Is the problem only on a cold engine, hot or both?
is the hot engine reaching and holding 180F or more as it must?>
its running rich
and that is misfire.
lots of causes for rich. the tests are easy in shop with tools.
cracks in the exh header, there must not he any leaks in that header (or bad gaskets)
or the 02 lies. , goes to 0volts and then engine runs rich as a piggy. (my scan tool shows this is seconds, 02 flat-lined at 0v.
all cars, with 02 do that. with that issue.
02 means oxygen sensor, the front one, not the rear one.
Testimonial: "i will check all imformation you have given me .thanks for your time seems like your the only one that same problem"
fixed jeep front o2 sensor disconected it runs great
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SOURCE: 2000 Ford Explorerer rough idle When cold
what codes are present? If it is lean codes P0171/P0174 problem is most likely the orings leaking between upper and lower intake manifold if this is a 4.0L
SOURCE: 99 Expedition, runs rough, won't idle, no power.
it could be two things a bad injector or a the intake gaskets are leaking
SOURCE: 1996 Honda Accord Rough Idle Even After tune up
Perform a valve clearance inspection and adjust if necessary. Tight or sticking valves will cause a misfire or rough running concern. Note: Perform valve adjustment when the engine is stone cold. 4cyl: INT 0.26mm EXH: 0.30mm (V6 engine are hydraulic and no adjust necessary.) Also check for a sticking or stuck open EGR valve. For diagnostic purposes only: Remove the EGR valve. Place a business card over the EGR passage and bolt the EGR valve back on. This plugs the EGR ports and if the misfire goes away the EGR valve is partially stuck open and is defective.
Check for low fuel pressure. Check for low compression. Check cam timing. Check for a weak ignition coil. Also don't over look the possibility of worn or broken engine mounts which cause excessive engine movement and engine vibration. -hope this helps
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