OK... the answer is in!!!!
The new MAF sensor arrived ($83 plus shipping from Southpoint Nissan)... Took 10minutes to install (I installed the entire sensor, I did not try to save a few minutes by swapping out just the element as some folks have done, there was a note inside the package that specifically said to replace the entire sensor, it said you cannot just swap the elements... I wonder why, the housings looked exactly the same).

The airflow readings with the MAF sensors are about 50% to 200% higher than the old sensor (the biggest difference between the new and old sensor occurs at the higher RPMs, 2500+).

I reset the long term fuel trims and have since put 180 miles on the car over three trips. The long term trims for both bank 1 and 2 have gone from +33% to apx -10%. The short term trims are now near zero most of the time and never go much above or below +/-5% (this tells me that the system has completed adjusting to the new sensor).

Summary diagnosis... the MAF sensor was failing "soft"... i.e. it was improperly reading low, but it not low enough to throw a MAF code. This caused the fuel trims to run high throwing the 0171 (and an occasional 0174 code).

 

howdy, during the past 3 years i had my 2k maxima (88kmiles), the check engine light never went on. recently it started to have the idling problem like many others did and even automatically shut it down in morning starts. but after my re-turning the keys, it ran fine.

i took it to a local smalll garage and paid 60 bucks--the guys there tightened the air intake hose and cleaned throttle body (still don't totally understand but this is what they wrote on receipt). after that the check engine light went on with the code P0171. i took it there again 2 days later--they said that they had no idea what that was and turned the light off.

1 week later the light turned on again and i finally brought it to the nissan dealer. i paid around 100 bucks for inspection and i was told that i will have to pay around another 730 bucks to fix these. (see below for details)

I spent a whole afternoon reading the threads in the forum and it seemed that many folks have got this problem too but they fixed the AFM themselves--but they then still get the code or the O2 sensor-related check engine light. besides, it seems that only nissan dealers are able to do the programming thing with ECM.

Ok, my question is: do you guys think this is a reasonable charge? can i buy the parts and have them installed at a cheaper place but then ask them to re-program it? or, if i don't fix that, will that cause some more serious/expensive problem in the future? anyhow, any suggestions are welcome!

really want my old happy max to come back

this is the price break-down:

air flow meter
reprogram ECM
change air filter
(together these cost around 580 bucks: 112 bucks for AFM and 15 for filter and 450 for labor)
b-1 o/2 sensor
(this costs around 250 bucks: 148 bucks for parts and 100 for labor)

on the examing chart, the data said:

FUEL SYS-B-1: Mode4
FUEL SYS-B-2: Mode4
CAL/LD Value: 41%
Coolant TEmp: 185 F
L-FUEL TRM-B1: 133%
L-FUEL TRM-B2: 133%
S-FUEL TRM-B1: 108%
S-FUEL TRM-B2: 108%
Engine speed: 2200 RPM
Vehicl Speed: 60 mph
ABSOL TH-P/S: 12.6%
B/FUEL SCHDL: 5.0 msec
INT/A TEmp SE: 82 F

 

Did you bother to read the thread? I'm geussing you skipped over post # 41 & 38?

 

i did read the thread but i do hate to see the light come on and off and on...so it took only 10 min to do the labor? what a steal--really hope that i'm in TX *_*

 

Yeah buy a maf and put it in yourself, then find a dealer that charges somewhere close to the typical $80 for the reprogram.

AVRITCH, Welcome to the .org, please become a regular, the 5th gen forum needs more guys like you, and thanks for the follow up, I also like that plastic wrap technique, allthough if the suction isn't there it could be from a cylinder being in the overlap stage, but nonetheless I will use that at some point I'm sure, thanks and again welcome to the .org

 

I'm am currious about the long and short term trim values in your listing from the dealer. I believe from what I've read here and what I see on my scanner that the short term trims max out at +/-25% and that you'll throw a P171 when the long term trims reach 33%. So why yours are 133% and 108% is odd (I think the 1's may be pluses). Or maybe the dealers scanner (the Consult) uses a different scale factor than standard OBD II. (PS. I'm using a scanner from Autera, it's a module that plugs into a standard laptop and allows reading/clearing of codes as well as real-time monitoring and plotting of sensors... and I always threw the P0171 and P0174 when the respective long term trim reached 33%). $450 labor to install an MAF sensor is worst than nuts... it simply highway robery. While slightly handy with a wrench, I'm no mechanic and it took me less than an hour, start to finish, and that included finding the socket set and cleaning up afterward. So your labor cost should have less than 1 hour (~$100) (you remove four or five bolts and loosen a clamp to get the airbox out and then it's a simple four bolts to remove the MAF from the airbox... it's very simple). I'll bet the bulk of the labor was for diagnosis (although they should have broken the costs more clearly for you).

