1990 Legacy MAF - which one is the right one??

[CharlieLS]

I'm back! With more questions!

So, the MAF sensor on my 1990 Legacy wagon (AWD 5MT) is bad, and I hunted all over to find a new one that fits my car.  Finally found one on PartsGeek that said it fit my year, make, model, and was specifically for manual transmissions.  Unfortunately there were no closeup pictures of it, and when it arrived, it doesn't appear to be the right one.  The one that's been in my car forever is a hot film sensor with a 5-pin (female) connector.  The one I just received has something else going on with the sensor and the connector has only 4 pins.  I've got a partial FSM for the 1990, a FSM for the 1992, and hours of internet searching and I can't figure out if this thing will work in my car! 

So I come to the experts!  Anyone know if this is the right sensor, or if it will work even though it doesn't look like the one I'm replacing?  Thanks, as always, for everyone's help!

[lmdew]

Subaru parts.  www.car-part.com may help you find one.

[moosens]

I’m going through parts as the weather warms. For sure I have the MAF from at least the 92-94 and maybe 90-91. I’m not sure there’s even a difference on that item. Probably all the same for all EJ22E 90-96. 
 

As I can I’ll check the boxes I have which happen to be right up front waiting for spring. 
 

If I have the 5-pin I’ll let you know asap. 

[CharlieLS]

8 hours ago, moosens said:

I’m going through parts as the weather warms. For sure I have the MAF from at least the 92-94 and maybe 90-91. I’m not sure there’s even a difference on that item. Probably all the same for all EJ22E 90-96. 
 

As I can I’ll check the boxes I have which happen to be right up front waiting for spring. 
 

If I have the 5-pin I’ll let you know asap. 

Thank you, moosens!  I know there's apparently a difference only as far as manual/automatic goes - so far, not sure there's anything different as to year, at least not between 90 and 93!  But that's what I've been able to figure out so far.

[CharlieLS]

10 hours ago, lmdew said:

Subaru parts.  www.car-part.com may help you find one.

Thanks for that, lmdew! I will give them a look.

[el_freddo]

Got a part number on it to cross reference? 

[CharlieLS]

On 2/21/2025 at 8:26 PM, el_freddo said:

Got a part number on it to cross reference? 

Well the part number is 22680 AA160F, but when I do a search for it on Subaru Parts, it always comes up "this item is not available," and the ones I see on EBay et al. say that it supposedly fits a 1990 Subaru Legacy, but with an *automatic* transmission...which is part of the confusion!  Is it possible I had the wrong part on there all along, or wouldn't it just not have worked?  I thought I finally had it solved with the one I got from PartsGeek, but it looks totally different (on the sensor part) and only has 4 pins...so basically I'm trying to do historical research and figure out what was *supposed* to be on the 1990 MT all along! 😂

[el_freddo]

22680AA160 is the part number. Drop the F. 

I didn’t think there were different AFMs for manual vs auto. 

My EJ22 converted L series runs that part with its EJ22E. It his is a Gen1 engine and management system. 
The other number on the AFM below the part number is 2X21D on a green and silver label - it’s a five pin plug with all pins present in a plastic housing. My ECU has a “G” on it from memory. 

I hope this helps! 

Cheers 

Bennie

[wtdash]

'90 and '91 5-speeds used the metal MAF - like the '91-'94 EJ22T(urbos).

'90-'94 Automatics and all '95-'98 (and '99 EJ25D) EJ Subarus used the same green label plastic JECS/AUTECS MAFs - only dif is whether they're Japan or USA-made. So,  yeah - limited availability on your year. 

I'd check w/the used auto parts yards for one, too. And try Car-part.com.

Lastly and this may not be a viable option, but do some research on swapping the ECU/ECM to a '92-'94 Legacy as the 5speed and Automatics used the same MAF. Per this pinout diagram the only diff is the 'barometric pressure sensor': https://www.surrealmirage.com/vrg3/ecupins/      But, IIRC, the IAC and injectors were also different on the '90-'91 model. But may still work w/the newer ECU? Just a (bad?) thought. 

For more old Legacy info check here: https://bbs.legacycentral.org/

Edited February 27 by wtdash

[CharlieLS]

On 2/27/2025 at 11:45 AM, wtdash said:

'90 and '91 5-speeds used the metal MAF - like the '91-'94 EJ22T(urbos).

'90-'94 Automatics and all '95-'98 (and '99 EJ25D) EJ Subarus used the same green label plastic JECS/AUTECS MAFs - only dif is whether they're Japan or USA-made. So,  yeah - limited availability on your year. 

I'd check w/the used auto parts yards for one, too. And try Car-part.com.

Lastly and this may not be a viable option, but do some research on swapping the ECU/ECM to a '92-'94 Legacy as the 5speed and Automatics used the same MAF. Per this pinout diagram the only diff is the 'barometric pressure sensor': https://www.surrealmirage.com/vrg3/ecupins/      But, IIRC, the IAC and injectors were also different on the '90-'91 model. But may still work w/the newer ECU? Just a (bad?) thought. 

For more old Legacy info check here: https://bbs.legacycentral.org/

Oof, thanks for the info!  I've had the ECU swapped long ago, but my records don't show what it was swapped for....whether it was another ECU from a 90 or if it was from a compatible year!  Is there a part number I should look for to tell me *that* info?  Hate to contort  myself and get up in there for nothing LOL! 

Looking at the pinout diagram, I see five pins for the MAF but one of them reading only "MAF pin 5"?  What is this mysterious pin 5 - is there a chance that 4 pins would work as well as long as they match up to MAF power supply, the two MAF signal sensors, and the MAF shield?  I did wonder whether it was a turbo thing, as you say that the 91-94 turbos used the same MAF.  Maybe that pin is just not in use in my model year?  Still going to keep searching for the One True MAF but in the meantime, after a cleaning, it's not doing the chug-and-die, sluggish acceleration thing anymore...though something's still just a little *off* and it does some RPM hunting when it's first turned on.  But I drove it up to the mountains and back last weekend and everything was....OK?  (Except the new whirring noise from the left rear wheel but that is...now on the list.  Hoping it's not ANOTHER wheel bearing.) 

Anyway, thanks again for the info and everyone's prodigious knowledge!  Coming here has helped me keep this baby running for 20 years (and counting)!

[CharlieLS]

On 2/24/2025 at 11:50 PM, el_freddo said:

22680AA160 is the part number. Drop the F. 

I didn’t think there were different AFMs for manual vs auto. 

My EJ22 converted L series runs that part with its EJ22E. It his is a Gen1 engine and management system. 
The other number on the AFM below the part number is 2X21D on a green and silver label - it’s a five pin plug with all pins present in a plastic housing. My ECU has a “G” on it from memory. 

I hope this helps! 

Cheers 

Bennie

Thanks for the info!  The only source I'm seeing for a difference between manual and auto is when I try looking up the part number, and how it's listed on various sites selling them.  So yeah, I guess I don't *actually* know if there's a difference that matters.  Looking at the ECU pinout diagram that wtdash linked below, there are 4 pins labelled for signal wires, shield, and power supply, and something just called "pin 5," so that might suggest that one pin is reserved for some other application, maybe something with turbo? (don't know enough about turbos to know).  I'll try looking further using just that part number...thanks again!