Cylinder #2 misfire

[speedgeek]

2003 Liberty 3.7 engine.

I am getting a CEL code cylinder #2 misfire. I swapped coil and plug with another cylinder but the misfire stayed on #2. It is very slight and almost not even noticeable with the hood up. Engine shakes a bit, but just barely. I have never owned a Jeep before this one so I am not sure what normal is.

I bought a scanner and am learning what to do with all the info but I am far from knowing what I am doing with it yet.

One thing that jumped out at me even with my limited knowledge is the fuel %trim values.

Long term bank 1 is 0.78%
Long term bank 2 is -14.06%

The computer evidently thinks bank 2 is too rich and bank 1 is slightly lean.

I also have some mode 06 numbers showing as failed but I have no idea what they are
TID $11
TID $31
TID $51
TID $52
TID $53


and one of the O2 sensor voltages never moved higher than .1v

This was done with a cell phone app and I didn't have the data logging configured, I will drive it around a bit with a lap top connected and get a good range of data this weekend.


Does anyone know what the TID numbers mean? Could a bad O2 sensor cause the misfire?

Compression check is next to eliminate or confirm a mechanical issue, if that checks out good than the hunt begins.

Any ideas?

(Edit a few hours later) the more I think about it, if there is a sticky valve openin before combustion is complete, would that cause the O2 sensor to lean out that fuel bank?

 

[02redKJ]

I was just going to recommend the compression test followed by a leak down test. As for your other questions, I am not qualified to answer them, but I am sure someone more knowledgeable than I, will be along soon to answer that for you. Good luck!

 

[hayleys_c0met]

I'm not sure if you fixed it yet or not, but I'm having a misfire problem too. I'm not having the same exact issue as you are, and you're question is a lot more in depth than mine was, but this afternoon someone gave me a few suggestions. The thread is here (http://www.jeepkj.com/forum/f196/how-do-i-fix-misfire-55766/) if you want to go check it out and see what he said. Sorry I couldn't be much help myself, but maybe his ideas will get you going in the right direction.

 

[the_dealer]

An upstream 02 can cause misfires but is normally multiple cylinders on the same bank. Have you tried to unplug the #2 injector with the engine running and see if there is a change in how it's running. If u think there's a change swap the injector with another cylinder and see if the code moves. Is the motor making strange noises?

I'd go pick up some Red line SI-1 fuel system cleaner (sold at oreillys). Even if it's not your problem, you can only benefit from using it, but definitely a good starting point. I had a #7 misfire in my heavily modded 98 cobra, and used some as a last resort before buying injectors. I used my laptop and tuning software to monitor the a/f, and o2 readings. I don't believe in mechanics in a can, but the stuff works. In less then 250 miles my a/f was back to normal (well slightly better). I started using it every 5k miles in all my rigs after that. I eventually replaced them (due to needing more fuel for the s/c), and took them to be cleaned and flow matched for resale. They were within 3% from new flow rate, and a +-1.8% between all 8. That was the dealmaker. My 190k mile kj went from 17-22 after one treatment

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