R50 (2002 LE) Clogged cat and ignition coil replacement, among other things

[csprinkle]

Hi all,

Hang with me here as this is going to get a little wordy. I got a hand-me-down 2002 LE pathfinder from my dad and lets just say it has a couple problems . I'm not entirely sure what specific issues there are with it but my dad took it to the mechanic a while back and they said that there may be an issue with one of the ignition coils in the engine(?) and that it would be somewhere in the back side of the engine so it would be hard to reach/replace. The pathfinder still drives fine but its a little rough and when its idling, it sort of "chugs" in the sense that you can feel the inconsistency of vibrations in the seat as well as hearing the engine noise inconsistency (I don't really know how to describe it, sorry). They also mentioned that the catalytic converter may be clogged, potentially making the ride choppier and preventing full acceleration. Since I live in WA state, I could technically just straight-pipe the car but I have no idea how to do that so I'd have to bring it in to a shop, and I'm not sure if they'd even do that for me. I think we have one of those readout displays you plug into the dash to diagnose problems, but last time we scanned the pathfinder, I think it said something about ignition coil #4 being faulty so my dad went in and replaced it but the readout still kept the same error on re-scan. Ignition coils #1 and #3 have also been replaced recently by my dad, but he also said that the spark plugs should be replaced (not sure what effect that would have). I have asked a friend of mine who repairs cars and he said that there's a common problem of the cylinder leaking pressure (?) which I am unable to validate as true or not but I figured it could be a possibility with my car. Anyways, I've basically just been handed this car with quite a few quirks to it and I don't want to spend so much money to the point where I could have just bought a used car instead, so I'm looking for a bit of help and/or guidance on what to do 

 

TL;DR - Catalytic converter clogged (diagnosed by mechanic), trying to replace ignition coil #4, and a couple other issues worth mentioning that I am not able to fully describe in-depth

 

Thanks,

csprinkle

 

p.s. I apologize if I am not using common car vocabulary to describe these issues as I am no car expert myself 

[Slartibartfast]

 

 

If it's not throwing catalyst efficiency codes, I wouldn't worry about the cats for now. I wouldn't expect a clogged cat to cause a misfire on one cylinder only. I would however expect the misfire to damage the cats eventually.

 

New plugs might clear it up. They wear over time, and foul if the mixture is too rich. If that doesn't do it, try swapping the coil on the misfiring cylinder with one of the others to see if the fault follows the coil (says the coil is bad), or stays where it is (says something else on that cylinder is bad--either compression or fuel). Fuel could be an injector. The color of the old spark plug may tell you what's going on here--white is lean, black is rich. You can buy or borrow a compression tester that screws in place of the spark plug to see if that cylinder is down on compression. The service manual should have a target pressure and a maximum % allowable difference between cylinders.

 

Download the service manual here and have a look at the EC section. It should have a list of things to check to resolve your code. It assumes you've got the special Consult scan tool the dealers had, but there's usually a workaround. 

[csprinkle]

Thanks for the detailed reply! Sorry that I'm just getting around to reading this now, had a pretty busy week. I'll try what you suggested when I have a free weekend and I'll update the thread when I've done so. Again, thank you for the suggestions, because otherwise I'd be completely clueless on what to do