1994 Jeep YJ Smog test

SODAASH

MEMBER
1994 JEEP WANGLER YJ

Engine Performance problem
1994 Jeep YJ 4 cyl Four Wheel Drive Manual 113k miles

hello
im tring to get my Jeep smog and it keeps failing NO (ppm) at 15mph. It passes at 25mph. It doesnt have a EGR ive already tried looking there but for some reason the 2.5L engine doesnt have one. I replaced spark plugs, wires, router and cap. An oil change has been done. Not sure what else I can do ive looked for vacum leaks but didnt find any. Is there any thing else I can do to bring down the NO?

5 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Normally points to EGR valve

Could be caused by a bad three-way converter or a computer control system that remains in open loop meaning the computer throwing fuel at it all the time bcuz of a failed coolant temperature sensor. Is the engine getting hotter than usual if so it will raise the engine combustion chamber to form oxides of nitrogen

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Wednesday, October 28th, 2009 AT 8:14 PM

SODAASH

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Doesnt seem to be over heating. I just got the car this weekend but the gage never goes above 210 and the car doesnt seem like its real hot but like I said I just got the car so im not sure what the normal temp is suppose tobe.

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Wednesday, October 28th, 2009 AT 8:40 PM

RASMATAZ

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You're good on 210deg check the other stuffs I've mentioned and comeback with some results

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Wednesday, October 28th, 2009 AT 8:43 PM

SODAASH

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How can I check to see if the cat is working?

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Wednesday, October 28th, 2009 AT 8:52 PM

RASMATAZ

MECHANIC
75,992 POSTS

Take it to a shop that does smog testing and have them sniff out the 5 gases with TAS machine this will tell if its doing its job/meaning scrubbing the gases.