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

[wotdsm]

This sounds stupid but go through every sensor that regulates driveability (crank and cam position, MAF/MAP, coil, coolant temp, O2, etc.) and make sure they're 100% plugged in securely and the locking tab that keeps them plugged in is intact and locked.

I was chasing a random misfire (each cylinder would randomly misfire throwing a CEL and the car would buck and hesitate randomly) for a YEAR on my forester. I replaced and tested everything under the sun... Eventually I went to test the OHMs on my crank position sensor (the one sensor I did not test) and the pigtail came unplugged with my pinky. First thought was "no it couldn't be that simple..." Tested the sensor anyways and it was fine, plugged the pigtail in 100% securely and voila, the issue I spent a year losing sleep over was cured... Electronics can be tricky if they don't have a completely reliable signal and the pig tails aren't completely and securely connected and my symptoms mirrored yours, some days the car would run great, other days it misfire and buck under load. 

[1 Lucky Texan]

yeah, I even read of a guy getting misfires due to debris on the crank position sensor - cleaned it off and the car ran fine.

[1996BlackBauer]

I will be sure to do that, thanks again! When I replaced the crank sensor it had a bunch of junk on it, the problem got only slightly better, but that had to be part of it.

[1996BlackBauer]

Bad news guys, I did everything I said I was going to do, and after only 10 minutes of running it was back at it again. the connectors at the back of the block where pretty clean, I did however find 2 wires that had the insulation rubbed off of them, after cleaning everything up, and throwing some electrical tape on them, I found nothing else wrong with the wiring harness. The ECM looks to be in good shape with no signs of water intrusion at or around it what so ever. The Injectors all tested at 11.5 ohms, which the spec is 11-12 ohms, so those are good. I also did the not so scientific shake test at all of the connectors I could find, and all where secure. Lastly I checked the ground and that was tight and secure as well. I still can't believe it is the ECM, there HAS TO BE something else I have missed, unfortunately I do not have a spare '96 ECM laying a around I only have a '93 1.8 ECU, so I cannot swap and see if that is the issue.  Any other input would be greatly appreciated, I just want to drive the darn thing, instead of looking at it. this is really getting to be annoying. 

[avk]

Could be a malfunctioning IAC valve, just to add to the list.

[1 Lucky Texan]

I re-read the thread - does it seem to only happen after the car warms up? wotdsm mentioned the coolant temp sensor (might be one 3 wire device onyour cat, if not, it's the 2 wire one, not the single wire temp gauge sender.

 

anothet thought, hook a vacuum gauge up and see what it does before and after the problem exhibits itself. Maybe a valve is sticking or ....?

[1996BlackBauer]

Could be a malfunctioning IAC valve, just to add to the list.

I have cleaned that, and it appears to be working just fine, can that cause misfire like symptoms while driving at higher RPMs?

 

I re-read the thread - does it seem to only happen after the car warms up? wotdsm mentioned the coolant temp sensor (might be one 3 wire device onyour cat, if not, it's the 2 wire one, not the single wire temp gauge sender.

 

anothet thought, hook a vacuum gauge up and see what it does before and after the problem exhibits itself. Maybe a valve is sticking or ....?

You know what, I have not checked the temp sensor, it does also appear to happen after the car warms up, it ALWAYS got to operating temps before it ever started doing this. I'll check the specs for it on Alldata, and test mine, I'll report back. Also, I've needed an Excuse to buy a vacuum gauge, so I will also do that as well. Unfortunately this issue might have to sit on the back burner for a little bit, my best friend dropped of his '95 Impreza for a motor swap that I finally just got all the parts for, along with some JDM suspension, and brake components, I'm hoping for a 2 week turn around, including waiting for the clutch and new light weight flywheel. But in my free time I'll be trying to get mine running good again.   

[mikec03]

First of all I want to express great sympathy for your problem.  I have been maintaining multiple 2.2 engines for the last 20 years.  And intermittent problems are the worst kind to solve.

 

Second, these cars are so old that it is much more economic or your money and time to just go the you-pull-it or carparts.com and just get a replacement.  

