MAF sensor - now one is causing stalling ?

[hernonm]

Hi,

I bought an MAF sensor on ebay (just the sensor...which can be removed and replaced w/ two start screws). I put the 'new' sensor in and started the car and it started driving like s***. Stalling, sluggish, etc. I drove it for a bit but quickly put back the old sensor and the car started driving fine.

SO my QUESTION is, do I need to bring it into the dealer after replacing the sensor and having them recalibrate the ECU do to the new sensor? I read that this would need to be done and read that it would NOT need to be done in different forum's. Also, when I called Nissan about replacing the MAF myself they said, yes we sell it but realize you 'may' need to have the ECU changed.

Thanks in advance...

-M

[maxhopper]

If it's running that poorly, I would think you got a bad sensor.

[hernonm]

Thanks for replying.

The car has been running find outside it is a big slugggish 'first' thing in the morning (goes away in 200/300 feet of driving). Th engineer light is on and i am getting the two codes that indicate lean 1 and lean 2 banks. I did some research online for the sluggishness (upon first start and accelerate only in the morning) and the bank lean codes and a few people recommended replace the MAF sensor. Now you can get the whole MAF unit including the sensor or you can just by the sensor and remove it w/ one of those star screwdrivers which I did. Replaced the original one w/ the new one I bought on ebay and that 'is when' it started rough, hesitated, etc. I replaced it with the original and now it's back to the previous behavior.


SO back to my QUESTION. Do I eed to bring it into the dealer after replacing the sensor and having them recalibrate the ECU do to the new sensor? I read that this would need to be done and read that it would NOT need to be done in different forum's. Also, when I called Nissan about replacing the MAF myself they said, yes we sell it but realize you 'may' need to have the ECU changed.

The reason I am doing this is to get the engine light fixed .....

[loystock]

I agree with 'maxhopper' that you probably bought a crappy sensor from eBay. Another possibility is that you touched the sensing element with bare hands and contaminated it (oil, sodium, etc from your hands).

Disconnect the MAF sensor and start the car. It should start smoothly since the ECU will use the default fuel/ignition map but CEL will be ON for obvious reason. Do not drive the car as it will be in 'limp mode' (limited to @ 2800 RPM) w/o the MAF sensor. If the car starts smoothly w/o MAF yet runs very rough with the new sensor, then your sensor from eBay is bad.

The ECU should be able to learn parameters from new sensors, like MAF, over time. Driving on city streets and doing multiple stop-and-go as well as some WOTs on a highway (no need to over-speed nor be reckless) can accelerate the learning process.

You can clean the old MAF sensor with CRC MAF Sensor Cleaner or any zero-residue Contact Cleaner. You might as well check the entire intake - replace the air filter if dirty, clean the TB (do not spray cleaner directly into it, use rag), check for a intake, vacuum and for exhaust leaks. An exhaust leak can result in a lean sensing from the O2 sensors.

[hernonm]

Sorry 'maxhopper' i 'misread' your post. I thought you meant running 'poorly' before trying the new sensor. That is why I explained the situation again. I did ping the seller from ebay and am awaiting feedback from them.

Before trying the new sensor I did everything you mentioned 'loystock' (bought MAF cleaner and cleaned it as well as the TB) and initially the engine light went out (i was thrilled) however it eventually (after about 40 miles) went back on.

The fact the engine light went off be a true indicator that the MAF is bad? Note, the car is initially sluggish (i have to slightly pump the throttle) and then it's fine the rest of the day. Would this be indicative of a bad MAF.

Regarding the 'new' sensor, I was very very careful to not touch the sensor so most likely it is probably a bad one. I still wonder why the Nissan Dealer would tell me a I 'may' need to bring the car in to have the ECU reprogrammed if i replace it myself. Note, an online OEM Nissan parts dealer told me the same. Actually, I think that guy told me it was dependent upon 'when' the replacement MAF was created.

I will try out what you recommended regarding 'disconnecting' the 'new' (after I put it in) and starting it....

Thanks guys, I appreciate it!

[loystock]

If time and money is not an issue. ECU re-programming at the dealership is good as they may have the latest SW upgrade. The cost is @ $100. When the Throttle Body in my 03Q was replaced under warranty, Beshoff Infiniti did not charge a single cent for diagnostic (@ 4 hours), component replacement and ECU SW upgrade. I love Beshoff!!!

