Hi I have a 94 cherokee with the i6. Just took it to get smogged and it passed every category with flying colors except the NOX test at 25 mph. At 15 mph it is below average for NOX. Im told this is caused by heat in the combustion chamber, which can be caused by a lean air to fuel ratio.in the past 6 months I have replaced many of the fuel system components including fuel pump, fuel filter, injectors, fuel regulator, thermostat, radiator, o2 sensor, cleaned the computer prongs and installed a new cat convertor. What else could be causing this?
CF Veteran
Whats the mileage? The combustion chambers may be in need of a good cleaning. When was its last tuneup? And when was the cooling system serviced last? Out of curiousity, what brand o2 sensors are you using? NTK is best. Aftermarkets dont always work like theyre supposed to.
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150k. I've done 2 solid seafoam cleanings. It's gotten a full tune up ( plugs,wires,rotor cap,oil,oil filter,radiator flush) about 5 months ago and the old components were still in good condition. I've replaced the radiator with an all aluminum one and installed a 160 tstat as well. The sensor is Bosch. I think my next step is checking the map sensor and egr...Originally Posted by fb97xj1
Whats the mileage? The combustion chambers may be in need of a good cleaning. When was its last tuneup? And when was the cooling system serviced last? Out of curiousity, what brand o2 sensors are you using? NTK is best. Aftermarkets dont always work like theyre supposed to.
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it was getting a tad bit hotter than 210 but I mainly installed it to make sure I wouldn' have any overheating problems when taking it out wheeling.Originally Posted by fb97xj1
The factory t-stat should be a 195. Normal operating temp is 210. Why the 160? Was it overheating?
CF Veteran
Try this:
https://www.cherokeeforum.com/f30/st...226299/index4/
And, as fb stated, the NTK/NGK's are the only O2 sensors that will function properly in the XJ's. All the other brands (including Bosch) will produce wonky results and numbers with runnability.
Follow up with the EGR and MAP as you were going to and let us know how it goes. I'm subbing to this thread out of curiosity in how your re-test goes.
https://www.cherokeeforum.com/f30/st...226299/index4/
And, as fb stated, the NTK/NGK's are the only O2 sensors that will function properly in the XJ's. All the other brands (including Bosch) will produce wonky results and numbers with runnability.
Follow up with the EGR and MAP as you were going to and let us know how it goes. I'm subbing to this thread out of curiosity in how your re-test goes.
Quote:
https://www.cherokeeforum.com/f30/st...226299/index4/
And, as fb stated, the NTK/NGK's are the only O2 sensors that will function properly in the XJ's. All the other brands (including Bosch) will produce wonky results and numbers with runnability.
Follow up with the EGR and MAP as you were going to and let us know how it goes. I'm subbing to this thread out of curiosity in how your re-test goes.
ok, I've ordered a new map sensor and egr solenoid and plan on cleaning out the egr valve sometime this week. I'll keep you posted on the resultsOriginally Posted by 4WD4EVER
Try this:https://www.cherokeeforum.com/f30/st...226299/index4/
And, as fb stated, the NTK/NGK's are the only O2 sensors that will function properly in the XJ's. All the other brands (including Bosch) will produce wonky results and numbers with runnability.
Follow up with the EGR and MAP as you were going to and let us know how it goes. I'm subbing to this thread out of curiosity in how your re-test goes.
CF Veteran
Your xj has a egr valve the only thing it does is lower nox make sure that it is working and the ports are clean .