same way. If that doesn't reset the 02 monitors, you'll have to clear the codes and start over getting the monitors to clear.
I forgot to mention the cars sold in NY have to be equipt with CA emissions. SO I've got 4 02's to worry about! Dual mini-cats and a downstream cat that isn't monitored. Damn liberals anyway! When I bought this XJ, the downstream cat and muffler had fallen off before I bought it. My mechanic just installed an extension pipe, muffler, and tailpipe, then said it would pass NY that way as long as nothing shows up on the computer, which he thinks will not.
I forgot to mention the cars sold in NY have to be equipt with CA emissions. SO I've got 4 02's to worry about! Dual mini-cats and a downstream cat that isn't monitored. Damn liberals anyway! When I bought this XJ, the downstream cat and muffler had fallen off before I bought it. My mechanic just installed an extension pipe, muffler, and tailpipe, then said it would pass NY that way as long as nothing shows up on the computer, which he thinks will not.
Last edited by dave1123; 10-19-2018 at 03:37 AM.
10-19-2018 | 03:50 AM
#6
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 730
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
Ya know? That jeep needs to be run longer then that to stay healthy. SAE recommends any vehicle should be run at least 15 miles after it reaches temperature to expel condensation that builds up in the crankcase. Short trips tend to build sludge because that water isn't removed. Maybe you should make it a point to run it longer on the weekends at least once in a while. As my dad used to say, "Take it out and blow the carbon out if it!" "Dad, are you advocating street racing?" LOL!
10-19-2018 | 09:04 AM
#7
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Joined: Dec 2015
Posts: 2,139
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From: Syracuse, NY
Year: 1996
Model: Cherokee (XJ)
Engine: 4.0L
Awesome! Thanks guys for instilling more confidence in my choice. I’ve always just reset whenever I made any repairs without a worry but I really need to pass emissions soon. And as far as I can remember in CT all of the monitors need to be ready in order to pass.
The only down side is that it’s exactly 1.3 miles from my driveway to my parking space at work so that’s about 5.2 miles I drive just to work and back and stopping home for lunch. And that’s probably 3 warm up cycles if that even matters as much. I guess I’ll have to do a bit of driving between tomorrow night and Saturday morning.
The only down side is that it’s exactly 1.3 miles from my driveway to my parking space at work so that’s about 5.2 miles I drive just to work and back and stopping home for lunch. And that’s probably 3 warm up cycles if that even matters as much. I guess I’ll have to do a bit of driving between tomorrow night and Saturday morning.
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10-19-2018 | 09:56 AM
#8
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Joined: Oct 2015
Posts: 7,421
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Year: 2000
Model: Cherokee (XJ)
You would be surprised how quick all your monitors can come up. In my '00 in 26 miles last time I checked. With my Jeep the one that takes the longest is the Evap and looks like a direct correlation to the amount of fuel in my tank. 3/4 full or more makes it come up quick.
10-19-2018 | 03:36 PM
#9
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From: North canaan Connecticut
Year: 01, 99, 98, 98,98
Model: Cherokee
Engine: 4.0
@ Dave, I know that short trips are less than ideal for condensation burn off and what not that’s why I always let my vehicles get up to temp 99% of the time that I start them. I will usually let them idle until operating temp has been reached if need be. Even though idling too much isn’t necessarily good either but it’s better than condensation build up. I keep up on the oil changes as well. And I just sold my wife’s 01 which had the 4 sensors, never had to replace them though.
@ Jordan, I am familiar as well with drive cycles as well. I actually worked at a dealership for a bit and used to take cars on drive car for runs often. But they were always newer and not Jeeps. I only mentioned warm up cycles because I wasn’t sure if drive cycles alone would be enough.
Thanks for all all the help guys but I have read a few times of vehicles taking 500 miles to turn the CEL off. Also I experienced a little hesitation earlier which I hadn’t whilebthe o2 was unplugged. I think I’m just going to reset and drive it as much as possible and see where I end up. I don't want to wait to find out if the CEL will turn itself off. I’d rather reset and see if the light comes back on. And hopefully it won’t take 500 miles to ready the monitors. If I don’t get it through the testing tomorrow oh well.
@ Jordan, I am familiar as well with drive cycles as well. I actually worked at a dealership for a bit and used to take cars on drive car for runs often. But they were always newer and not Jeeps. I only mentioned warm up cycles because I wasn’t sure if drive cycles alone would be enough.
