Engine issues are driving me crazy! '96 Impreza 2.2L

[1996BlackBauer]

Alright guys I am pretty much lost with this. My '96 Impreza 2.2L will just randomly run bad with no warnings what so ever. what will happen is that it will randomly have a few misfires, then just start dying, and coming back to life, throttle response does nothing to bring it back most of the time, it just continues to run bad, and after a few seconds of that it will die. When i go to restart it takes forever, and runs like crap. Occasionally it will just be like somebody flipped a switch and it will run good again.  Not sure what is going on here, I have tried to replace some parts that I thought might be the issue due to being soaked with oil due to leaks. 

 

Things I have replaced:

 

-Oil sender/switch(This was the oil leak that made every sensor covered in oil). 

-Knock sensor, had a code for it, and it was cracked.

-Crankshaft position sensor(had codes sometimes, but was filled with oil, so I replaced it, no codes recently.

-Coil pack, replaced it with a Subaru one off of my friend slow mileage Forester

-spark plugs are newer (NGK), maybe 3k on them

-upstream o2 sensor, had multiple codes for it(no codes since replacement, with miles put on it)

 

 

things I have checked and done:

 

-Checked for Vacuum leaks, none found

-Cleaned MAF, it was dirty, but appears to work just fine

-Cleaned throttle body

-replaced crappy Fram air filter for a quality one

- checked resistance for plug wires(they are within spec)

- cleaned out any connectors with oil, grease or dirt in them.

 

 

I also have a video of it happening, not the best quality, but you can see what I mean. 

The check engine light is on only because I unplugged the Camshaft Position sensor while it was running.

I NEVER have any misfire codes ever. 

 

 

 

Here are the reading from the sensor after it got to operating temperature.

 

MAP(inHg) - 8.3

Engine RPM - 700 +/- 30rpms

Spark Advance 14.0

MAF - 0.4-0.5

ECT(in degrees F) - 165-170

STFT - 0.0

LTFT - -2.3

 

These are all the specs I can get out of the scan tool that I have. wish I could see more, but I can't.

 

Any input would be very helpful. not sure where to go next, I am a Mechanic, so I have tools, and mechanical knowledge. 

 

[Fairtax4me]

Probably the MAF sensor going bad. Pretty common issue on the mid 90's cars. 

 

The common problem with those is a the solder joints will crack where the pins from the connector meet the pins that come from the PCB inside the housing. 

If you cut the silicone out from around the square on top, you can pry the top off and you'll see where the pins join. Hit those with a soldering iron and re-solder them. Stick the top back on and run a bead of silicone around it to re-seal it.

Most of the time that seems to fix it. 

 

Just watched the video, symptoms aren't exactly like what I'm used to seeing from a failing MAF, but possible yours is failing. They can cause all sorts of odd symptoms. Have you watched the MAF data while its acting up to see if the MAF flow rate is dropping too low? 

 

Also have you tried to check fuel pressure while its doing this? Could be an intermittent issue with the fuel pump. 

Edited April 1, 2016 by Fairtax4me

[1996BlackBauer]

I'll check that out, thank you. 

[1 Lucky Texan]

any correlation with rain/dew ? if so, try misting the plug wires down while idling - they may be cracked/shorting high voltage (they are 20 years old right?)

[1996BlackBauer]

So I grabbed the MAF out of the vehicle and opened it up, are we talking about the connection inside the housing, or actually at the board, I can't really see any cracks, although they might be smaller then my eye can see. 

 

 

 

 

Also, it doesn't appear to happen only when it is wet any or rainy outside, it happens on perfecty dry days as well, but I can check that out, just to be safe. 

[Fairtax4me]

Just the pins in that first pic where they come in from the connector. Only time I've actually seen cracks was when I wiggled the pins in the connector and saw one open up. Even then you can always see it. 

[ThosL]

I picked up a MAF unit on ebay new for $50--fixed the main problem on my sister's car.

[naru]

Check fuel pressure.

[idosubaru]

+1 on the MAF - i've seen those not cause a check engine light even though they're problematic (stalling, no start, poor running)

 

swap in another idle control valve or clean your existing one

check fuel pressure

 

why was the cam sensor unplugged?

 

if you plug the cam shaft position sensor in and drive it a week - you get no check engine light? 

[1996BlackBauer]

Thanks guys, I'll check all these suggestion out hopefully on Sunday after replaced the thermostat on my buddies EJ22. I'll keep the thread updated. So far I re soldered the connection on the MAF, and in the process of removing it I broke an elbow off the intake tube, so I am waiting for the JB weld to cure, and I'll at least start it up tomorrow, and see if it got any better.

