Hey Guys,

First time poster here, and im going to apologize in advance for the long winded post! I have a 2004 Maxima 3.5 5 speed auto with almost 200k. Bought the car last year for my fiance and have nothing but bad luck with it since. The first week I had it, the radiator exploded. No big deal replaced that. The next week the alternator started acting funny, car would randomly charge then not charge, die randomly etc. replaced alt, car did fine for a couple weeks. Woman was driving the car through town one day, and it just died in the middle of the road with no warning and would not start back

I let the car sit for awhile out of frustration with it, I was pretty confident the ecu went down in it but wasn’t sure. Finally I took the car to the local Nissan dealer paid them 100 bucks to diagnose it, and they confirmed that the ecu in fast was junk. Bought an ecu from a reputable junk yard that said it came out of a running car that was totaled in the rear end. Plugged ecu up, took car back to Nissan, paid them another 100 bucks to flash the ecu to the car. Car would start and half *** idle then die, if you try to put it in gear it dies. Im 99.99999999% sure the 3 cylinders closest to the firewall are not running.

Since I brought it back, it smelled like bad gas so I drained the tank, and filled it up with fresh gas, changed the plugs as they looked like the original and had no electrode left. (Another reason I think the back 3 are dead is bc they were wet with raw fuel) Changed the front three plugs first, it idled slightly better but still nowhere like what its supposed to ber. Pulled intake off, changed back three, no real difference there.

It sounded like it was having trouble getting exhaust out so I thought maybe rats made a nest or something in the piping/mufflers, so I cut the exhaust off rught before the cat under the car. When I did this I noticed that it looked like the cat was stopped up really bad with stuff that had came into it. So I started looking around, and the pre-cat on the front bank of cylinders was fiery hot after only dling a couple minutes, and the cat for the rear bank of cylinders was air temp. (another reason I think the rear bank of cylinders are not operating.) Im assuming the front pre-cat is the one throwing crud into the rear cat. So as a temporary thing to check I busted out the junk in the front pre-cat, looked like every other stopped up cat ive ever seen (will get another one if I ever get this thing running right) Started car back up, same old same old, motor shakes like hell barely runs for a bit and dies.

Checked the intake to make sure mice didn’t get in there, everything looks good, pulled codes, only code available is still a p0300 multiple misfire, same thing as when it came back from having the ecu flashed. Im at my witts end with this car, its been almost a year, and my woman hasn’t been able to use this car (which means shes been driving my truck and beating it to pieces for a year!!!)

Thank yall so very much in advance for your alls help, I wont be near the car till Saturday, but I can have my buddy try anything yall recommend, I have access where we work to a snap-on solus diagnostic machine too if anyone needs any kind of data from it.

Thanks so much in advance for any and all help,
Evan

 

Start here:

http://www.nicoclub.com/FSM/Maxima/2005_Maxima/ec.pdf

Begin on page 286 (of 700+) and it walks you through diagnosing P0300.

I would add, if my radiator blew out, I'd be looking really closely at the color and amount of coolant and oil thinking maybe you have a blown head gasket. A red hot cat could be sucking umetered air going super lean and hot, or it could be a misfire dumping raw fuel into the cat which lights off there.

Use unlit propane torch around the intake manifold and hoses, brake booster, move all vacuum hoses around and listen for a change in idle. If it idles up, then you found a leak.