Code P0170 1997 Nissan Maxima GXE

First of all how does one generic code "convert" to another generic code? Neither is a Nissan specific code! Check the forums, those codes are often caused by intake gasket vaccum leaks, MAF's and EGR problems! Secondly po170 is not lean, it's just stating a fuel trim malfunction! po171 would be lean! it could be somewhat rich and throw po170

Therein lies the problem. In my repair manual and on maxima.org forums, the nissan code 0115 refers to a "lean" fuel problem. I was incorrect in saying that it was a p0170, it was a p0171. I read the code straight from the car, not an OBD II scanner. There are conversions for the codes from nissan to generic OBD codes.

HI ¡¡ As Jeff says, p0170 and p0171 are not the same codes.. You told us is actually the P0171 so these code means system too lean in bank 1. So I will recommend you to, first clean the MAF sensor and then check if your oxygen sensor is working properly. Remove the oxygen sensor and check if their wires are ok and check the harness connector for proper voltage supply. Check and clean your injectors, they could be dirty and clugged causing lean condition ¡¡¡¡ For lean conditions could be a lot of possible causes ¡¡ you should start by checking these ¡¡¡¡¡¡

For some reason i get the p0170 and p0171 codes confused. Anyway, I've been researching the forums extensively, I am pretty sure I have an intake leak or a fuel problem. The O2 sensor on the troubled side is very new and has tested fine. I have cleaned the MAF, and run electrical tests on it. I've also checked all the rubber hoses in the emissions cluster below the throttle body. Next is to check every injector which requires me to remove the upper manifold anyway. Since im in there ill do the lower gaskets too. Hopefully one of the part stores around me rents out fuel pressure testers if the gaskets dont work. Thanks for your help!

I may be too late, but If I were you, I'd check fuelpressure before I pulled the intake, etc. If you smell a fuel smell and can't locate a leak, make sure you're evap hoses are all intact and none are leaking. A fuel smell isn't good, but your code refers to a lean condition, which basically means your engine couldn't add enough fuel to correct the lean condition. Start with fuel pressure and post back. Go buy a gauge if you have to, it'll be useful over the years

Im suprised Maxima.org didn't point you to an intake gasket problem!

They rarely reply on things now. Mostly posts about modifying their cars with turbos, coffee can mufflers, the like....

Ok, got a fuel injection pressure tester from NAPA. I went by the testing guidelines written out in the Haynes manual. Here is the "normal" data followed by my data: PSI Ignition ON, engine OFF : 43 psi (stock) PSI Ignition ON, engine OFF: 33 psi (me) PSI while engine on: 34-36 psi (stock) PSI while engine on: 33 (me) They also say to pinch off the vacuum hose that goes to the fuel pressure regulator, the reading should go back up to near 43 PSI. When I did it, no change...... So I test more..... To test the fuel pressure regulator, you are supposed to pinch the return hose and see if the pressure goes above 43 psi, which would indicate a bad FPR. Well, when I pinched the return hose, it shot to about 50 PSI and cut off. If Haynes is right then my FPR is shot. Discover more plugs coil spark plug It goes on with more tests to see if the fuel pump or injectors are going bad, but I would assume you would test these after the regulator checks out. Darkrooms or Compton, what is your take on this? My gut tells me to believe the testing procedure, but then again I'm not ASE certified and my speciality lies in older european cars

HI ¡ Check fuel pressure disconnecting the vacuum hose of the fuel regulator, not only pinch it, is better to disconnected. Are you having vacuum in these hose when disconnecting it ? What is the actual pressure ? What it doesn´t make sense to me is that if you are having more fuel drawn into the engine it should not show the PO171 to lean ¡

I'll disconnect it tomorrow and check for vacuum when its light out. But if you saw the pressure data I gave the car has less pressure that what the factory specs are.

Ok got vacuum and the pressure regulator. Tested the whole thing again this morning and got the same thing. Low pressure when the fuel pump primes, 1 psi out of range when the car is idling, and it stil cuts off and gets a pressure spike when the return line is pinched off. Im following verbatim from my haynes manual

According to your post, the pump sounds okay. DId you check for vacuumleaks? Have you checked thoroughly?

I have checked to the best of my ability with the tools I have. I dont have a mityvac vacuum tester so I cant get a definitive reading. The pump did test out ok according to the manual, but the fuel pressure is lower than what the book states.

Update: Put new fuel pressure regulator on, no engine light, no more hesitation or stumbling. thank god.

he he, hope we helped