Failed Emission Inspection

[FirstExplorer]

Just a note for the forum. I had my annual Texas vehicle inpection done for the first time since the mods on my 91 Explorer XLT. The mods are a KKN cold air intake, Magnaflow High Flow Cat, and Magnaflow Catback exhaust. It failed due to high NOx, almost double the limit.

My mechanic thought it was a bad cat. But I reinstalled the stock air filter box and all the vacuum lines and retested. It passed.

This may be a topic that has been discussed before, but the smog check is something that comes up every year.

My conclusion is that the cold air intake on these Explorers may be doing more harm than good. I also do not perceive any difference in performance.
The CAI may also be allowing more raw fuel to pass through accounting for the high NOx. This may not be so good for the cat...it can load it up with crud and reduce its efficiency.

Hope this helps anyone with this mod.

 

[tweakedlogic]

Did you discharge the memory from you ECU? how long have you been driving it before the test.
With all of those mods you getting more air in there than stock. The computer has to relearn new fuel and timing maps.

Disconnect your positive and negative battery cables, turn the ignition switch to on, and touch them together for a few seconds. I also like to depress the bake pedal a few times then let it sit with batt disconnected for a while just to be sure.

 

[FirstExplorer]

I did reset the computer, added 7 gallons of mid grade gas with 10% ethanol, then added a half gallon of Everclear. Then drove 16 miles to flush a gallon of the gasohol through the system and had the test done. My goal was to have about 15% ethanol in the tank. It registered way below the NOx limits.