[hernonm]

I would be fine spending the $100 if that was the reason the new sensor was making the car stall. If that resolved the engine light then it would be $160 total ($60 for the sensor and $100 for labor) however I am not sure if that is the case or it's a bad sensor. Of course Nissan isn't going to want me to drive and and say I have just installed a replacement sensor from Ebay and now the car is running like crap (they may even tell me the won't help me unless i install nissan parts). The cost for the 'whole' MAF assembly (this includes the sensor) is $140 at this dealership and $90 shipped from the Scottsdale Infinity dealership. So, once again I am not sure if the sensor I bought on Ebay is just 'fine' it's simply a fact once replaced the car needs to be reprogrammed.....

Thanks again...

[loystock]

If you have confirmed that the new MAF sensor is causing your car to stall, then it's bad. We have several members here who have successfully replaced MAF sensor w/o any reprogramming from the dealership. I never have had any problem with the MAF sensors (knock on wood) in my cars as I clean them every 2 years, use dielectric grease on the connector and replace air filter every year.

[hernonm]

Thanks loystock. I am going to return the sensor to the ebay seller, he sent me an RMA #....I was just ruling out that possibly the sensor was fine however the issue was the need to have it reprogrammed. I will return it and buy another one and see what happens......

[hernonm]

One more general question. I am finding more and more that my car is initially very sluggish in the morning as I leave the driveway. It goes away w/i 100 feet however when i give it the gas it's just slow to respond (ie. sluggish) almost like i have to pump the peddle a bit and then wham......the problem goes away. I've seen other message boards make reference to the fact that this type of sluggishness is related to a faulty MAF sensor and my engine light is on as well....p0171 and po171 (lean bank 1 and 2 code)...i was HOPING by replacing the MAF sensor and clearing the engine light this issue as ewell as the engine light would go away so i could get my sticker !

[loystock]

So let's clarify your case. You replaced the MAF senso9r because you have lean codes for Bank 1 and 2. So I'm assuming that you have P0171 and P0174 and not just P0171. Well, replacing the MAF sensor may or may not fix the problem. After cleaning the MAF sensor, did the car run smoothly or sluggish as before? If it ran smoothly, then you have an erratic MAF sensor. BTW, which model year do you have?

A lean mix problem may be due to air intake/exhaust leak, front O2 sensor, fuel injector(s), or problem with fuel delivery.

If the MAF sensor is good and since you have lean codes in both banks, your problem may be on fuel delivery - weak fuel pump, dirty/clogged filter or malfunctioning Fuel Pressure Regulator (assuming you have checked the intake and exhaust for leaks). When was the last time you replaced the fuel filter (on firewall near brake booster)? You may have to check fuel delivery by connecting a Fuel Pressure Gauge between the Fuel Filter and Fuel Rail - 43 PSI with Ignition ON but engine off and 34 PSI with engine running. You also have to do a leak down test. After shutting down the engine, the fuel pressure should remain steady and drop gradually (a sharp drop indicates as problem somewhere - fuel pump check valve, fuel pressure regulator or injectors).

You have to make sure the fuel line is empty before breaking it - FIRE HAZARD. With engine running, pull out the Fuel Pump fuse (driver side fuse panel) until the engine dies and crank a couple of times. If the fuel filter is good, you should be able to blow thru it with very little resistance.

[hernonm]

Initially after buying the car (I stupidly bought it w/ an engine light issue) as it was running fine and still is outside the 'first thing in the morning sluggishness'. Like I said, that goes away pretty much immediately (within driving 10-20 feet). I did take out the MAF and clean it once. To be honest I was paying attention to the early morning sluggishness like I should have been, I was focused more on the fact the engine light went out and stayed out for about 50 miles, then came back on (note, I didn't reset and clear the ECU). I was figuring the cleaning of the MAF was the engine light issue until it came back on. :-( Note, I also clean out the TB as I remember in my old maxima that could get sticky.

I read online about a few issues with Maxima's (my car is a 2000 I30t) and sluggishness and MAF sensors so I figured why not replace it and see what happens. I went the cheap route and just replaced the MAF sensor and not the whole unit. I have since returned it, telling he ebay vendor it made my car run like crap which it did, so maybe it was faulty.

Well not sure I am up for checking the fuel issue, so I may most likely need to go the deal route which i really do NOT want to do as they could start jerking me around, throwing parts at the problem, telling me they need to 'reprogram' the ECU (they told me it costs $100 to do that if they have to replace the MAF), etc. I probably could replace the fuel filter myself I did that on my Maxima. Do the parts stores sell the fuel pressure gauges?

How do you check for exhaust leaks? I do hear a little rumbling when I start the car up but not sure how to really check for leaks that could be part of this issue. Is it simply by feeling my hand along the exhaust seeing if i feel pressure coming out (ie a leak)?

Thanks for your help again...