Chrysler Repair: 2.5L V-6:missing/hard start/poor idle/no codes, spark plug wire, o2 sensors

Question
QUESTION: Hi,

I looking for the location of the Code Reader Hook up.  The engine is ideling rough and it stalls after it rooms up when idelingg.  I just cleaned the EGR valve and it appears to be working.  So I thought I should use the reader to see what is going on with the different read outs on the o2 sensors.

Thanks,

ANSWER: Hi Frank,
I believe you will find just behind the lower edge of the dash, slightly to the left or right of the steering column. But because you have a '96 you also have access via the check engine light. Use the ignition key:"On-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light, which stays "on", to begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat to be sure you have the counts accurately. Then use the "thank/rate" tab to get back to me with the count results in the order that they came out. You won't have to wait for me to be 'available' to take another question that way.
Roland

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QUESTION: Hi Roland,

OK, I found the Code Reader hook up.  Actually I just wanted to check the readings on the O2 sensors to make sure they are working.  I didn't have a engine check light so there were no codes.

The care is idling rough and will stall when you come up to a stop.  Hard to restart.  Funny thing is, while I am in my garage, it will set there and idle, rough and smells kind of rich.  When I back down the drive way and put it into gear it well usually die.  Then hard to start.

Since I sent the last email I found that the distributor cap was missing the bottom screw.  I thought I had found the problem.  Also found a spark plug wire not seated correctly and had corroded.  So I replaced the Cap, rotor and cleaned and fixed the plug wire.  Still the same.

Replaced the MAP Sensor this morning. Still the same.

So now I'm wondering, could the distributor cap problem cause spark plugs to be fouled and cause this problem?  I pulled one out and looked at it and it looked OK.  This is a 2.5 V6 so 3 of the plugs are under the intake manifold. :o( .... I was reading the man who replaced the crankshaft sensor and wondering if I should go for that?  Actually I was going for that when I discovered the Distributor cap.  What would you suggest?

Thanks,

Frank

ANSWER: Hi Frank,
I would check the egr valve to see that it isn't sticking slightly ajar. It is located in a pipe that branches off the front exhaust manifold and is routed to the throttle body area. You will find it near the thermostat housing and also that it has a round vacuum operated top, and the valve body is in the pipe itself. Between the two is a flange inside of which there is a rod which is the valve stem. It has a slot into which you can insert a screwdriver tip and then move the stem back and forth against spring-action which tries to close it. Made sure it closes to a full stop and that the action is not sticky. You could spray some WD-40 on the valve stem where it enters the body and then work it back and forth to loosen the action. Such an ajar valve will call poor idle/no starts, and the lean mixture resulting could smell "rich" because it won't ignite.
I doubt it is the crank or the cam sensors, which should set fault codes (11 and 54, respectively) and usually are either go or no go, not the missing sort of behavior. That's why I think mixture is your issue. If it won't close tightly let me know and I can give you the instruction for removal/replacement.
Roland

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QUESTION: Hi Roland,

OK you must have missed the fact that I did work on and verify that the EGR Valve was working.  I did go ahead and replace all the plugs.  WOW a lot of the thing have to come off as you know.  But in the process I think I am onto something and I need your expertise to know how to proceed.  When I got everthing hooked up I started the car and it was running a lot smoother...I thought I had it fixed so I was getting ready to button it up and take it for a ride and saw a vacuum hose that I didn't hook up.  It was on the right side of the plenum.  So I hooked it up.  The problem came back so I disconnected it...engine running smooth.  Took it for a drive, engine runs fine, but the braks don't work very well.  So the vaccuum hose must be the power assist for the breaks, I'm guessing because it runs over towards the breaking system and master cylinder.  And I was egnoring it, but the break light is on.  I ignored it because my friend who owns the car said it was from the emergancy break not working.
So where does that vaccuum hose go to and what could block it to cause the engine to ile down and die?  Also the reason why I state it like that is I noticed that if I block the vaccuum connector running into the plennum that will cause the engine to die also.

Thanks,
Frank

Answer
Hi Frank,
If it is a fairly large diameter vacuum hose then I would agree that it goes to the vacuum cannister of the power brake unit. See if you can verify that.
Usually you would imagine that the disconnecting of a vacuum hose would thin the mixture, however, the system does have the ability to adjust the mixture based on the oxygen sensor readings. So that is probably what is happening.
I don't know why it would not readjust when you hook up the vacuum hose, it should if anything work better I would think.
Have you tried reading out the fault codes with an OBD-II reader attached to the underdash plug? That might be the best way to find out what is going on.
Roland

Hi Frank,
I was thinging about your problem some more. If the engine runs OK with the vacuum line open, then it would seem as though you are running rich. Have you tried cleaning out the throttle body throat, butterfly valve plate (both sides), and the idle air by-pass passageway? You may not be getting any idle air thru the by-pass passageway is my thought.
Roland