QuestionI have a 1998 Town and Country with a 3.8 litre V6. Recently while returning from vacation, after driving for approximately 8 hrs., the van stalled when stopping at a store. It started back with no problem and continued fine. Two days after the first incident, my wife returned home from work and complained of it running badly. It started fine but when moved into drive or reverse it immediately started "bucking" and subsuquently stalled. While driving, there was no indication of a transmission problem(slipping or and noises). What are the possibile causes?
Thanks
AnswerHi Jeff,
One approach to diagnosing the problem is to see if the engine controller has detected a fault and listed it as a two digit fault code in its memory. There is some ambiguity about whether you can use the ignition key to prompt a readout of the memory or if you need a code reader that plugs into an accessory plug under the dash. The OBD-II system came into effect in '96 and gradually the owner's ability to get the readout faded away depending upon which engine is involved with the problem. But it is worth a try and I'm going to copy in an earlier response to another questioner with a similar situation so you can try to get the codes yourself. If you can't, then the codes can only be obtained with a reader which you can either buy or have attached by a tune-up mechanic and for a charge have them tell you what the code numbers are. Then get a description of the problem, the fix, and the proposed cost and write me back for evaluation if you are uncertain about the diagnosis. It would cost under $50 for the readout.
On the the other hand, from what you describe as the history of the problem I am suspicious that it may be caused by an exhaust gas recirculation valve that is hung up ajar and is not closing at idle and not opening properly when you accelerate the engine and thus causing an improper fuel/air ratio. My car did that recently, again to my wife!
The egr valve on your engine is located at rear corner of the cylinder head, where you will see a pipe that starts at the exhaust manifold between the engine and the firewall and come to the rear and around the corner and ends at the intake manifold area at the rear of the engine. In the pipe you will see a valve with a vacuum hose and another round object also with vacuum hose and wire connector and those two objects are the egr valve and the egr transducer. Look at the vacuum hoses to make sure none of the them are disconnected or leaking at their fittings or cracked. But more likely the valve proper is misbehaving because of a build up of exhaust condensate on the valve stem that is preventing its free movement. If you look closely at the valve you will see inside a flange a small round valve stem that has a slot in its circumference. That stem is attached to the poppet valve inside the body of the egr and that open or closes that return pipe of exhaust gas when appropriate for the running conditions. If the stem is slow in responding to vacuum changes then that will mess up the fuel/air ratio and cause stumbling or dying. So here is what to do as I told the other party:
"Begin by erasing all the existing codes. Just disconnect the negative post of the battery, having first turned "on" the headlights. Then once the battery post wire is disconnected, turn "off" the headlight switch, then wait for 5 minutes and reconnect the negative post. Then do the following, using ignition key: turn it "on-off-on-off-on" and leave it "on" (doing this quickly, no longer than 5 seconds). Then watch the 'check engine' light to begin flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and keep track of the numbers. Repeat the readout and verify the counts are correct. Then group them in pairs in the order that they came out, thus forming two digit numbers. You may notice that the pause is shorter between the digits of a given number, and longer between the numbers themselves. You should only get the number 12 (which means you disconnected the battery recently) and 55 (which means that is the end of the readout).
Then drive the car for a few miles, and re-check the codes again to see if anything new was logged.
Then send me a 'follow-up' question telling me the results of your readouts. I have the troubleshooting manual for several of the engines and we can look up the possibilities of what is wrong based upon what fault codes you show, if any. There is also an essay on fault codes at the site:
http://www.allpar.com/fix/codes.html
which gives the meaning of the code numbers. But then you need to get specific info for what exactly might be the diagnostic tests or parts to replace to complete the repair. (Note that you may get no flashing etc with your '98 engine controller as I mentionned above, Jeff).
Another common reason for failure to idle is that the exhaust gas recirculation valve is sticking slightly ajar due to a build-up of exhaust condensate crud. That valve needs to be closed when the throttle valve is closed at idle or the engine will die. So if you will look for a tube and a mushroom shaped valve connecting the exhaust manifold to the intake manifold you will have found the egr. Inside the "cage" of the mushroom-like cap on the valve you will see a round thin "stem" with a groove around it for easy visualizing movement of the stem. If you can idle the engine, then try revving the throttle valve to maybe 2,000 rpm and back to idle while watching the valve stem for movement. It should jump up and back quickly in response to the throttle revving technique. It if doesn't move or is sluggish then that would be symptom of an ajar valve. You can remove it and check for the condition of the valve if it appears to be suspicious. But it may be corrected simply by spraying WD-40 on the stem where it enters the body of the valve and then lever the stem in and out with a flat blade screwdriver via the slot in the stem to lubricate the passageway where it enters the valve and thus free-up its motion. The stem and valve are mounted sideways so the stem moves horizontally in and out."
So try those two approaches and see if either bears fruit. Let me know what you learn. My similar problem was corrected by freeing up the valve stem with WD-40. There could be other causes, but this would be my first approach to solving it.
Roland
