1995 Plymouth Voyager failed emission test.

SPEEDSHOP

MEMBER
1995 PLYMOUTH VOYAGER

Engine Performance problem
1995 Plymouth Voyager 6 cyl Front Wheel Drive Automatic 260k miles

95 grand voyager 3.3 ltr. Failed emission test on High 'HC ppm" on high rev only. Everything else passed on both idle and high rev. Seafoam treated, new plug wires, 6mos old plugs, diaelectric grease, new air filter, oil change 10w-30, gas antifreeze w/91 octane, shrouded pipe leading to cat, new pcv valve. Can anyone 'pin point' the possible cause/cure? Help

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

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.