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Smog...

S

SanDiegoOverland

NAXJA Forum User
Location
San Diego
= :guitar: Pass!! :guitar:

I always get nervous for some reason..haha! Anyone else get all tingly when "the man" comes over and says, "She passed, you're all set"? :D

My NO and CO WERE a bit higher than I would like, though, at 15mph.

Funny thing is - they're very close to the listed average when at 25mph...

QUITE a bit of difference actually.

NO was up around 600 @ 15mph, but down around 200 @ 25mph.

CO was similar in its change depending upon speed.


Any thoughts? I'm thinking it's probably time for a new cat since the one installed looks like the OE unit, but it seems to be working at higher speeds?

1992 4.0L HO/AW4/Np231/202,000 miles
 
Hehe, my last 4 or 5 cars had to go to "special" smog stations, so it is a nice feeling to have a vehicle that can go to a normal smog spot and pass.

Mine did so well this year, the guys' like, "wow - this Jeep runs great; you wanna sell it??"
 
Just failed smog.

Apparently my check engine light is out and I had a stored code I wasn't aware of.

The code is a P0138 O2 sensor High voltage (Bank 1, Sensor 2).

The other issue is I failed NO at 15 mph. Got a 604, max is 508 and avg is 90. At 25 mph, I passed easily at 69.



I guess my question is this... should I expect changing the O2 sensor to fix the NO reading at 15 mph, or is there other things I should do before the re-test?


Also, how many miles do I have to drive to "reset the computer". The folks at the smog shop said Chrysler cars require a lot of miles... maybe up to 500. Is that right?

Thanks,
Mike
 
Smog guys are FOS.


Change the check engine lamp, that being burnt out is also an instant fail on the visual test. Change out the downstream O2, have somebody reset the codes, then try again.

Drive cycle is not 500 miles, there is a series of benchmarks it needs to hit but you should be able to do them in 50 miles or so. Give it freeway as well as city traffic. If you have access to a scan tool they usually will indicate the system readiness.
 
GSequoia said:
Smog guys are FOS.


Change the check engine lamp, that being burnt out is also an instant fail on the visual test. Change out the downstream O2, have somebody reset the codes, then try again.

Drive cycle is not 500 miles, there is a series of benchmarks it needs to hit but you should be able to do them in 50 miles or so. Give it freeway as well as city traffic. If you have access to a scan tool they usually will indicate the system readiness.
Click to expand...

Thanks.

I have a scan gauge, so I can reset the codes. Since the Check Engine light is out, I didn't even bother to check codes before I smogged it.

Not sure about it telling me the status of system readiness? I can scan and it tells me how many stored codes... but I don't see a system status anywhere? I'll do some research on that.


Thanks very much.

I'm off to change the O2 sensor.
 
downstream o2 shouldnt effect the way it runs, ASAIK. i thought it was just there to alert the ecu if the cat was working.
 
ocean_jet said:
Just failed smog.

Apparently my check engine light is out and I had a stored code I wasn't aware of.

The code is a P0138 O2 sensor High voltage (Bank 1, Sensor 2).

The other issue is I failed NO at 15 mph. Got a 604, max is 508 and avg is 90. At 25 mph, I passed easily at 69.



I guess my question is this... should I expect changing the O2 sesor to fix the NO reading at 15 mph, or is there other things I should do before the re-test?


Also, how many miles do I have to drive to "reset the computer". The folks at the smog shop said Chrysler cars require a lot of miles... maybe up to 500. Is that right?

Thanks,
Mike
Click to expand...

I have the same code also. I changed the O2 sensor and its a pending code on my code scanner. Im wondering if resetting the Jeep's computer versus clearing the code on my handheld will take care of the issue.
 
Wiser said:
I have the same code also. I changed the O2 sensor and its a pending code on my code scanner. Im wondering if resetting the Jeep's computer versus clearing the code on my handheld will take care of the issue.
Click to expand...

After changing the sensor it kept throwing the code. I diaconnected the battery for 10 minutes. That seemed to clear it. It's not throwing any codes now.
 
Vanimal said:
downstream o2 shouldnt effect the way it runs, ASAIK. i thought it was just there to alert the ecu if the cat was working.
Click to expand...

That's what I am afraid of. I changed the sensor, but I don't want to pay for retest if the NO is not fixed.
 
Thanks for the help everyone.

Passed!

NO at 15 mph came in at 142 after changing out both O2 sensors.
 
if they're the same age, it's likely that the upstream o2 is not too healthy if the downstream one isnt. changing the upstream one probably did the trick.
 
YOu people and having to smog your XJ's..
glad you passed, the ones that did.
 
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