 

Third, now go get a complete replacement for you MAF.  It doesn't matter what a grand job you did with your soldering iron, it's only $30 to get a complete replacement.  As stated by earlier posters, the MAF is a problem for old subarus.  The same goes for the throttle position sensor or IAC and or even the whole throttle assembly if you can bargain it down to a low cost.  By the way, the TPS is difficult to calibrate just so you know.  Search for procedure.  

[wotdsm]

Our coolant temp sensors can cause all sorts of weird issues when they fail... I agree with testing that. 

PS- if it does test bad, please for the love of God don't buy an aftermarket one. My friend has an 02 OBL with the EZ30 and he replaced his with THREE aftermarket ones that were all junk upon install. The auto parts store actually gave him a hard time about exchanging them... And actually by the third one they told him just to get a used one or new OEM one.  

Edited April 18, 2016 by wotdsm

[1996BlackBauer]

Thanks for the input guys, hoping to have some free time to mess around with the car this weekend before I head up to Jefferson for the swap meet. I looked up the MAF and found a new one for $46, from a company called Replacement? IDK how good it is, but it is in my budget for this car. as far as the temp sensor goes I can probably get to that this week, I just have to remember my volt meter and temp gauge from work. I'll continue to leave updates with what I do and find. Thanks again for the tips, Normally I am not one for just throwing parts at a car without good reason, but if the MAF go bad all the time, it's worth a shot I guess. 

[1996BlackBauer]

Unexpected update, Well after relaxing for a bit and eating, I began rummaging through my garage, and I was able to pull out a full air box, with a MAF sensor off of my buddy's '93 Impreza, which ran perfectly fine until he gernaded the trans, and decided to ditch the car due to Structural rust issues. so I popped it on my car, and let it run, now just as a reminder EVERY time I just let the car idle in my driveway within 15-30 minutes it will start having the issue. I let the car run for almost 2 hours, with absolutely no problems at all. I was outside the whole time too, I was taking things off my buddy's car for the engine/suspension swap. Sooooo, MAYBE? its fixed? I'm going to drive it the rest of the week to find out, usually 2 days to work, and the problem comes right back, so We'll see, I'll update if and when it happens again, or at the end of the week.  

 

thanks for everybody's input.

[wotdsm]

Curious if after a few days if the problem still has yet to replicate itself. OP?

[1996BlackBauer]

I have only driven the car for 60 miles, but I have yet to have an issue. It would appear that the new to me MAF sensor fixed my issues. Still not going to go any any big trips with it until I put a few hundred miles on it, but I'm feeling pretty confident. The last few times it happened within an hour or less of sitting in my driveway idling, or less then 20 miles of driving. I can only assume that the solder joints where either not fixed by my soldering, or that the chip in the MAF took a crap due to age.Either way I can't thank everybody enough, I am very thankful for all the input. now if I could only get some front fenders for my car I would be happy, anybody got any? lol.

[Fairtax4me]

The MAF solder joint fix is only a sometimes cure. And actually it only really fixes the one set of symptoms that I've seen. Your's had a different issue, but still could certainly be caused by a failing MAF sensor. 

 

Hopefully you'll be back in a weeks or to saying she's fixed! 

[1996BlackBauer]

The MAF solder joint fix is only a sometimes cure. And actually it only really fixes the one set of symptoms that I've seen. Your's had a different issue, but still could certainly be caused by a failing MAF sensor. 

 

Hopefully you'll be back in a weeks or to saying she's fixed! 

Good to know, thanks for the input. Well I have now driven about 240 miles without a single misfire, loss of power, bucking, or stumbling, it actually appears to be driving WAY better then it ever has, it almost a new car. I am almost curious as if the MAF was having issues since I have owned the car, and it only really got bad more recently. when I first got the car it was super sluggish, it BARELY got out of its own way, and that was only if it was to the floor. Now is is actually quite peppy.  I still can't thank everybody enough, it feels great to be able to drive my car again. now that I have fixed most of the oil leaks, the running issue, its time to prep it for a few rally cross events and have some fun, like I was originally going to do.