Ok so I finally got my muffler fixed. SES light is still on. Not only that... My maxima is incredibly slow... I pulled the code and its P0171. Planning to get my Fuel injectors changed and MAF sensor replaced. Can someone tell me how much these two would cost taken to the shop/done at home and you've gotten these replaced how much did it effect the overall performance of the car. My car barely beat a Rav-4... I need a miracle right now...

 

I'm not sure what those codes are, but throwing parts at a car is a bad way to go..I'm not sure how much injectors are, but before spending that much money I'd be dam sure to do a injector balance test first. (or get it done somewhere if tools unavail.)

EDIT: not to mention bad injectors can be the cause of another problem.
I.E. poor fuel filter and crap in the tank......If swapping injectors swapping fuel filter isn't a bad idea. Though I find it hard to beleive you have 6 sticking/bad injectors.

 

How do I do a Injector balance? *Still a newb in highschool*

P0171 - P0172
1)If bank one and two codes set together suspect fuel pressure MAF sensor
2)Oxygen sensor defective
3)Ignition misfire or vacuum Leak repair
4)fuel injector problem
5)Refer to AZ commercial Preferred customer.

 

i have seen alot of 0171 cured by a new maf but thats not to say that is your issue. you saying the performance is crappy would be in line with a maf on the way out. i doubt your injectors are bad simply because many people do not have issues with them. your 2k probably has the outdated maf where the actual wire sits at the bottom of the housing. the new maf put the wire up higher in the housing to help keep debris, oil etc from making contact with it. i would suggest the maf first and it can be replaced in a matter of moments. push the connector in and remove the harness. use a security torx bit (25 i think) on 2 then wedge it out and replace.

 

MAF replacement write up? Searched and cant find one, thanks.

 

I'm not sure how to do it at home, a shop usually needs to do it. Probably would charge you an hour time with results provided. I wouldn't start there though.
I went ahead and looked up the codes.
p0171 is fuel system lean bank1
p0172 is fuel system lean bank2
Buying a scantool is a good idea if you're going to try to diagnose problems like these yourself, that way you can check to see what your long term fuel trim (LTFT) short term fuel trim(STFT), etc is. You can also check your MAF readings straight thru your scantool with the enhanced version to see if it is reading correctly.

You MORE THAN LIKELY have a weak fuel pump, clogged filter, bad pressure regulater valve, or bad MAF.

Your 02's are seeing that the A/F ratio shows to much oxygen, thus adding more fuel (changes STFT which ultimately changes LTFT) Once the engine riches up your A/F ratio so much it sets a code and doesn't make it any richer.... Lets go thru the list

1)If bank one and two codes set together suspect fuel pressure MAF sensor
Most likely one of these two
2)Oxygen sensor defective-
unlikely. Two reasons. 1.)both banks are set. 2.)no p0 code for switching problem.

3)Ignition misfire or vacuum Leak repair. Possible, but unlikely. You would probably notice a loop at idle and/or a p0300 code(randon cylinder misfire)

4)fuel injector problem.
six injectors at once is highly unlikely

If you have a multimeter or can get one. ($4.00 at Harbor freight) you can test your MAF. There is a how to somewhere on the org. Just search for it.

To test your fuel system. Hook a pressure gauge to the schraeder valve on your fuel rail. Fuel Pressure specs are as follows
With Regulator Vacuum Hose Connected 235 kPa (34 psi)
With Regulator Vacuum Hose Disconnected 294 kPa (43 psi)
(If your disconnected is close to 42 and your connected pressure isn;t proportionally close to the same from spec then your regulater is bad)
You can also do a volume test on your fuel system. If your gauge has a hose to drain fluid, dump gas from the schraeder valve into an empty oil bottle for 20 seconds. Should have about 16 ounces in 20 seconds in the bottle.

 

To test maf.
http://forums.maxima.org/showthread.php?t=447467 .
I did this test last year shortly after purchasing my max and made this QUICK write up before I knew how to show pics in the forum.
It's kind of hard to follow I need to redo it, but it's the only write up that I know of.

 

Bad MAF is my vote on whats causeing your problem. Is it real sluggish in third gear like right after it shifts out of second? And how many miles does it have? I had to replace mine at around 60,000.

Are you serious? It's incredibly simple to do. Right after your throttle body, you'll see a tube that had the back part of a sensor sticking out of it. First you have to go to your local dealer and order one, or possibly they'll have one in stock. Go home and disconnect the old and just put the new one in. O, and it's not the sensor part that sticks out of the back, it's the black tube you have to remove as a whole. It's pretty much a common sense job. If you don't know what it looks like, i'm sure somebody has a pic of the bay with it highlighted.

 

Personally i'd get rid fo that big azz box looks like it weights atleast 200lbs +
Second off all your injectors are fine unless you've been using the worst gas possible.
Third replace the maf get in touch with Dave B probably cost you like 80-100 bucks from him.
Fourth look up on the vias problem.
Fifth after you do all that let us know what else is wrong with it

 

Im 91k miles

Ive searched for VIAS info in the past but came up with nothing I know its the Variable.. intake...something something lol... But how would I look into it?