1990 Legacy codes 24 and 35 Engine dying

[cemmes]

My 1990 Subaru Legacy has 198k mileage. 
 

for the longest time I have had issues with it stalling at low idle, mostly when letting the gas off in parking lots. I recently decided to try and address this, per the recommendation from a local mechanic, and switched out the MAF. 
 

after approx two weeks From changing out the MAF I started having issues with the car stalling while driving. Driving home one day, car started revving funny at a light then died. Restarted, drove a little, then died. Almost acting like it was out of gas. Which is what I honestly thought was the issue. I Drove as far as I could before it stalled and wouldn’t restart. After approx ten minutes, tried to restart, turned right on and I drove to nearest gas station to fill up. Continued on fine and made it home. No issues for the next day and half or so.
 

flash forward a couple days. Turned my car on after work to warm up. After it warmed up it stalled. Tried to restart and wouldn’t. Let it sit ten minutes and it started right up. Drove as far as I could and it did the same thing. Stalled, let it cool some, restarted. Eventually it stalled and wouldn’t start. Next day came back to get car, started right up and drove it home.

 

tried switching back to my old MAF and problem still persisted. Tried to disconnect battery to reset ECU and it wouldn’t even start now. 
 

pulled the codes and come up with: 

24, air control valve inoperative (Abnormal signal produced in monitor circuit
35 Canister purge solenoid valve iniperative

Now I’m wondering if either of these could realistically be at fault? I checked fuel at the filter, seems to be pumping. Based on the way it’s acting, it seems like a fuel issue either from pump or mixture at MAF, 
 

I have a k and n filter that probably needs to be cleaned. Could that be contributing to an issue? Or oil on the MAF sensor?
 

hmmmmmmmmm....

Edited December 13, 2019 by cemmes
Typos/clarify

[Rampage]

13 minutes ago, cemmes said:

after approx two weeks From changing out the MAF I started having issues with the car stalling while driving

Had the same kind of problem with one of our Legacys about 5-6 months ago. I was charging the A/C system and the engine stalled. Restarted and it stalled in 3-5 seconds. I ordered an off brand MAF Sensor online and it worked good for about 4 weeks then the engine started loosing power. I went to a local yard and grabbed two of them. Cleaned one of them with MAF Sensor Cleaner, put it on and the engine ran good like it used to.

Any kind of dust or dirt or even a tiny bug on the filament can mess up the signals from the MAF Sensor. You could try the cleaner, but it will only fix it if dirt is the problem.

One thing about "some" OBD1 systems, If you disconnect the battery to clear codes, when you start the engine the Engine Control Module will be expecting to see perfect signals from all new sensors. So, if the MAF Sensor is not up to par it could set the code almost right away. It did on my 93 Ranger 4.0. I cleaned the MAF Sensor and it was fine.

Code 24 - Idle Air Control Valves seldom go bad. You could look at the contacts on the plug for corrosion. You could also try a cleaner on it.

[cemmes]

So I took my IAC valve off and cleaned it well with carb/choke cleaner and checked the resistance between contacts as my Hayn manual suggested. Was wondering if there is someway of putting 12v to it and seeing it move?

 

cleaned my MAF too and checked all the vacuum hoses I could as best I could. 
 

took the air filter out to clean it, didn’t put it back in yet.  But tried to start it and it just cranked over, no start. This is with my original MAF that was working fine except for the random stall and easy restart like in a parking lot.

 

 

[cemmes]

I still had my diagnostic plugs together under the dash. Would this prevent it from starting or can it run with these together?

[Rampage]

4 hours ago, cemmes said:

I still had my diagnostic plugs together under the dash. Would this prevent it from starting or can it run with these together?

I don't think it will start because the ECM is in test mode, and I don't know if trying to start it would hurt the ECM or not.

Maybe someone else knows.

I would not put 12v on the IAC valve without looking at the factory service manual.

Unplug the MAF sensor and see if it tries to start.

I found another post where the MAF sensor caused the rough idle and stalling and that caused the code 24 to be set.

[GeneralDisorder]

Neither the IAC, nor the test connectors will cause a no-start. 

Unfortunately, without live data from the ECU, you have no real way to determine if the sensor inputs make sense. I reccomend you order an OBD-I SSM cable and download EVOScan to see what the ECU is seeing.

GD