Chrysler Repair: Roland, We did just as..., spark coils, dodge caravan

Question
Roland,

We did just as you said on our 1996 Dodge Caravan 3.3 ltr engine.  You are right that we haven't had to call a tow truck - yet.  It just stalls whenever it wants to - or so it seems.  We checked the flash codes and came up with 12-55.  We found that 12 relates to battery and I think they had to disconnect that recently to replace the 02 sensors.  Could it be another battery problem?  The mechanic thought the fuel pump was in good shape.  We appreciate your help.

Answer
Hi Tricia,
No, I doubt that the 12 code has anything to do with it, that code will be set whenever you disconnect the battery but will disappear after 50-100 igniton key cycles.
As for the stall, if there is no fault code, then the items to consider are usually related to the fuel mixture, the spark coil, or emission system which are less well overseen by the engine controller so it may not have a code for some of those. Next time it dies the things to consider are: is the fuel pump running (you will normally hear it whir for about 1 second after you turn on the ignition switch to the run position, so familiarize youself with that sound), is the spark getting to the spark plugs (the easiest way would be to have an extra plug on board, then remove the insulator cap from one of the plugs in the engine and insert your spare plug in the cap, then hold the threaded shell of the plug against the cylinder head or any other metal part on the engine you can reach to privide the ground pathway, and recuit a helper to try the starter. Observe whether you get a spark jump across the electrodes of the spark plug. Try this on several different plug wires as there are actually 3 different spark coils in the spark package for that engine.  Let me know if that is the problem and we'll give you some more ideas.
The egr valve might be getting a little sticky and failing to close when you are coasting or idling as it should do. So find the valve, located in the pipe from the exhaust manifold to the intake manifold, and inspect the stem inside the "cage" as you rev the engine from idle. there is a slot in the stem to aid you view its motion. If it doesn't open and close quickly then spray some WD-40 on the stem where it enters the valve to loosen up the action, and use the tip of a screwdrivejr in the slot to lever the valve open and closed to lubricated the stem.  
The other item that can be troublesome is the MAP sensor located on the front side of the intake manifold) which can become inaccurate without setting a fault code. I had that happen to me once. If you have a volt meter you can see what it reads when you just turn on the ignition and then when the car stalls recheck that voltage with the engine at rest (put a fine pin thru the insulation of the dark green/red wire to connect to the internal conductor
making as small a hole as practical, then read the voltage between the pin and ground with the plug connected to the MAP). It ought to be around 4.6V.The voltage between the other two wires at the MAP plug (when unplugged) should be 5V.
Keep checking for codes when you stall, as one may be below the threshold for detection but then will be detectable.
An intermittant stall requires that you are ready to make the observations at the time of the stall; the shop time to let them find it is prohibitive.

Roland