My daughter's 1996 Legacy with 116,000 miles on it is giving symptoms reminding me of our Forestor when the MAF was bad about 14 years ago. At that time I just dropped it off at the mechanic and they replaced the MAF.

I have a Code reader that provides freeze frame data and live data. Any suggestions on what I should look for in this data to determine if it is the MAF?

I'm thinking of getting some MAF sensor cleaner, but from the severity of the symptoms probably the MAF is already dead. 

Anecdotal, but I had a 1996 legacy a few years ago with a bad MAF and no codes.  Swap MAF, all good.

You probably know this but knock sensors are routinely problematic on those as well.  I've installed a ton of $6 ebay specials with no issues. 
Pull the sensor and the bottom is usually corroded/cracked. Usually you get a code obviously. 

I assume there's no check engine light or pending codes if read?

 

Just now, idosubaru said:

Anecdotal, but I had a 1996 legacy a few years ago with a bad MAF and no codes.  Swap MAF, all good.

You probably know this but knock sensors are routinely problematic on those as well.  I've installed a ton of $6 ebay specials with no issues. 
Pull the sensor and the bottom is usually corroded/cracked. Usually you get a code obviously. 

I assume there's no check engine light or pending codes if read?

 

She is bringing the car over this afternoon and I'll plug in the code reader.

A bad MAF doesn't always set a code at least on the 90's subaru.  Cleaning it is not the answer.  Just go to a junk yard and get another one.

'92-'98 ('99 SUS/GT/OB) 2..2 (NA) and 2.5 are all compatible....Green Label versions...AUTECS (USA) and JECS (japan).

24 minutes ago, wtdash said:

'92-'98 ('99 SUS/GT/OB) 2..2 (NA) and 2.5 are all compatible....Green Label versions...AUTECS (USA) and JECS (japan).

So are you saying the MAF for a 98 Forester with the EJ25 engine is the same as in the EJ22? If so, I can swap out the MAF from our 98 Forester and see what happens.

100%>>.. '98 is only year.  ...'99+ No.

Edited November 29, 20187 yr by wtdash

Yeah all those old 90's ones are the same. Even the early 90/91 stuff can be swapped to the newer style. Including turbo models IIRC.

GD

Edited November 29, 20187 yr by GeneralDisorder

4 hours ago, GeneralDisorder said:

Yeah all those old 90's ones are the same. Even the early 90/91 stuff can be swapped to the newer style. Including turbo models IIRC.

GD

Yep on Automatics; 5-speeds had the metal one like on the '91-'94 turbo - thought those were incompatico.

Edited November 30, 20187 yr by wtdash

I've seen the metal one's swapped over to the plastic one's with seemingly no issue. Seen it done a couple times now. 

GD

Not that hard to fix; got staggering estimate from local shop on my sister's car for that and other issues, that were tune up related.  I got a good used unit, end of story, no problems followed.

Here is an update on the car. Since last Thursday there have been only intermittent problems with the car. I did spray MAF cleaner on the sensor but it already looked clean. Also since then the CEL has been off, but it was never on for the MAF sensor.  It did come on from time to time for the Idle Air Control Valve. We bought a used Idle Air Control on eBay for $80 and I just installed it now. I took the car for a test drive and did not notice any problems.

The old Idle Air Control Valve was part 22650 AA033 and the Subaru dealer told the updated part number is 22650 AA034 so I got that one.

It looks like top part can be turned to make adjustments. Does anyone know anything about that? There are two little screws one can loosen like on the Throttle Position Sensor. I’ve attached a picture.

Only adjustment procedure in the FSM uses the Subaru Select Monitor. This is from the 99 Legacy Manual so hopefully it's the same.

You can get an FSM for your year/model here https://sl-i.net/FORUM/showthread.php?18087-Subaru-Factory-Service-Manuals-

MSA5TCD99L97.pdf

What symptoms were you trying to solve? You never mentioned.....

30 minutes ago, GeneralDisorder said:

What symptoms were you trying to solve? You never mentioned.....

Hesitation and jerking during acceleration, engine stalling.

 

 

Remove and clean the throttle body. Idle issues are more often a result of the idle control being driven to its limits by a throttle body that is inconsistent, dirty, and isn't contributing consistent airflow at idle. Causing the computer to send max idle pulse widths, etc and it is unable to compensate for changing idle loads when it's already at it's limit. 

GD

9 hours ago, GeneralDisorder said:

Remove and clean the throttle body. Idle issues are more often a result of the idle control being driven to its limits by a throttle body that is inconsistent, dirty, and isn't contributing consistent airflow at idle. Causing the computer to send max idle pulse widths, etc and it is unable to compensate for changing idle loads when it's already at it's limit. 

GD

I did clean the Throttle body a few months ago, but did not remove it.

You didn't mention that you had gotten the idle control valve sensor code!  Of course when you get that code, it's a no brainer to replace it.  I had that failure on a 97 where it would hesitate and nearly stall in traffic. Yes, the adjustment is critical.  It doesn't require the use of the "subaru select monitor" but it did require sticking pins through the wires of the sensor so that the voltage could be measured.  Use the search engine to find the procedure.

And cleaning the throttle body in place isn't totally effective as SSI implied.  Maybe it would work and maybe not. You can't be sure. But if you got the code, then fix the ICV sensor.

 

20 minutes ago, mikec03 said:

You didn't mention that you had gotten the idle control valve sensor code!  Of course when you get that code, it's a no brainer to replace it.  I had that failure on a 97 where it would hesitate and nearly stall in traffic. Yes, the adjustment is critical.  It doesn't require the use of the "subaru select monitor" but it did require sticking pins through the wires of the sensor so that the voltage could be measured.  Use the search engine to find the procedure.

And cleaning the throttle body in place isn't totally effective as SSI implied.  Maybe it would work and maybe not. You can't be sure. But if you got the code, then fix the ICV sensor.

 

Thanks! I’ll see about finding the instructions on adjusting the Idle Air Control Valve. My daughter reported last night the car hasn’t misbehaved since I replaced the Idle Air Control Valve. The car runs normally. What happens by not checking to see if the voltage is correct? Maybe just not get optimum performance from the engine?

The misbehavior returned. I got a used MAF for $50 and no more misbehavior.