QuestionRoland, we have an '03 PT with non-turbo engine, 28K miles, bought it three months ago so no idea if all original parts under the hood but believe it to be. Starting this week (right before we're getting ready to leave for Christmas on Friday) it started stumbling when you cranked it up in the morning, while in park you can feel it in the seat of your pants, it's idling along then just a quick "bloop," may do it two or three times. No check engine light. No discernible change to tachometer. Now it's starting to get worse, hesitates/stumbles while driving esp. when getting on or off the throttle (stop light, decelerating going down a hill). I took it and had the battery and charging system checked, all OK, added two bottles of Dry Gas, still doing it. Tried to get the codes using the starter on-off-on-off-on but got nothing (didn't give any codes at all.) We're kinda afraid to drive it from KY to NC (5 hours) to visit our folks for Christmas. It's out of bumper-to-bumper warranty but still has powertrain warranty. Chrysler dealer says they'll charge me $80 to look at it. I'd appreciate your advice! Thanks for all your great answers, and Merry Christmas!
AnswerHi Mike,
The post '97 cars don't allow you to get codes using the ignition switch, only attaching a code reader to a plug under the dash will get them. Sometimes an autoparts store, Autozone for example I am told, will do a free readout. But the lack of a check engine light may well mean that it is a fault that isn't detectable by the engine controller.
One of the most common causes of what you describe is an exhaust gas recirculation valve (egr) that is not closing all the way when it needs to (at start up, closed throttle, and full throttle). I don't know which engine is in your PT so I can only say to look for a metal pipe coming off from the main pipe of one of the exhaust manifolds (if you have a V-engine, or The manifold if not) which is routed thru an odd-looking fitting that is itself attached to the intake manifold either directly or via a tube. It has an associated device with vacuum hoses attached to it and usually an electrical device as well.
There is a vacuum operated round fitting on its top, and also a vacuum line going to an electrically operated valve. Look under the round fitting (which is mounted on a saddle with openings for access to view) on the top of the valve where you will see a vertical rod with a slot in it which is the valve stem. Take a straight blade screwdriver and use the slot to lever the valve up against spring pressure and see if it is dropping back down due to spring's action and closing positively. Put WD-40 on the stem to loosen it up in that motion if necessary. Check to make sure the vacuum lines are all attached and not cracked. Then warm up the engine and observe the slot to see if it goes up when you rev the engine to 2500 rpm and then drops back down fully, closing the valve, when you let the engine go back to idle rpm. Make sure that the fully down position is really down because if it is not fully closing when you let go of the accelerator and coast that will cause the engine to stall or sputter. It may be that to get it to close you'll have to unbolt it and clean out the gas flow passage past the valve due to buildup of exhaust fumes in the valve as sticky crud deposit around the internal valve. But usually the WD-40 will loosen up the stem action.
So if you can't find it or have another question, write back and tell me which engine you have. The egr valve is my best suggestion without knowing whether you have any fault codes.
So let me know how it goes.
Roland
