MAF sensor weirdness

Hi all - I've been having this weird thing happen with my '01 v6 ext cab, manual trans. Every three weeks or so I notice the engine is running rough (sputtering a little at idle and tentative acceleration). I've assume it's the MAF sensor so I clean it, disconnect and reconnect the battery afterwards so the computer resets, and it's fine for a while. Then about 3 weeks later, rinse and repeat. Any ideas? I'm hesitant to replace the sensor if that won't solve the problem. Thanks for your help!

 

Check Engine Light coming on when it acts up? Have you checked for any codes?
What are you cleaning it with?

 

The code is p0171 and I’ve been cleaning it with CRC MAF Cleaner.

 

Have you checked your A/F sensor?

 

Thanks, I’ll check that. The weird aspect of this is that the issue corrects itself when I clean the MAF. It leaves me thinking it’s something related to that. What’s does the A/F do?

 

You also said that you're reseting the ECU each time you clean the MAF- so it's more likely that what you're labeling as "corrects itself" is actually the time it takes for the ECU to run all its monitors and determine something is out of spec.

 

That’s possible, but I typically drive the truck for 3 weeks and 100+ miles with no issue after cleaning. Does the ECM typically take this long to complete a monitoring cycle?

 

Yes, it can take as little as a few miles or as many as a thousand or more. There are certain parameters that have to be met while driving for all the monitors to complete their cycles

 

https://parts.olathetoyota.com/air-fuel-ratio-sensors

 

You shouldn't have to clean the MAF more than once. Either the MAF is higher than a kite on the cleaner (lol) or something else is causing your system to throw the P0171. Perhaps its simply your MAF and needs to be replaced. I'd be checking everything else first before throwing parts at it.

It measures the oxygen content in the exhaust and provides feedback to the computer. Based on that, the computer adjusts the air to fuel ratio to keep it at the optimum level.

Since you're seeing a P0171, start with these areas (why I included the A/F sensor info in post#4 - easiest to check next) -

 

The drive cycle for P0171 is -

(a) Connect the OBD II scan tool to check monitor status and preconditions.
(b) Start the engine and allow to idle for 2 minutes or more.
(c) Drive vehicle at 40 – 70 mph or more for at least 150 seconds.
(d) Stop vehicle and allow engine to idle for 10 seconds or more.
(e) Drive vehicle at 25 mph or more for at least 40 seconds.
(f) Stop vehicle and allow engine to idle for 10 seconds or more.
(g) Perform steps ”e” and ”f” 10 times.
(h) If readiness status does not switch to complete, ensure preconditions are met, turn ignition off and then repeat steps ”a” through ”g”.

 

Maybe get a used MAF from a salvage yard. Rule it out if it does the same thing. Check all vacuum lines, ground wires etc. What condition is the throttle body in? How about the Idle Air Control Valve?

 

Thank you so much, this is super helpful! I had no idea that the ECM had such an involved cycle - it makes sense that it’s taking 3 or so weeks to readjust because my wife has been driving it and she doesn’t put many miles on. I'll pull the O2 sensor and check for resistance like you recommended. I don't have a lift - is it easy to pull by just laying under the truck?

Also - would it make sense to do a resistance test on the MAF?

 

Even without an aftermarket lift, you should be able to get to the sensor. If not, toss it on a jackstand.

If you do want to check the MAF -