Very Strange Misfire/Stumbling SR20 (searched)

[SolaraOnBronze]

I know there a lot of threads on the subject, but bear with me...

So here is the deal- I replaced all of my turbo and exhaust gaskets last week and the car ran great after that. Here is my setup:

SR20DET BlacktopIntake, Exhaust, Front Mount, Stock Turbo, Walbro pump, etc.

The car ran and drove great after that with no issues at all. I drove to my in-law's house, which is about 90 miles, and when I got off of the freeway I noticed the car starting to shake. The exhaust note changed and started to sound like a subaru, very rough and louder than it was before. The car idled rough and was shaking, but didn't seem like it wanted to stall out or anything.

Oil pressure, oil temp, water temp, and vacuum were all good. The car could go into and hold boost just fine, but was extremely sluggish and bogging, in addition to still sounding like a subaru. Got to where we were going, shut it off, and let it for about an hour. When we came back to the car, it started right up and idled normally. The issue seemed to have gone away.

When I got it home (about a 5 minute drive from where we were) I realized when that I had only finger tightened the bolts on the air filer when I replaced the turbo gaskets (FAIL). Only one was left and it had started to back itself out. I went and got new bolts, tightened all 4 up, started the car- and everything was fine.

I drove the car for an hour to a big meet the next day and everything was great- the car pulled hard, idled right, sounded right, and felt great- no issues at all whatsoever. When I went to leave the meet, I had someone take a couple of pics for me. I let it idle for about 5 minutes, and the problem started all over again- almost like someone flicked a switch. Rough idle, subaru exhaust note, etc. I drove it home an hour with it running like crap and it never went away. I checked the air filter to see if it was loose like it had been previously, but everything was still tight and good to go.

I guess I'm just wondering what sort of things could come and go randomly like that. It seems like the car is only running on 3 cylinders if I had to guess- it take a bit to get up to speed and the car almost has to be in boost to go 75-80 on the freeway. I have not replaced the spark plugs since I have owned the car- could that cause an issue like this? My first plan of attack is to pull each plug to see if they are all getting spark.

Can anyone tell me how to check the injectors to see if I have a bad one? I check the resistance, correct? Any input or feedback is welcome, I am going to get the car back to my place today and start trying things after work tomorrow. Thanks in advance!

Damon

[Chris28]

Plugs and wires. My car did the exact same thing. New plugs "fixed" it, but it was really the wires.

Change both!

[SolaraOnBronze]

I see you are a KA-T... are there really wires to replace on the SR? Or in that case it would be a bad coil pack(s)? Thanks for the input though, I'll pull the plugs tomorrow and have a look!

[SolaraOnBronze]

Well, I replaced the plugs yesterday with NGK Iridium IXs, and no luck. My next guess is a bad coil or coils...

[Bumnah]

It's def. in the ignition. From the description I think it's a coil pack failing.

Look at the old plugs to see if one looks different than the others. Check your grounds as well. Perhaps the coilpack harness ground came undone.

[killernoodle]

While the engine is running poorly (Idling funny/sounding like a subaru):Pull each plug on each coil pack while the motor is running. If the motor changes sound or stops, that coil pack is fine. If you pull the plug and nothing happens, you have identified the bad coil.

[Chris28]

I see you are a KA-T... are there really wires to replace on the SR? Or in that case it would be a bad coil pack(s)? Thanks for the input though, I'll pull the plugs tomorrow and have a look!

Lol I'm dumb. As everyone before me has said, it is most likely a bad coil pack. Forgot about the whole sr/coilpack thing haha.

[SolaraOnBronze]

While the engine is running poorly (Idling funny/sounding like a subaru):Pull each plug on each coil pack while the motor is running. If the motor changes sound or stops, that coil pack is fine. If you pull the plug and nothing happens, you have identified the bad coil.

This is good advice, thanks! I'm going to try this next and see what happens.

[mattblancarte]

Pulling the plugs helped identify that my #1 cylinder wasn't firing around the time I bought my car.

Turned out to be a bad injector clip.

[adrianfromthecastle]

sounds like injectors to me...

should probably check / clean those out

[Bumnah]

sounds like injectors to me...

should probably check / clean those out

Possibly, but because it doesn't happen all the time, and it sometimes happens after the car has been running. I'd lean towards an coil overheating. I mean it is multiplying the voltage tens of thousands of times per fire.

[SolaraOnBronze]

As soon as I solve the problem, I'll post it up for everyone. I appreciate the input guys!

[SolaraOnBronze]

Well, it isn't a coil. I started the car and pulled them one by one today, and the #2 cylinder is not firing (Assuming the cylinder numbers go from 1 to 4 with 1 being the closest to the front end.) I swapped the coils between the #1 and #2 cylinders and it was still #2 that was not firing.

So, back to the drawing board again. Should I move on to testing the injectors? How do I go about testing an injector to see if it is bad? Thanks so much for the feedback so far, it has helped me out a lot!

[1sikS13]

same test as the coil pack test. just unplug them one by one. till you find the one that makes no change