1995 Jeep Cherokee wont pass emission test

Tiny
KEKEG92
  • MEMBER
  • 1995 JEEP CHEROKEE
  • V8
  • AWD
  • AUTOMATIC
  • 218,000 MILES
I have taken my truck 4 times and can not pass emission test. I am being told that the hc, and nox is high. So I dont know what to do
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Sunday, September 6th, 2009 AT 4:47 PM

1 Reply

Tiny
RASMATAZ
  • EXPERT
Hydrocarbon failures mean unburned gasoline is passing through the engine and entering the exhaust. The three most common causes include ignition misfire, lean misfire and low compression (typically a burned exhaust valve). Ignition misfire can be caused by worn or fouled spark plugs, bad plug wires or a weak coil. Lean misfire results where there is too much air and not enough fuel, so check for vacuum leaks, dirty injectors or a fuel delivery problem. In addition to these, hydrocarbon failures can also be caused by oil burning due to worn valve guides, valve guide seals and/or rings.

NOX failures are usually EGR-related, since the EGR system is primarily responsible for reducing oxides of nitrogen. But NOX emissions can also be caused by a bad three-way converter or a computer control system that remains in open loop
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Sunday, September 6th, 2009 AT 6:06 PM

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