Soldat

Hey guys.

I am about to pull the plugs out one by one to look for any soot or carbon built up which would indicate a rich running condition. A rich running condition in only one of a few of the cylinders would indicate a leaking injector giving too much fuel correct?

Soot or carbon on all spark plugs would indicate a sensor problem correct?

Is there anything wrong with my logic?

Tural

you'll probably see them in all six. i don't think it will be the indication of rich running conditions. look at my pics if you get a chance. you'll see what the inside of a good running manifold will most likely contain.

Soldat

Thanks,

Ended up taking them all out, and they were all perfectly fine.

I am confused now, I have heavy soot in the tail pipe and around the outside end, but the plugs were all clean as could be.

Bad mpg still. Any chance the computer is bad on this? A glitch perhapes?

Anyways, put a whole can of seafoam and filled up all the way. I am going to take it as easy as possible for this tank.

djb383

I wouldn't worry about a 10 year old sooty tailpipe.......If there's no CEL, no codes and the plugs look good, just put fresh ones in and continue on with your maintenance.

gonridnu

U might want to start looking the direction of your Catalytic convertor. Poor MPG and sooty exhaust can be signs of a tired one. Any other symptoms, like poor acceleration or "stinky" exhaust?

rainman

The oxegen sensors don't last for ever either. I think it is at 90,000 miles (somewhere around there) you should be looking at changing them.

Ninja Falco

I m with this guy ^ Oxygen sensor.

4.3L XJ

O2 sensor. They wear out and make it run rich before the CEL goes on

Soldat

Crap, I forgot to mention because I have in many other threads. Sorry about that.

What I forgot to mention is that everything has been checked and replaced that may possibly interfere with mileage.

Cat is new, O2 sensors both new, tailpipe is new as of last fall. And many other things.

The only thing left is the main computer and the fuel filter.

Soldat

And also, does anyone know how much it costs to have a chryslter dealership hook it up to their computers and see if the computer is bad?

Willys55

If the computor was bad you would be having it towed somewhere. Try looking at the coolant temp sensor, many times they go out of calibration and send incorrect info to the ecm/pcm which ends up riching up the fuel mixture. The only way to verify is with a scanner. You need to look and the long term fuel trim numbers as well as the coolant temp sensor signal when engine is 8 hours cold. Always try not to replace parts until the thing is "fixed" you will always go broke before the problem is solved.

Soldat

Good advice. Thank you!

Ok so no computer glitch, the CTS I feel is not bad. Here is why. I have had it hooked up to a scanner and it read 208, which is pretty much what anyone would guess by looking at my temp guage. Never had any type of overheating problems either.

What does the 8 hours cold do?

I forgot, the place I went to couldn't check the fuel trim because they didn't have the correct scanner for that chrystler vehicles. They all expressed their anger toward who was in charge for that.

Ok, I just researched fuel trim, and you're correct. However in my quick reading what would the long term adjustments tell me? A sensor is bad?