Please help

So I've been having some issues with a Random Multiple Misfire (PO300) for about a year now and no other codes. My check engine light has been solid for quite some time now but recently been flashing here and there with a bad engine shake. My car would get real rough and then it would stall occasionally. Today I went to let it warm up and the hotter it got the more knocking sound came from the lower part of engine while smoke was also coming out of the exhaust. It smells really bad too. I took it for a spin and the knocking was pretty bad, the car was lacking power and it stalled. I was able to restart it with no problem and drive it to my parking spot.

Should I get all new OEM coils? Could my CAT be failing and causing this horrible sound?

I've changed:
both valve covers to the 6th gen
fairly new OEM spark plugs
Swaped a few used COILS here and there in the front.
Seafoamed the whole engine and gas
Cleaned MAF
new battery

 

If you have a multiple misfire and the codes for it, you should replace your coul packs with new and updated OEM coils.. I would think if it had anything to do with your cats you would have secondary 02 codes as well, you answered this question on your own.....lol

 

^^^ agreed. The P0300 is an ignition problem and the flashing check engine light is also an ignition problem. Until you you get all the cylinders firing, don't even think of doing anything else.

 

This...

I'd also like to add that the flashing SES light usually means that a coil pack has died, which is why it runs the way it does.

OP, scan again and you should get a secondary code telling you which coil pack it is, and get nothing but OEM.

 

So I guess just fork out the $500+ dolla and get all 6 oem coils since there arn't other codes? Holy ****, lol

 

Read my above post

 

Thanks, I read your post.. I don't have an ODB meter, I was thinking about getting a little $50 one since I don't want to drive my to Autozone to get a free scan.

 

I bought an Actron scanner for around $100, but as long as it gives you your codes it will work, which it should. It's always a good idea to have an OBD scanner if you own an older car out of warranty if you are going to work on it, or you can take it somewhere and pay for someone else to do it.

It's up to you if you want to replace all 6 coils or just the one that failed.

 

If you have a smart phone you can always pick up a bluetooth adapter and use Dash Command or Torque. I have both and they are great apps.

 

ok, so I just went out and bought an OBD scanner from wal-mart and hooked it up when I got home.. The only code I still have is PO300 (random multiple misfire). I can't believe it won't throw any other codes.

I started the car again after the scan and the warmer the car got the louder the knocking sound. The idle was rough.

 

Pull one coil at a time while idling. See which coil does NOT make the idle worse. Replace that coil. Since you have a 2002 this only works on the front three. But at least you don't have to just go buy 6 coils!

 

Yeah I did that and was able to unplug 5 of them with the engine running. Each of the 5 coils made the car idle worse when disconnected one at a time. I've read that way of testing is completely accurate since a coil can still be bad even if it throws a rough idle when disconnected. Well, looks like I may just get all 6, boy I'll be so pissed if this doesn't fix the problem. wish me luck lol $500 later

Believe me I've tried nearly everything to narrow down this problem and yet still no solution.

 

Do you have a 5-cyl Maxima? :-) The one which does NOT make it run worse is the culprit. Replace that first.

Now that you have the scanner, just leave it connected. Every time you start the car, check the codes (don't forget the pending codes too). Eventually, you will get the cylinder specific code.

However, coil disconnect test when the car is running bad is the easiest and simplest to do. If all 6 coil removal cause your engine to run worse, then you have major engine trouble!

 

Yep, I did that 2 years ago on my car, I paid close to $600 for all coils and plugs from DaveB back then... It was the single most expensive tune up I have ever done in my life so far, but It is worth every penny, the day after I replaced the coils I took the in laws on a 3500mile trip without a single issue or a ses light... if you want that car to run nice and smooth get the oem gray dot coils and move on with your life... trust me, the previous owner gave me 12 extra oem non gray dot when I purchased the car from him and I was messing around for 3 months with the P0300 and multiple bad coil codes, if figured I will find a good coil in the mix but they all worked for a week or so...

 

Don't be so sure! I had this problem from the moment I got my 02 SE 6-Speed. Nothing but a P0300 code, no O2 codes or anything else. Replaced all coils, MAF, Throttle Assembly, and on and on and on. When it was all said and done, I spent over $3k in parts with no luck whatsoever. Final verdict on the problem: Clogged Pre-Cats. Easy to diagnose too; all you need is a vacuum gauge.

Make sure the engine is cold
Plug the vacuum gauge into one of the vacuum lines on the intake manifold
Take note of the gauge reading in hg/in
Let the car idle until the engine gets to normal operating temperature
Take note of the gauge reading again
If the reading has increased then you have some kind of clog. If it has increased by about 0.5 but less than 1 hg/in than you have a very minor clog. If it has increased by between 1 and 1.8 hg/in or so, you have a fairly moderate clog. If it has increased by about 2 hg/in or more than you have a very substantial clog.

If it doesn't increase at all, then look elsewhere, but don't rule out an exhaust clog or a failing cat just because you don't have an O2 code. I did, and that ended up costing me over 3 grand.

-Nathan

 

Pull the dipstick and check the level and condition of the oil. I think you may have spun a bearing

 

So I had a friend mechanic from Nissan that came over to check the problem.. Turns out one of my piston rings is shot, creating this griding and rattle sound. When I throttle the engine it dumps burning oil out the exhaust while this loud noise occurs from the engine. He said that the ring is just moving around in its spot and oil burns right through.

I called a couple of salvage yards and they want $1500 for a used engine with 90k. Is that reasonable?

I allready know all this man, I've done it a million times.. I was able to reach and unplug 5 coil connectors to see the difference.

 

I have been burning oil for over a year now but I've always topped it off promptly.

 

do you ever redline it? perhaps miss a shift and over rev the beast?? if so id say a spun bearing as well...a piston ring is possible but id do a compression test to confirm.