1995 Jeep Cherokee emissions controls

Engine Performance problem
1995 Jeep Cherokee 6 cyl Four Wheel Drive Manual

Lets try this again, nitrous oxides are at double plus the allowable for this vehicle. All other parameters are well within spec. At half or less of allowable. This generally leads me to the E.G.R. Loop, either the ports are plugged with carbon, or the E.G.R. Valve is not functioning. To the best of my visual, there does not seem to be an E.G.R. At all on this vehicle. I have pulled the throttle body and looked in the intake for any signs of coking or carbon from an E.G.R., But see no signs of such. Is there something else that would raise the NOX levels without affecting driveability? F.Y.I. I am A.S.E. Cert. PARTS not Tech. This is making me nutty. Thanks for your consideration.
Do you
have the same problem?
Monday, October 5th, 2009 AT 6:31 PM

1 Reply

Ok this could be caused by either a bad O2 sensor or a bad Cat. Nox output is higher when the temp is higher this is natural. So with that how hot does you Jeep get? How old is the oil? How old are the spark plugs? If anything here is old or if any plugs are worn then the combustion temps may be getting high which will produce more Nox. If you plugs are new then I would check for the proper heat range too. If the plug heat range is to high then it will raise combustion temps and again produce more Nox. You don't have a PCV it is just a vacuum hose from the intake to the valve cover check the orfice in the manifold where it connects and make sure it isn't pluged. You do have an egr valve, it may be underneath the manifold but there is one, here is a pic of it.


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Monday, October 5th, 2009 AT 7:03 PM

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