Chrysler Repair: 1996 Chrysler Sebring JX rough idle, chrysler sebring jx, obd ii codes

Question
Hi Kevin. I have a 1996 Sebring JX Convertable 2.4 cyl. It has a rough idle that I can't seem to tackle.I cleaned the Throttle housing,the ERG tube. I also cleaned the egr and applied a light oil on the shaft of the EGR valve.Wires were original so I replaced them as well as the plugs,mostly for piece of mind though. It runs great going down the road but when the idle settles down it begins to lobe. No codes are present either. Data looks good on the scanner.I also should ad that I replaced the Throttle body gasket and the EGR and EGR tube gaskets when I R and I'd them to decarbon. EGR does hold vacuum.Any suggestions?

Answer
Hi Wayne,
Have you checked the compression on the cylinders? You see, to have 'hit' the most obvious electrical and mixture related items. It is surprising to me that you don't have a code for "missing" as by '96 you should have the full range of OBD-II codes that would include sensing such a situation. It leads me to wonder if there might be a communication failure in the computer but even that would have a code. But that is suspicious. Did you try for codes using the ignition key and check engine light flashing approach: "on-off-on-off-on and leave 'on'" doing that in 5 seconds or less elapsed time? I believe the '96 model year still had the capability.
Other possibilities: an intake manifold leak (spray perimeter with short spritz's of starter fluid, listening for change in idle).
Injectors? PCM grounds? Pull plug wires one at a time to see if it is centered on one cylinder? Timing marks line up of cam sprockets/crankshaft check? Vacuum gauge readings/needle vibration analysis? Those are the "classic" approaches I can suggest.
Good luck, and let me know when you find out what it is, please.
Roland
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