CEL Code P0101 MAF Sensor

[FLnative]

The other week my CEL came on with code P0101 Mass Air Flow Sensor A Circuit Range/Performance. I haven't noticed any kind of rough idle or stuttering but the RPMs do bounce around a bit especially while braking.

I cleaned the MAF sensor with the specific MAF sensor cleaner and cleared the code with my scanner, but the CEL came back on shortly after with the same code.

Just wanted to see if anyone had any other thoughts to remedy this before I buy a new MAF sensor. If I buy a new one, any experiences with aftermarket vs OEM?

Pics so this thread is less boring:

 

[Prestige458]

sent you a message

 

[FLnative]

Help Please!

Ok, so I bought an "OEM" Denso MAF sensor off of eBay for super cheap. It looked legit, had all the correct markings on the sensor, and even the box looked spot on. After installing it, the 4runner started up and idled alright, but once I gave the engine any gas it would start to cut out and almost die. I couldn't even make it down my street. I put the old MAF sensor back in and it started up and drove fine.

I drove with the old sensor for a another month or so and the CEL would come on for a week and then go off for a week. I kept hoping it would just stay off but no luck. I didn't see any issue with engine performance and fuel consumption was only a little higher than normal.

Got tired of the CEL so I tried again with just a Denso MAF sensor (non OEM). The engine would start, run for 2 seconds, and then shut off. I tried several times to get it to run, applied the gas while starting, and it made no difference. Engine would run for a couple seconds and shut off. This sensor threw P0102 while I had it in. I put the old sensor back in and it fired right up again but had the CEL still.

Is there something I need to do to sync up the a new MAF sensor to the 4.0 V6? Any ideas what's going on? My mpg dropped close to 4mpg, down to 14mpg, on my last tank so I'm not sure exactly what's going on with that either now.

Need some help before I hang my head and take it into a shop.

 

[81runner]

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If your scanner has live data, look at your long term fuel trims (ltft1, ltft2) do they match? Are they high, like 20-30%? I got this code in conjunction with P0171,P0174 leaning bank 1 and lean bank 2. Replacing the MAF corrected the issue for a few miles, but the lean bank codes came back. Now, my MAF that drew the code is a high performance MAF, so I'm guessing it went out of whack because increased fuel trims. I narrowed problems down to the fuel pump, which I am anxiously waiting for. This is just my experience, but I would look at the fuel trims with the new sensor installed versus the old one and see if anything changes, it what they are to begin with. An engine dying is losing spark, losing air, or losing fuel.
Check for vacuum leaks down stream of the MAF as well

 

[TheTurboMRT]

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If your scanner has live data, look at your long term fuel trims (ltft1, ltft2) do they match? Are they high, like 20-30%? I got this code in conjunction with P0171,P0174 leaning bank 1 and lean bank 2. Replacing the MAF corrected the issue for a few miles, but the lean bank codes came back. Now, my MAF that drew the code is a high performance MAF, so I'm guessing it went out of whack because increased fuel trims. I narrowed problems down to the fuel pump, which I am anxiously waiting for. This is just my experience, but I would look at the fuel trims with the new sensor installed versus the old one and see if anything changes, it what they are to begin with. An engine dying is losing spark, losing air, or losing fuel.
Check for vacuum leaks down stream of the MAF as well

Did you get your issue resolved? I have 20-30% LTFT, occasional P0174. I've tried a new MAF from Rockauto (Toshiba, same as OEM) and no change. LTFT on throttle is fine, but at cruise and idle is 20-30%

 

[81runner]

Did you get your issue resolved? I have 20-30% LTFT, occasional P0174. I've tried a new MAF from Rockauto (Toshiba, same as OEM) and no change. LTFT on throttle is fine, but at cruise and idle is 20-30%

I did replace my fuel pump. Trims became more tolerable, but still kind of high, in the 20s. Wound up changing the injectors and pressure regulator. Trucks runs like new now, and the high performance MAF I was getting the code with is also back in, all working well.

 

[waypoint]

I did replace my fuel pump. Trims became more tolerable, but still kind of high, in the 20s. Wound up changing the injectors and pressure regulator. Trucks runs like new now, and the high performance MAF I was getting the code with is also back in, all working well.

This is a great data point. Maybe the fuel pressure regulator had a failed diaphragm or weakened spring? Or maybe one or more injectors was underflowing?

 

[81runner]

This is a great data point. Maybe the fuel pressure regulator had a failed diaphragm or weakened spring? Or maybe one or more injectors was underflowing?

I feel like, in my case, it was injectors clogging and fouling intermittently with a regulator failing. Cold engine trims were elevated but tolerable, but would get progressively worse as the engine ran. Since the numbers remained consistent and didn't fluctuate wildly, I ruled out any sensors malfunctioning. Also, sensor voltages looked ok after I was all done. It's worth noting, after every repair or group of repairs for this problem, it's a good idea to pull the positive lead from the battery and force a reset.

 

[TheTurboMRT]

Thanks, I will try a FPR first, follow up with injectors. These are my exact symptoms, from cold start to warm idle

 

[81runner]

Thanks, I will try a FPR first, follow up with injectors. These are my exact symptoms, from cold start to warm idle

My advice would be to just do it all. Reason being: the fuel pressure regulator and the injectors are all on the fuel rail. No sense in taking it off twice, if you remove it then put back all new parts. Your truck will thank you

 

[TheTurboMRT]

My advice would be to just do it all. Reason being: the fuel pressure regulator and the injectors are all on the fuel rail. No sense in taking it off twice, if you remove it then put back all new parts. Your truck will thank you

Where'd you get your injectors?

 

[81runner]

I found my injectors on Rock Auto. I went with denso. I've also seen remanufactured injectors all over eBay and Amazon for cheaper, if you trust such things. I would say if you are going reman, go with the guy that has the best reviews. And stick with denso, no off brand junk. And make sure they come with seals as well.