I am still very currious about the need for ECU reprogramming. With the new sensor installed, all the sensors readings are now normal and my MIL has not gone back on.

I'm really wondering if the purpose of the reprogramming is to simply reset the Fuel/Air mixture table back to normal (default) levels. I found through experimentation that if you disconnect the MAF sensor connector and idle the car for 30seconds, the ECU sets the long term trims back to zero. You can then connect the sensor back up, clear the P0100 code that you get from disconnecting the sensor, and the car will, over time, rebuild the table as it learns and adapts to the new sensor. I've got 400 miles on the new sensor and the trims have stabalized very nicely. (PS, when you run with the MAF disconnected, in addition to the MIL you'll also see anti-slip system light go on... that was wierd... however, all went out when the MAF code was reset).

The O2 sensor cost was reasonable for a dealer. I paid 120 for the B1S1 sensor (Bosch) and it took me about 45 minutes to install (it was a little bit of a pain to get to, but not too difficult).

Finally, the one difference between your trouble and mine is that my car always ran "mostly" normal. The only symptoms I had, other than the MIL, was higher than normal gas milage, a very slight/momentary hesitation when acclerating during the first 30seconds after starting, and a slight knocking under heavy load before the car fully warmed up. The slight hesitation went away amost instantly (i.e. before I was out of the driveway), and the knocking went away after 10 minutes of driving. If it wasn't for that pesky light staring me in the face, I probably would never have done anything.

 

Thanks avritch for such detailed and helpful tips! Thank God I did not go to the dealer's and instead, I went to the first garage I went to that cleaned the throttle and stuff and was told that other than ECU reprogramming, I can buy the parts and ask them to install all for me and they will charge around 100 for all labors. Then, hmm, it seems that I am always on a quest for some answers ~~ I went to a realy trustworthy guy around my area and was told not to do anything and bring the car back when the light came up again. well, finally it did come up yesterday when i was on highway with the a/c on, yay I will bring my max to this guy tomorrow morning and listen to what he would suggest.

by the way, the guy said that he could give me a better price by replacing parts (maf and o2 sensor) made by other factories other than nissan--is this a big deal? i know this sounds a little picky but the previous owner has always been to the dealers for replacement and well, is that true that nissan parts will do best on nissan cars? i will get some opinion for this guy regarding the reprogramming.

To avritch, i am really a newbie to this measurement thing but no, it is 133% and i was told by the dealer that it should be under 100% and that's all what i know about this. i took a look at the labor part pricing and guess i missed the ECU part--therefore, well, the update is that they charge 600 (in labor and parts) in total for changing AFM (part is 112 bucks) + ECU reprogramming + Changing Air filter (15 bucks). what do you mean by diagnositics? so they should do something after them install the AFM and air filter? i paid them around 100 already for the diagonostics that day and hence my having this 133% data printout. as for the ECU reprogramming, what i heard from the dealer is that if i don't do it, the light will not go off and will come on again and again *_* does this sound a little scary?

actually, i would say that my max shares all of the "mostly" normal issues you mentioned in the end--i have lived with them for years and am still alive it is the service engine light that freaks me out

 

I'm not aware of a MAF made by "other companies."

o2 sensor you can get from wherever....

 

update: i just called the guy this afternoon and he suggested only changing the MAF (around 100) and air filter (around 10), and the labor only cost around 60 yay cannot believe it! he said that the o2 sensor might not be bad yet as the maf can be the ultimate cause to led the o2 sensors to give wrong readings~~

then i asked him if i need to bring the car to dealer for ECU reprogramming and he said no. it seems to him that 2001 maxima does need the ECU thing while my 2000 does not. i have been reading all of the threads in this forum realted to my problem and it seems to me that once the maf got changed the ECU is a must~~ so the question is: must the ECU be done after the MAF has been replaced for this 2000 maxima? well, the dealer told me that it cost "only" 95 bucks to do this--but in case the o2 sensor is bad as well but not changed this time when i did the reprogramming. in the future if i change the o2 sensor too, should i reprogram the ECU again b/c the o2 change?

 

Mine is a 2001 maxima. I replaced the MAF, Reset the Fuel/Air mixture table, and reset the P0171/0174 code. I did not have the ECU reprogrammed. I've gone through 3 tanks of gas, close to 1000 miles on the car since. No further problems were noted. I've also monitored all the OBDII parameters (MAF, LTFT, STFT, Timing, Temps, O2 sensors, etc) and find them to all be behaving normally. Finally, the gas milage has returned to normal. As I said in an earlier post, I'm thinking that the ECU reprogramming simply resets to the Fuel/Air Mixture table back to default levels. If you don't set the table back to default, then you could throw another code (after new MAF installation) since the ECU wouldn't have had a chance to rebuild the table based on the new sensor. I suggest you save the $95 by #1 Install the new sensor, #2 Run the car for 30seconds with the MAF NOT connected (this resets the Fuel/Air mixture table), and finally #3 Reconnect the MAF & clear all the codes. If you have an OBDII scanner, you should monitor Long Term Fuel Trims and see where they stabalize out to over the next few driving cycles (mine settled out to apx -7%... well within normal tolerances).

