# 1993 Nissan Maxima runs rough, excessive fuel, kinda long



## 93max (Dec 20, 2010)

hi guys , I was hoping for a little nissan geek expertise on my current headache

1993 Nissan Maxima automatic
aprox 95k miles

compression test good (165 across all 6)
new fuel pressure regulator 
new plugs, wires, cap, rotor, fuel filter 
cleaned MAF (runs with it plugged in, will not idle unplugged, but i can keep it alive with the throttle) 

runs rough, smooths out in upper rpms in neutral or drive, put some new gas in it and it seems to be getting better, but still not gonna pass emissions like this

even after running for about 45 mins with new gas in it its still fouling all 6 plugs with fuel, and the plugs need to be cleaned to get it running again. I put the fuel pressure regulator in it because base fuel pressure was a little out of spec on the high side (45ish psi) and when I crimped the fuel supply line the idle smoothed out considerably 

with the new fuel pressure regulator installed fuel pressure is 36-38psi at idle, and the car is still running super rich and fuel fouling all 6 plugs, theres a couple of questionable vaccume lines here and there, but I doubt they are causing such a super rich condition at idle 

so to end all of this...Does anyone have any ideas on what to check next? I dont know how to pull codes on this car, but there is no check engine light on, this car is supposed to be for a friend of mines little sister and i'm afraid she'll never get it because its gonna be in flames in my backyard soon! please help! any info is appreciated


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## 93max (Dec 20, 2010)

tried a computer out of the parts car as well, no luck...any ideas guys?


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## jdg (Aug 27, 2009)

Almost everything but the O2 sensors


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## 93max (Dec 20, 2010)

the tune up was done prior to me getting my hands on this car, I talked to the previous owner and the mechanic that did the work, they both said the car ran fine before it was parked...I dont know how long it sat for before it fell in my lap...I even tried unplugging the O2 sensor to see if it would make any difference...didn't really do much for it...im gonna try the MAF out of the parts car today just to see if that helps it any

any one else have any ideas? I dont want to throw parts at this car, she can't afford it, I really thought the FPR would have taken care of it, especially after crimping the supply line smoothed out the idle...mind you it only smooths out for a second before it dies from a lack of fuel, a friend of mine had suggested swapping the computers in case the computer was bad and holding the injectors wide open, I've heard of injector issues on these cars, but i have a hard time believing all 6 are bad at the same time...anyway im gonna keep banging my head against the wall on this one, if anyone wants to chime in I'll be checking this throughout the day and I'll post anything else I try and whether or not it makes any difference


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## rogoman (Dec 16, 2004)

All it takes is for one fuel injector to be leaking to cause your problem. While the engine is idling, unplug one fuel injector electrical connector at a time to see if the idle is affected; the one that doesn't change the idle condition may be dead.


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## 93max (Dec 20, 2010)

I realize one injector could cause a problem, and i have unplugged them individually like I did with the spark plug wires and it wasn't conclusive...I need to get a noid(sp?) light from a friend of mine to really "check" them...I just cant see all 6 of them being bad, and its not like one cylinder is getting fuel fouled...all 6 are, all 6 plugs have exactly the same super rich condition...I still haven't tried the MAF from the parts car, I'll do that today and report back


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## jdg (Aug 27, 2009)

Any exhaust leaks?
A leak before the front O2 sensor will screw up the readings from it.
Same thing with an intake/vacuum leak, except it'll screw with the MAF and/or MAP readings.


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## Tf0r1 (Jun 20, 2005)

Id bet its a bad fuel injector or several bad injectors.

My budy saw this post and said the same thing Bad injectors or bad intake gasket (Leaking intake manifold)


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