Chrysler Repair: 2,5 V-6 rough idle, rapidly varying oxygen sensor, fuel air mixture, egr solenoid

Question
QUESTION: Hey roland.

 Ok this is what its all coming down to and hopefully we can find a fix. I only had the car in idle until yesterday. I had to put together my radiator (had to replace it had a leak). And This is what happens. With the EGR Solenoid connector off, it runs perfect in idle, no backfire, and no catalytic egg smell, it just runs fine, however when you put some load on the engine, it starts to backfire again and runs rough (Even very little load, just being in gear with breaks on) When you accelerate it seems fine, but you get smoke from the catalytic and it smells.

 When the EGR connector is on, it acts the same way just idle's rough and the EGR does not open.

 I am still not getting any engine light codes, and I do have a computer to read time advance and O2 Sensors, and all the other sensors. The only thing I find funny and do not know if it is normal is one of my o2 Sensors goes from .2-.8 rather quickly (ever second it changes) as well as my time advance goes from -.2- 15, both going back and forth every second. Is there a guide sheet that tells you what these sensors should be reading in idle?

 I think the prob. is related to the fuel/air mixture, I have already replaced the IAT and the MAP sensor and no results. If you get any ideas let me know!

ANSWER: Hi Ian,
Is the widely varying oxygen sensor on the same bank of cylinders where you had the valve rocker break earlier? I wonder if there is still something mechanical wrong on that side of the engine, if that is the case. If the problem is on the accessible side, then maybe a compression test of those three cylinders would be worth doing. Its more work if it is the back side, as you already know.
The voltage range of the sensor is from 0.1 to 1.0 (lean to rich) and ideally it should be around 0.5v.
Roland

---------- FOLLOW-UP ----------

QUESTION: Hey roland,

 I am sorry for the slow reply I had to do some work on my pool before it got to bad. I did do a compression check and the compression was the same before I took apart the car, it was 220 on the #1 cylinder, and 220-230 on all the rest. I think a little carbon buildup is in them, factory spec I think is 215, but overall perfect compression. But, yes, I did think the same as you did, but the compression check said otherwise.

 Also, taking out the spark plugs in any cylinder shows signs of bad fuel mixture, I believe to lean. Could it be possible that I ruined one of my O2 Sensors in the process of trying to start the car 80 or so times before it started? And should it be bouncing back and forth like it is? The other sensor is reading steady. if you need more specific information I can right down what all the sensors are saying.

ANSWER: Hi Ian
I doubt that the sensor is bad, and it seems to track with the other mixture-related (possibly) mal-functions. I don't have a set of sensor values to compare to for that engine. I did 'note' what they are for my '89 cyl engine but they may not be relevant for the V-6.
I am amazed that you can describe the way it runs and still have no codes. Are you getting corroboration that the code reader is connecting to the PCM? Have you ever seen codes since this all began other than the 0108?
Roland

---------- FOLLOW-UP ----------

QUESTION: I feel the same as you. I have even disconnect a few random things and have ran the car for a few second to see if a code pops, and it does. And I checked what protocol it is communicating with and it is a accepted protocol for that car.

I keep trying to think back at what I touched that could of caused this, and I KNOW (along with tests that prove) that, that rocker arm should be on right. It driving me nuts that a code is not showing up, it must be because something is working just not good enough, and not bad enough to make the computer show a code. I am really at my wits end.

 Is there a couple of tests you can give me to check out? I am happy with testing, I could do it myself but I have no documentation on what the volts should be and what the sensors should be saying.

  I think what ever it is, It should be directly related to that EGR valve solenoid control. The computer for SOME reason is making sure the EGR does not turn on. What could cause that?

Answer
Hi Ian,
Did you verify the wires to the solenoid? And that the vacuum is connected and present? Have you tried checking for whether the solenoid is being evergized by looking at the voltage on the gray/yellow wire.
Has the engine warmed up when you check it out as it could be that the egr won't be brought into play unless the engine is warmed; I not sure about that point.
Maybe there is a bad injector that is either not pulsing the fuel, or not shutting off? All the plugs look lean, you said, with no differences. Tried pulling the spark plugs one at a time  to see if one has no effect on the rought idle, implying there is an issue with the spark or fuel to that cylinder?
Roland