QuestionQUESTION: My Intrepid is running rough when I accelerate, but only sometimes, other than that it runs smoothly. It feels like the timing is off every other stoplight.Has not stalled yet. Replaced the plugs,wires,pcv valve,and crankshaft position sensor last year when it would stall for no reason and be difficult to start. Replaced fuel filter after current problem began, but it did not help. There are no codes (except 12 and 55).
ANSWER: Hi Chris,
I would take a look at the function of the exhaust gas recirculation valve which is located in a small pipe that connects a return line from the right (passenger) side exhaust manifold to the intake manifold, near the throttle body. That valve could function well enough to not set a fault code, yet it could cause a lean mixture and resulting stall when slowing down to stop. It is bolted into the pipe. It has a vacuum line attached to an electrically operated solenoid nearby.
The item you want to check is the valve stem, located between the valve's round top and the body of the valve bolted into the pipe. The stem is hidden a bit by a flange that is between those two parts of the valve but look inside the flange for a rod that has a circumferential slot. That is the stem. You can put a screwdriver tip in the slot and move the stem back and forth. An internal spring will help to close the valve. You want the valve stem to return to that closed position positively, to a dead stop. If it isn't doing so or seems sticky in its action then spray some penetrating oil like WD-40 on the stem where it enters the valve body, then work the stem back and forth until it move well and closes positively. That may be the answer to your problem as if the valve sticks ajar it will lean out the mixture and cause a stall like you describe. It will also cause a stall/hesitation if you step on the gas.
Please let me know if this corrects your problem.
Roland
---------- FOLLOW-UP ----------
QUESTION: My car doesn't stall, it just runs rough when I accelerate-(just not all the time). Other times it accelerates smoothly,like nothing is wrong. Would the EGR valve cause an intermittent problem like this? Would the electrically operated solenoid cause the EGR valve to operate improperly without causing a fault code?
AnswerHi Chris,
Runs rough/stall... not that different, just a matter of degree. Yes, the valve could be intermittently sticky/temperature dependent, so that would not be unusual. The solenoid (transducer), if it were faulty, would set the code because that solenoid is used to test the egr under the command of the powertrain control module which would set the fault code when it didn't produce the proper response. That is why I believe it is the mechanical aspect of the valve not closing, as opposed to the transducer not opening it, that is causing your problem. It is a theory, but I seen it enough to recommend that you take a look at this. No big deal, just a few minutes of your time to locate it and check it out.
Roland
