Mass Air Flow Sensor Issue.

Discussion in 'Newbie Section' started by Almera2001, Aug 16, 2016.

  1. Almera2001

    Almera2001

    Messages:
    6
    Likes Received:
    0
    Model:
    N16 1.5 90hp MKII Hatchback
    Chassis:
    n16
    Not sure where to post this so I hope I'm not breaking any rules.

    Just want to let you know about a recent issue I was having on my N16 1.5 2001 Hatchback.
    I had bought the car a month ago and the previous owner had said it hesitates a small bit while accelerating through the gears. I thought it would be just the plugs or something. But over the course of a couple of weeks it got worse and worse.

    She wouldn't rev past 4k at all, even while in neutral. I thought straight away the cat converter had shat itself. So I hooked up my obd2 scanner and here's the following readings I received.

    First off the check engine light was on and was showing a p0171 code (System too lean bank 1). So then I went and got up my short term and long term fuel trims, MAF rate (g/s), throttle position, upstream and downstream o2 sensors. At idle, the STFT was constantly dropping to -25% and then back up to 0% again while the LTFT was sitting at 37% and wouldn't change at all. MAF rate was reading 2.3 g/s which I thought was normal. Both o2 sensors reading a rich mixture. The second I hit the throttle the STFT shoots up to 25% and the LTFT would drop to about 28% and then the o2 sensors would read too lean. But if I hold it at 2.5k revs the o2 sensors read the normal readings (o2 upstream going from .1 to .9v constantly). While driving and I dump the throttle the engine just misfires constantly and will not go past 4k, sometimes only managing 3k revs but I did notice the MAF readings were a little bit low. So I took out the sensor, cleaned it with MAF cleaner, properly, afterwards she still hesitated and had serious lack of power. I checked the wiring harness to the MAF and the signal voltage was about 3.5 volts which is a bit low. So I then checked the fuel lines and injectors, all seemed fine and I had full fuel pressure too. Eventually bit the bullet and bought a new MAF. Installed it this morning and now the car is running absolutely perfect. No more hesitation, no more check engine lights, all the power seems to be there now.

    I bought the MAF off of ebay for €50, an aftermarket one. I know these are frowned upon but fuck it, in my local Nissan dealer they were asking for €450. A bit steep when you don't have the money. I'll see how well or even how long this MAF lasts and how well it works too.

    Just thought I'd share this with you. Any questions feel free to ask.
     
  2. Prim gt

    Prim gt

    Messages:
    844
    Likes Received:
    80
    Location:
    North East
    Model:
    Primera gt/almera ph1 sport
    Chassis:
    P11 + N16
    Yup I've had nearly the same on the n16 sport ie would not rev over 3k and bogging down nearly no power which got slightly beter as the engine warmed up (Never stalled and always started ok) But my Maf readings were ok on live data and I didn't have thev EML on either.So I fitted a cheap maf from ebay more in hope than anything else and all power was restored but I had a major hiccup at around 5k mark plus I got the random stalling at junctions which I didn't have before so i knew right away it was due to the cheap maf also being faulty,so I replaced it with a bosch maf (£85 new) and that hiccup disappeared.
     
  3. Bosse

    Bosse

    Messages:
    1
    Likes Received:
    0
    Location:
    Sweden
    Model:
    Almera
    Chassis:
    N16
    thanks for your post, it seems like P0171 in most cases is MAF problems
     
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