 

Very interesting! I had the P0138 and P0139 codes first in a 2000 Maxima. The codes point to Bank 2 Sensor 1. This is the Blue harness wire o2 sensor. So i actually cleaned my MAF first, since I read about the MAF potentially being the problem. After that I got a P0154 Code. I removed the terminal from the batter, then reset the codes with an OBDII. Everything is fine for a few days, then the P0174 code comes up-Bank 2 Sensor. What I am going to do next is change the O2 sensor Bank 1 (Blue wire). Next reset the codes, if this does not do it I will replace the MAF.

 

P0171 code It is the MAF, my car is max 2001, replace the MAF (from David B @ $83.00) follow "avritch" method by reset the fuel/air mixture. The car is just like new it passes the Smog and run as I remember the old days when it was new. Thank you all for your help to let me understand to resolve this issue, my thanks goes to arvitech and to David B for his recommendation and good service and support.

 

Hey Everyone....

OK... it's been 4 years an probably about 65K miles... and guess what... the car is starting to hestitate again when initially starting to drive on cold days. Hesitation goes away pretty quickly when car warms up.

Measured the MAF sensor at idle.. .it was apx 2.9 g/s. If I remember right, when the sensor failed 4 years ago, I was reading low 2's before replacing it and about mid 4's after replacing it. So I think the same thing is happening again. The sensor is reporting less air than is actually going through it which causes the computer to send less fuel to the engine.

I've got a new MAF on order.

 

Why not try the MAF cleaner first? It might work.

 

Tried MAF cleaner... didn't do anything. Also replaced airfilter just for the heck of it... no change. Same flow readings on the computer before and after the cleaning

That's exactly what I saw last time... multiple cleaning of the MAF didn't do anything.

I did ask Dave B. at South Point Nissan what the expected life of a MAF should be... he basically said they fail so often, he stopped keeping track.

Maybe I should feel so bad because a full tank of gas is not approaching the cost of a brand new OEM MAF.... ARRRRRGG!!!!!

 

New MAF is in... reads somewhat higher (mid to high 3's g/m as opposed to high 2's to low 3's g/s) that the one that was in there (but not as different as the change 4 years ago)...

This time, my long term fuel trims were not bad... I'm hoping I changed the sensor before they built up...

We'll see if the hesitation goes away...

Again, Thanks to Dave B. as Southpoint Nissan... $83 for the sensor ... arrived in a few days

 

So, did it fix it? What were your numbers at WOT with the old MAF, over 90 g/s?

Which air filter are you running? I hope not the one which is oiled. That will take the MAF out sooner than later.

- Vikas

 

Seems better now ... no hesitation. I do two readings when measuring the MAF.. one at idle and one at 2500rpm (both when the engine is warm)

Idle - 2.8 g/sec on old and 3.5 g/sec on new
2500 RPM - 8.5 g/s on old and 12g/s on new

So definately higher on new sensor, but not as dramatic as last time (but I caught it earlier this time).

I'm running a stock OEM nissan filter.

 

Thanks avritch. I'm having this issue now and my max is 11 years old with 197k miles! Guess I got lucky with my MAF. I will be following the procedure and posting the results when fixed.

 

I just had this same problem on my wife's 2000 GLE (~120,000 miles). The car ran like crap and was hard starting with no power when running. 2 different repair shops I use couldn't figure it out and the car was showing P0171 as a code (left side lean). Based on what I read here, I ordered a new MAF off the internet for a total of $105 and it took less than 10 minutes to replace. The car now runs better than it ever ran before.

Many thanks.

 

hey guys having the exact same issue as everyone else in this post, verified the long term fuel trims are +30 and MAF readings on highway are about 10 to 12 g/s allready ordered the maf sensor but just need to know if someone can verify that do i need the ecu updated after the maf sensor change?

 

If it performs well, then no. If not then yes. I didn't need to, nor did many other people.



8 year old thread.

 

Point being?

 

good catch avritch,

this was also a good fix for me, had the same issues and replace the MAF sensor and problem is gone. also the new sensor comes with a note saying to get an ecu upgrade done because you are installing a upgraded sensor, i didn't get it done an so far i am not having any issues.