 

Thanks a ton for all the suggestions though, I was also thinking it had something to do with the fuel Pump, plug wires, or the MAF, but wanted some input before I tackle anything else. While I was checking the car out I was wiggling connectors on sensor to see if it made it act up, and in the process of doing so I accidentally unplugged the cam sensor, turns out there was a small piece of dirt, or a rock stuck in the tab, which allowed it not to lock completely. 

[The Dude]

Do not run the starter motor for an extended period of time. The starter motor draws a lot of current but has no provision for cooling. It is possible to overheat, and ruin, the starter motor.

[1996BlackBauer]

Well time for an update, after repairing the intake tube, and soldering the connections at the MAF, I have run the car though about 2 30 minute running cycles, and about 15 miles of driving, I have yet to have a single sputter, misfire, or any other issue yet, I am going to take it to work tomorrow, which will be another 20 miles. the MAF may have actually been the issue. It even stsrts faster then before, which is awesome. I'm going to try and put 200 miles on it this week to see if anything happens, I'll update after that is complete. Thanks everybody for the input. 

[1996BlackBauer]

Update, it's still happening, it appears to happen less, but it's probably still in my head. 

 

[1996BlackBauer]

Well guys, I am breaking down and buying a fuel pressure gauge, but I cannot find an access port, so is the only way to get fuel pressure is with a T inline? Also while searching online I found different specs for what fuel pressure I should have, anybody got a Subaru service manual, or something similar so I know for sure...

[Fairtax4me]

Yes, have to T into the line by the filter.

 

You can rent a guage set with the T adapter you need at Advance auto. I've done that before. It's like $150 but you get the money back when you take the set back.

 

Should have about 35 psi at idle.

40-45 with the pressure regulator vacuum hose unhooked.

Edited April 7, 2016 by Fairtax4me

[1996BlackBauer]

Yes, have to T into the line by the filter.

 

You can rent a guage set with the T adapter you need at Advance auto. I've done that before. It's like $150 but you get the money back when you take the set back.

 

Should have about 35 psi at idle.

40-45 with the pressure regulator vacuum hose unhooked.

Very good thank you! I'm hoping to get everything hooked up either Saturday, or Sunday, I actually bought a Harbor Freight kit. I figure I could use it at home, and for work I'll buy a snap on one some day. It was only $18 with the coupon, so that's no big deal.

[sirtokesalot]

did you change the wires too or only the coil and plugs?

[1996BlackBauer]

did you change the wires too or only the coil and plugs?

Only the coil and plugs. I did check them for resistance, and they are within the allowable range. I also sprayed them with water to see if they are cracked and shorting anywhere, and they are not. I even took a good look inside the spark plug holes to see if I could find any burn marks of it shorting out in there and found nothing. Even though they are most likely the factory plug wires, they do appear to be in good shape. 

[1996BlackBauer]

Another update, sort of long video, but I do go into detail on what I did so I don't have to type as much. After the video I drove it for about 20-25 miles around town, and only had it slightly stumble twice, and one of the times was from a stop, so it might of been because of me not giving it enough gas. Let me know your thoughts, any input would be greatly appreciated. 

 

[1996BlackBauer]

Still happening, drove about 50-60 miles and it started doing it again, still not nearly as bad as it used to, but it continued to do it for about 2 miles then stopped again, and did it 2 more times for maybe 10-15 seconds... IDK what else could be causing this, this is really weird. 

[Fairtax4me]

Have you cleaned inside the three large connectors on the bell-housing?

 

There should be a ground point on top of the number 3 intake manifold runner. That's the main grounds for the ECU. Make sure those are clean and the bolt is tight.

 

Only other guess I would have is to check the connector at the ECU. Maybe the ECU is the problem?

I hate to blame that, but its possible.

[1996BlackBauer]

Have you cleaned inside the three large connectors on the bell-housing?

 

There should be a ground point on top of the number 3 intake manifold runner. That's the main grounds for the ECU. Make sure those are clean and the bolt is tight.

 

Only other guess I would have is to check the connector at the ECU. Maybe the ECU is the problem?

I hate to blame that, but its possible.

I'll check that all out, thanks, I almost feel like I am missing something,it is just an odd, and completely random problem, its really bothering me..

[1996BlackBauer]

OK, well plan of attack for tomorrow will be to check everything that Fairtax4me suggested, and also check the injectors, other then that, every single electrical item has been checked as far as i know. So I'll update once all of that is done.

[darsdoug]

Got another fuel pump assembly laying around that you can drop in the tank?

 

[1996BlackBauer]

Got another fuel pump assembly laying around that you can drop in the tank?

I do actually, I put it in already, and the issue is still happening. I have done just about everything under the sun, and it still happens.