This is for a friends grandma who is the widow of a WW2 vet. She is 85, still strong and likes being independant. Her minivan has gone tits up and my buddy and I are trying to fix it for her.





Its a 96 Plymouth voyager 2.4L automatic about 115K miles, doesnt smoke and is overall in very good shape. We get a code 43 when we scan the ECU for codes.





Starts fine, and runs good when cold, idles and sounds great until it reaches operating temp. Once it gets warm it misfires, hesitates, stumbles and shakes horribly. On the dash we can get it to flash a code 43 which means its getting a misfire. We can't drive it to autozone because it might leave us stranded.





So far we have checked all the vaccuum lines for leaks, checked the intake manifold for leaks with carb spray, changed the camshaft position sensor, changed the spark plugs, checked the plug wires for nicks and or cuts, checked the coils, and cleaned out the IAC valve. One thing strange about this vehicle is that we could not find the EGR valve.





What I am guessing is that one of the sensors is throwing it off once the computer takes over to control the emissions, hence why it only does it when its hot. I hate to have my buddy start throwing money at it randomly since we already replaced the camshaft sensor at $75 bucks and that wasnt the problem.





Weve been reading online and some folks say its the MAP, some say its the O2 and some say it could be the coolant temp sensor.





Im puzzled by this. Any help would be appreciated.

 

I dont know if this will help but I had similar issues with my 1995 with the 3.0 six.  It wound up being a broken wire from the ignition module in the distributor to the ECU.   I disconnected the pigtail connection from the distributor and used jumper wires to reconnect it.  started the engine and removed one wire at a time until nothing changed(engine didn't die but ran just as badly).  Then chased the wire to the ECU and replaced it.  Runs great now.  

ETA  you may have to do this with the camshaft sensor.  With mine the ignition module was also the used as the crankshaft sensor.  When the ECU
doesn't see a signal from the cam/crank sensor it guesses when to fire the plugs.

Thanks for the input. I'll have to check the wires for continuity then.



 

I took a quick look here..http://www.obd-codes.com/
Seems to indicate a bad O2 sensor.

Sounds like Distributor.

O2 sensor runs about $35 from rock auto. I would start there. A new set of plug wires could not hurt. Also try to get some Mass Air Flow sensor cleaner and clean the MAF.

This vehicle is DIS ( distributorless Ignition ). NO Mass aitflow on this vehicle either. O2 sensor would trip a fault code for the O2 if it was bad. I can always take voltage readings off of it. Not to say that its not bad. Just something I have to check.

disconnect the cat and see what happens.

Look real hard at the temp sensor, it may be fine but spike at a certain temp. You will have to watch it with a voltmeter from cold to warm. It has been a long time, but if it is stumbling when hot, and you have over 1 volt at the O2 sensor, it isn't your problem. Those are your most likely problems, if it works fine when it is cold.

Thanks. I'll definately look into that.

Good idea here!  Check to make sure you have no restriction in exhaust flow.  Place your hand away from the tailpipe and feel the flow first.  If it feels insufficient, disconnect the cat, or remove the O2 sensor and check for excessive back pressure.  Does the rough running when warm happen when idling also?

When its cold it runs fine. Its only when it gets up to a warm temp that it starts to fail.



 

Which is why you should check the cat.  It will run fine for a period of time.  As it runs, the CAT starts getting restricted from the solids in the exhaust stream, this restricts the overall exhaust flow, causing power loss, misfires, rough running, and if bad enough, even stalling.

Coil.

i speak from experience. same  motor and mileage, started @ 114K. throw money away on multiple diag fees, when it takes jack stands some good rust penetrating spray around the exhaust manifold and cat hardware. let it work over night drop the cat,or loosen up @ manifold then see what happens.
Some performance issues after 80-100K while not appearing until op temp or afterwards usually point to an emissions/exhaust issue.

Check the temp sensor.

When the vehicle is at operating temperature, does it idle ok?  If it idles alright, I take it the vehicle stumbles upon acceleration and has no power.  Am I correct?

Had a 93 voyager.  It would run fine until it ran for a few minutes.  The car would then cut off while driving around with no codes thrown.  It would restart immediately about 10% of the time but waiting a few minutes it would normally restart.

 Turns out that the computer was bad and had to be replaced.  I do not know how you can test the computer.

Update: Got it fixed. Took a guess on the crankshaft position sensor. While I was taking it out it broke so regardless I had to buy one. Got the new one and put it in. It fixed the problem.