Thanks for all all the help guys but I have read a few times of vehicles taking 500 miles to turn the CEL off. Also I experienced a little hesitation earlier which I hadn’t whilebthe o2 was unplugged. I think I’m just going to reset and drive it as much as possible and see where I end up. I don't want to wait to find out if the CEL will turn itself off. I’d rather reset and see if the light comes back on. And hopefully it won’t take 500 miles to ready the monitors. If I don’t get it through the testing tomorrow oh well.
10-19-2018 | 05:39 PM
#10
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Joined: Jan 2015
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From: North canaan Connecticut
Year: 01, 99, 98, 98,98
Model: Cherokee
Engine: 4.0
So about 10 minutes after my last post I started my jeep to head back to work, drive about a half mile and realized no CEL. I’m home now and I plugged in the reader and it has p0132 as a freeze frame and p0135 pending. Also oxygen sensor, oxygen sensor heater, catalyst and evap monitors are not ready. I just replaced the hose from the tank to the vapor canister so that’s why the evap monitor is not ready. Looks like I might also need a cat or downstream o2 sensor. Just going to have to drive it for a week I guess and see where it goes from there.
10-19-2018 | 05:46 PM
#11
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Year: 2000
Model: Cherokee (XJ)
As far as the P0135 goes did you check the Fuse in the PDC? In my '00 I am pretty sure it is one of the 20 amp regular fuses on the right hand side when standing in front of the Jeep. My understanding is '00 and '01 PDC's are set up a little different then '99 and down though.
10-20-2018 | 07:24 AM
#12
Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 730
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
I was talking to my mechanic buddy and he says it's very difficult to try to explain to customers why they need to complete a drive cycle and what that entails. They are impatient and can't understand that the problem is fixed, it's just that the vehicle has to learn that the problem is no longer there. His explanation was the best I've heard yet. He said some of them just can't get it thru their thick skulls that computers are stupid, now don't be stupid yourself.
10-21-2018 | 12:30 AM
#13
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From: North canaan Connecticut
Year: 01, 99, 98, 98,98
Model: Cherokee
Engine: 4.0
Well maybe I was jumping to conclusions. I went for a drive last night, another this morning and then a nice longer drive with some highway this evening. This morning when I checked, the catalyst was ready. Still the evap and o2 not ready. P0132 freeze frame remains but the p0135 no longer pending. Then about 5 minutes ago I checked and it’s only the evap remaining not ready and the freeze frame still stored. Not sure but I may have to test some components of the evap system. I’m pretty sure the shop near me has been able to force an evap monitor test on one of my parents vehicles before after doing some repairs. I may need to have this done myself.
10-21-2018 | 01:49 AM
#14
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Joined: Oct 2015
Posts: 7,421
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Year: 2000
Model: Cherokee (XJ)
Awesome! Thanks guys for instilling more confidence in my choice. I’ve always just reset whenever I made any repairs without a worry but I really need to pass emissions soon. And as far as I can remember in CT all of the monitors need to be ready in order to pass.
The only down side is that it’s exactly 1.3 miles from my driveway to my parking space at work so that’s about 5.2 miles I drive just to work and back and stopping home for lunch. And that’s probably 3 warm up cycles if that even matters as much. I guess I’ll have to do a bit of driving between tomorrow night and Saturday morning.
The only down side is that it’s exactly 1.3 miles from my driveway to my parking space at work so that’s about 5.2 miles I drive just to work and back and stopping home for lunch. And that’s probably 3 warm up cycles if that even matters as much. I guess I’ll have to do a bit of driving between tomorrow night and Saturday morning.
Well maybe I was jumping to conclusions. I went for a drive last night, another this morning and then a nice longer drive with some highway this evening. This morning when I checked, the catalyst was ready. Still the evap and o2 not ready. P0132 freeze frame remains but the p0135 no longer pending. Then about 5 minutes ago I checked and it’s only the evap remaining not ready and the freeze frame still stored. Not sure but I may have to test some components of the evap system. I’m pretty sure the shop near me has been able to force an evap monitor test on one of my parents vehicles before after doing some repairs. I may need to have this done myself.
https://www.smogtips.com/smog-questi...tors-Not-Ready
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10-29-2018 | 11:46 AM
#15
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From: North canaan Connecticut
Year: 01, 99, 98, 98,98
Model: Cherokee
Engine: 4.0
So I inquired with a friend who’s family owns the shop nearby. He said CT will pass if one monitor is not ready. He also said that the evap year doesn’t run as often when temps are below 40ish. Not sure if it’s because there isn’t as much fuel vapor when it’s cooler or what.
I checked last last night and the evap monitor was finally ready. Just went and had it tested and all is good. Made it 48 hours before my free retest period was up. Lol.