is my MAF almost dead?

[bowlofturtle]

2009 Forester with 70k miles on it. Had a CEL for P0102 and P0113, ones for IAT high input and other is MAF low input.

Checked around, intake pipe is GOOD. MAF sensor plugged in. Nothing loose or out of place. I clear the fault and the car seems to be running ok. Took it around the block and all is well. Good power no idle issues.

Later on i started it up again, it hesitated. Like upon start up, the first 2 seconds it was stumbling and then idled. I thought maybe thats the boxer way since its not my car. No faults or anything. I go unplug the MAF, it hesitated again and went back to normal. Gave me the same 2 faults. I went to plug the MAF back in and car died instantly. Started it up and it worked. Minor surge every now and then.

Does this seem like a dead MAF sensor to you? I'm just going off when i unpluged the sensor i got the same 2 faults that showed up. So maybe its on it way out. But its about $200 so i dont want to random guess it.

 

[Trav]

Sure sounds like a bad MAF, the symptoms are all there.

 

[KB2008X]

This seems like the kind of issue that you may get a more detailed answer to, on a Subaru forum. You really need the Subaru MAF test procedures for that engine if you want to be more certain that it is failing, but I do agree that it would appear to be the prime suspect.

Keith

 

[Mud]

Did you try cleaning it? Use electrical contact cleaner/spray, don't touch the wires. I do this on our vehicles as regular maintenance along with cleaning the throttle body.

 

[LeakySeals]

Yeah an actual electrical code would indicate a hard failure over dirt/laziness. If you cleaned it, with what?

 

[The_Jeff]

I'd try and watch the live data. My volvo had a vacuum leak by the cruise control and there was very little air travelling over the MAF so it would inject very little fuel. Its programming was dumb enough that it doesn't assume a minimum idle airflow.

When you unplug the MAF you usually get a high, rich idle as a fail safe that covers a number of faults, not just a MAF one.

 

[Trav]

If you end up needing a new one do not buy a reman!
They are iffy at best, i haven't had a good one yet and gave up on them.
Look for a new Denso or Hitachi unit or a used one.

 

[bowlofturtle]

Originally Posted By: KB2008X
This seems like the kind of issue that you may get a more detailed answer to, on a Subaru forum. You really need the Subaru MAF test procedures for that engine if you want to be more certain that it is failing, but I do agree that it would appear to be the prime suspect.

Keith


I did post on 2 bigger subaru boards. Not much help. Cant find a online FSM anywhere.


Originally Posted By: Mud
Did you try cleaning it? Use electrical contact cleaner/spray, don't touch the wires. I do this on our vehicles as regular maintenance along with cleaning the throttle body.


Never cleaned it. I'm not sure what i make of that CFC MAF cleaner.


Originally Posted By: Trav
If you end up needing a new one do not buy a reman!
They are iffy at best, i haven't had a good one yet and gave up on them.
Look for a new Denso or Hitachi unit or a used one.


not much choices. ebay has random ones for $50-75. Rockauto has either SMP or cardone remans. Didn't quote out a dealership yet.


Overall to me it sounds like its the MAF. But not having much experience with subies and their boxer motors, i dont know what is normal and what is not. Might have to go ebay route on this one.

 

[Volvohead]

Originally Posted By: Mud
Did you try cleaning it? Use electrical contact cleaner/spray, don't touch the wires. I do this on our vehicles as regular maintenance along with cleaning the throttle body.


Yes. Cleaning a dirty MAF can save a lot of "bad" ones. For the particularly lazy:

http://www.amazon.com/CRC-05110-Mass-Sensor-Cleaner/dp/B000J19XSA

Otherwise, visit any corner auto supply store.

If cleaning won't recover it, on some vehicles. try to replace just the element (and not the entire MAF assembly). The difference can be in the hundreds. Unless strapped for cash, OEM quality gives the least headaches.

 

[Volvohead]

Originally Posted By: bowlofturtle
2009 Forester with 70k miles on it. Had a CEL for P0102 and P0113, ones for IAT high input and other is MAF low input.


P0102 is sometimes just a dirty MAF. I'd clean it first as previously noted. FWIW, the business end of a MAF is just a small encapsulated bulb on most newer vehicles. Easily cleaned. The element and assembly around it makes folks think it is some untouchable NASA-like test instrument. It's not.

You're right about P0102. That is the IAT. First check the connections and the harness condition.

The IAT is thermistor driven. Again, like the MAF, it can throw a code if it gets too dirty.

Did someone play with the intake tract on this? Careless work or half-hiney cleaning methods can cause this result.

 

[Mud]

I've used the CFC brand cleaners (electronic contact, TB, etc) with great results, they are fine.

I also have a set of HF security bit fasteners that make removal of "non-tamper" screws a breeze.