Got it. So I am going to replace plugs tomorrow. If that doesn’t work I will replace the wires. If that doesn’t work, I will push it out in the driveway and light it on fire. 😜

 

PM me first

 

I don't like throwing new parts at a problem because new parts are not always good. I like swapping known good for questionable. So move plugs left to right, wires, coils, injectors. Plugs basically last forever at this point with modern high voltage electronic ignition. That said I have encountered occasional plug issues. Given this all started with the coil change that is what my money is on.

 

Yep, this is a tricky one. Since all four cylinders on bank 2 are misfiring, we should focus on what is shared between them. Maybe a ground connection or wiring connector. Like Extinct noted above, probably not four bad spark plugs.

Does the D2 use four shared coils (like my 96 D1 wasted spark arrangement) or eight individual? If only 4 coils, then a coil circuit problem would likely be affecting bank 1 as well.

I guess it isn't impossible for super lean fuel trim on bank 2 to cause misfires. Each bank is trimmed individually, as I understand. That might track back to the O2 sensor. The key mentioned above is to use known good parts and go through a process of elimination of possible causes. Since your bank 2 sensor was acting up when it was in bank 1, I would probably change it out, or swap it again (swapping is less expensive).

Don't give up and use the nuclear option. You're almost there!

 

D2 uses two coils, not four or eight. Each coil fires cylinders on both banks, so issues with an entire side of the engine is a contraindicator to the coils being the problem.

 

Except that is the last thing he touched.

 

Hey Extinct - It did not start with coil change. I had misfires going back to December. I replaced the coils as the last step to try and resolve them. Here is the original thread: https://landroverforums.com/forum/di...51/#post803658

Before I replaced the coils, I pulled the plugs, cleaned them, regapped them and tested them. So its possible (although unlikely) that I messed up the gap.

I know that there is a general understanding that O2 sensors don't have anything to do with misfires, but the O2 sensor was a problem on the driver side. All I did is move it to the passenger side and although the voltage looks better, I am concerned that I really didn't do anything to fix it. So that's why I wanted to replace it.

 

I'll go on record as saying that I think you had a bad connection to an O2 sensor which was corrected when you swapped sides. Those plugs are notoriously tough to get a visual on and a partially connected sensor is a pretty easy scenario to end up in. An actual bad sensor would not dither the way you saw in the second round of graphing. A faulty sensor with a flakey internal connection could be on again off again but that's not usually how they fail. If you want to throw your laptop at it instead of more wrenches for the time being, clear your misfire codes, graph your AFRs for a longer drive and see what they look like if/when you get the misfires. Do you feel these misfires or are they only showing up as codes? This is definitely a generalized problem across an entire bank so I think you can rule out a headgasket (gulp), and while an O2 sensor would affect a whole bank, it would have to show up in the graphing. Good luck, really interested in the answer here.

 

Hey Ahab - I can feel the misfires but only during idle. During regular driving they are not apparent and the rover has plenty of power and acceleration. If I was not heading out on a 5000 mile trip across county to Moab, I probably would just ignore them because they are more of an annoyance than anything else. I just wanted to make sure it was healthy before I headed out.

I never did clear any codes after replacing the coils. I figured they had been cleared by the battery being disconnected but I will do that to be sure.

will graph the LTFTs and report back what I find.

 

Yeah, 5000 is a lot of miles!! I'd want to know too. Your "only at idle" statement could be a clue. Vacuum is always high at idle because the throttle plate is closed and a small vacuum leak could have more effect. There's not as much fuel being added at idle either so the combination can result in fueling inconsistences that could cause a misfire and the CKPS will detect it. Because the system is constantly richening and leaning the mixture you wouldn't necessarily see a misfire manifest itself in the AFRs. You can spray come starter fluid or carb cleaner around the intake manifold and see if the revs jump, specifically on the passenger side since this is where the misfires are. Again, all four is almost a smoking gun for a coil. Clearing them is a necessity before you do more testing.