borka

iTrader: (6)

My SES light is on with a P0171 code, which means Bank 1 Lean conditions.

(2001 SE 5speed)

My car drives fine, idles fine, i get about 20-21mpg highway. now the problem is that it doesnt pool as strong as it should after 3500rpm, it feels like there is a slight dead spot at 3500rpm and after that it doesnt pull as hard as it should, and i also think i should be getting better gas mileage like 23-25mpg.

I did a fair bit of searching on this forum and the big org, and it mostly points to a failing MAF. but if the MAF was bad, then wouldnt it also throw a P0172 code for Bank2 ? i would think then both banks would scream LEAN as the MAF provides readings for both.

Now my question is, how do i actually diagnose or test the MAF? i mean before i start ordering $100 sensors and other things.

how do i diagnose the MAF, or my fuel injectors to see if they provide enough fuel?

so far i tried putting ATP fuel injector cleaner in the tank, ran the whole tank, reset the code, and the code came back after 50 miles. so its probably not a clogged injector.

please chime in if any one had a similar code on their max.

oldngivout

iTrader: (8)

Yes, logic would say this, but not always true.

I fixed a couple of cars with P0171 codes due to MAF failures. It's kinda like the coil issue we have on these cars: so many documented failures say it is better to go ahead and replace with new parts. And don't forget, these are updated parts as well.

borka

iTrader: (6)

Thanks, ill probably end up replacing the MAF, but i wanted to know how to actually test it.
I read somewhere what people test Trim levels and the actual readouts from the MAF, but im not sure how to?

oldngivout

iTrader: (8)

Honestly, I don't know. I never checked into it.

But I can tell you this: many electrical parts only exhibit problems under electrical load and/or heat & operating stress. Those conditions are usually impossible to reproduce on the bench, or even in the car. So we are talking about a known failure prone part that costs less than $100, that you can install yourself in about 10 minutes. Time is indeed money.

borka

iTrader: (6)

ok, last night i borrowed my friends OBDII usb adapter and software, hooked it up to the computer and found that the long Trim levels are hovering somewhere in the +33% which means that the engine is massively compinsating with extra gas. I have also looked at the readouts of the MAF, I opened a graph and took the car for a 20 minute drive. The readings at idle were 0.3-0.7 and at load ranged from 1.2 - 2.5 and under heavy load, high rpm 70% gas pedal pressed, only went up as high as 8.

Per the FSM the normal idel readings should be 2 - 8 and at 2500rpm 8 - 20. so my maf is WAY out of spec, at at like 5000rpm it only peaked at 8.

I've ordered a new MAF and Air filter last night, for $98.

I will report once i put it in.

jer28

iTrader: (1)

I went through this last week....

I checked for any vacuum leaks, put a screwdriver on the 3 bank 2 injectors, and they were working fine. I can't really get to the bank 1 injectors while the car is running. I also tried some fuel system cleaner.

I have 2 new rear O2's with less than 500 miles on them. The 2 upstream are 80K miles old.

My fuel trims are also where yours are, with my mileage being about 21 mpg's. What are examples of good and bad fuel trims for short and long term?

I went with an updated MAS and then I got the ECU reprogrammed at the dealer.

Now I have the P0420 code and I don't know what to change. It could be my 2 upstream O2's, or my cat converter.

Maybe you will have better luck than I did, but if I had to guess the MAS is not your problem.

oldngivout

iTrader: (8)

So..... how did the car run after the MAF change & ECU reprogram?

Usually the performance is unaffected by the P0420 code.

jer28

iTrader: (1)

I guess the performance has not been changed (it's my wife's car). I asked her if she noticed any missing, hesitation, or anything out of the ordinary- and she said no.

So basically all this time the car has seemed to run good, and get about 20-21 mpg's. Never has she complained about the peformance, but it is an automatic, so it doesn't rev too high.

So the MAF change and reprogram did nothing. Except change the CEL from a P0171 system too lean (bank 1), to a P0420 catylst efficiancy below threshold .

tonyw

Take a look at
http://forums.maxima.org/showthread....422&highlight=
and
http://forums.maxima.org/showthread....936&highlight=

I went through this whole thing and posted a detailed write up. Per the Nissan TSB, after you replace the MAF you'll need to have your ECM reflashed is it's not at the latest version. Most dealers will check the ECM version (Nissan uses part numbers for the ECM software version) for little or no cost, but will charge you to reflash it.

jer28

iTrader: (1)

I appreciate the help...I did have the dealer reflash me, after installing a genuine nissan updated MAF (it was a $95 charge for the flash). This has not helped though.

I'm not trying to steal the thread BTW, just add some advice on what I have done for the P0171 code, hopefully it may help???

Jahan

Hey,
Mine is 2000 SE auto. My car has the same problem with the same code. I don't know what to do. Did you get fix your car? Thanks.

borka

iTrader: (6)

I ordered a new MAF and Air filter, i should be getting them this friday, i will try to install it over the weekend. I'll let you know if this helps.

borka

iTrader: (6)

I recieved my new MAF and Air filter on friday, and installed them on saturday morning, changing the MAF was pretty easy, simply unbolt the airbox, pull out the whole airbox and then unbolt the MAF.

My problem seems to be solved, installed new maf, then started the car with no MAF plugged in and let it run for like 1 minute (following and advise i read in another post), then plugged it in, cleared the codes and so far i put 100miles on my car and there are no codes.
I didnt unpdate the ECU, but if other codes appear i might have to.

my long term fuel trim levels returned to normal (-5% to 0%) and car feels much faster now, with a smoother power curve.

fuctkeen

Does a bad MAF produce louder cabin/noise ?

I get the 0171 code once in a while, but it turns off itself after a few days. However, my cabin noise is really loud. It seems like it's coming from the rear, but i don't think it's coming from the windows (leaking wind).

Could it be bad bearings?

annex

Hi everyone!

I just purchased 2000 maxima 5 speed 125k miles. Check engine light was on (along with the abs but i will post that problem iin different thread), I pulled the code, p0171. I cleared it, drove for about 50 miles, then new code came in. It's now p0180- fuel temperature sensor a circuit. I cleared this one as well. My volkswagen was doing the same thing before, it would give me a different code/s every time CEL came on, it turned out to be MAF. From reading this and few other posts it seems to me that maxima's have a similar problem? Should I wait and see what code comes in next or go for a new maf?

thanx!

paulreagan

Thanks everyone for your posts. I am showing a P0171 code on my 2000 Maxima with 66,000 miles. Both 02 sensors have been replaced previously. I will order (does it need to be the dealer) an MAF based on the discussion in this blog. Will let everyone know what it turns out to be. My question is: Where should I get the MAF from?

irish44j

iTrader: (38)

^^to everyone above.

there are 30 threads in the 5th gen forum with "p0171" in the title. Do a search, do some reading.

there are probably 500 threads with MAF in the title. Do a search, do some reading.