sba926

2000 Nissan Maxima 5th gen.

Last night I put gas in, and about 5 to 10 miles later car started running real rough with no power. "CEL" was on from cat codes for a long time, then started flashing last night. Seems like Cat Coverter got real hot. I put sea foam (I think that is the name) in tank for water just incase it was bad gas. Car runs so rough I can't burn the gas thru before its seems to get cat hot. I check exhaust pipe end where it has two pipes in one exhaust exit. good airflow one side but not other. (sure bank one is clogged need to replace it) So I changed all plugs with no differance. Checked codes and p0420 and p0300 where there. After reading some post here for hrs. seems like this a pretty common problem. NO REAL ANSWER to what the fix is. I would think if this is such a problem the answer would be easy to find. Post all say it could be many things no one has posted the fix that i can find? I still don't have the right answers to my questions?

My questions are:

p0300 codes: Random Multiple Misfire
With car running so rough can I still test coil packs by removing the wire plugs from coil pack?
just replace all?
Is hatachi OME?
Whats the right part #
Where can I buy them?
Change camshaft posion sensor?

p0420 codes: Below Threshold bank 1
Is this the one up by firewall?
do I need to replace? After i fix the misfire?
I'm sure I will need to replace it!!
Can a bad cat. make misfire?
Is there a way around the cats?

All other codes checked ok, but these, not sure what they mean?
Enhanced DTC found
Catalyst mon - inc
Evap system mon - inc
Oxygen sensor mon - inc
Oxygen sensor HTR - inc < inc> is where scanner says ok on all others
What does inc mean?

Thanks for any help you can give me.
Skip

maxiiiboy

P0300 indicates "multiple cylinder misfire". If the CEL light flashes, then it indicates that the misfire is so bad it may damage your CATs. It seems that's what has happened .....

So, you now have two problems: 1) Misfire - because of bad coil(s) or other reasons, and b) A damaged CAT. It looks like it's Bank 1 (the one by the firewall) where most of the damage is.

This is a good example why it's a bad idea to ignore the CEL light - it comes on for a good reason.

Where to buy parts? Check out RockAuto.com; for OEM parts, go to Courtesyparts.com (you may want to buy OEM coils - most people here would recommend you do that).

dfj240

iTrader: (1)

I have had an extensive, painstaking, experience with the P0300 code. I replaced nearly everything on the car that could possibly be related to that code with no luck. Coils, plugs, injectors, MAFS, throttle assembly, accelerator pedal, fuel pump, fuel filter, crank sensor, both cam sensors, and on and on and on, it's all brand new, and didn't fix the problem. Turned out both precats were clogged. Badly.

The precats are a bit daunting and/or expensive, which is why I, foolishly, put off replacing them or gutting them. Don't do the same! Take care of those precats before they end up requiring you to replace the engine itself.

If you gut them, just get anti foulers for the o2 sensors to avoid a CEL for them. I recommend gutting them so that you don't come back around to the same issue later on.

dfj240

iTrader: (1)

Also of note, and to answer a question you asked, Hitachi is the OEM supplier for the Coils, cam sensors, crank sensor, and several other electric parts. Denso is the OEM for the fuel pump. NGK for plugs.

D.Stillwell

You have a misfire, test the coils and replace as needed. Buy OEM only, dealership.

Your test result from the scanner that says <inc> is for all the emissions stuff, and it means "monitoring incomplete".

Pre-cats are more of an issue on the 5.5gens due to oil burning, not so much on the 5th gen. Take the damn things off and just inspect them, easy to find out if yours are bad or not.

ManualMaxima

iTrader: (10)

Just another solid recommendation to the previous posts, all good advise! Get your cats in working order first (by whatever means necessary), then move on to the leftovers!

sba926

Thanks for yor help guys!

Yes after talking to a few people today they say to start with gutting pre cats to see if that clears up the misfire. After thinking back to my other car cat went bad a car was running rough. Was told to punch hole in it with screw driver so I did and everything cleared up. Misfire could be coming from back presure? B4 I spend a bunch of money for no reason. I know the cat is a goner so i'm going replace it any way.

Dam DFJ240 that sux bud, at least you wont be stuck on the side of the road

What is a ANTI FOULER?

I will post tomorrow with results! Fingers crossed!


Thanks Again