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Old 04-28-2021, 10:27 PM   #1
D-tained1
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Default Engine stutter randomly after valve covers

So while driving or even idling the engine will basically turn off, sometimes it will turn back on by itself other times it's a complete stall.

Recently I had some leaky valve cover gaskets and I replaced those. Obviously the battery was removed so this could be a learning thing but idk if that's a thing. Otherwise I also did an oil change and I used a new type of oil 5w20 (I thought it was 5w30 when I ordered it but I guess not)
So I'm not sure if that could be the issue or if this is completely unrelated to the changes I just made.

Im running a cobb stage 2 map with 3" dp/exhaust and a cobb cold air intake otherwise stock. Those mods preexist the issue though
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Old 04-29-2021, 11:28 PM   #2
D-Rodman
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Default Engine stutter randomly after valve covers

Hopefully you won’t have a spun rod bearing before you figure out the issue. Did you replace the valve cover gaskets yourself ?
Did the gas station shop around the corner do the job ?
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Old 04-29-2021, 11:37 PM   #3
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5w20 probably isn't going to give you much protection....what kind of oil preasure are you even seeing with it?

After you've got a proper weight oil back into it, I would start by double checking the coilpacks are fully seated onto the sparkplugs, and coilpack connectors are clipped in fully.

EDIT: AND that the coilpack connectors are plugged to the correct coilpacks... the white clips go to the front two cylinders.

Last edited by T-37; 04-30-2021 at 11:03 AM.
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Old 04-30-2021, 02:59 AM   #4
moral hazard
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Probably a vacuum line is not connected somewhere causing a vacuum leak.

Check A/F learning and correction values.
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Old 05-01-2021, 02:24 PM   #5
D-tained1
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Quote:
Originally Posted by D-Rodman View Post
Hopefully you won’t have a spun rod bearing before you figure out the issue. Did you replace the valve cover gaskets yourself ?
Did the gas station shop around the corner do the job ?
I did the valve cover gasket job. Unfortunately it's the first time I'm doing this.

As an update I noticed the stall/stutter seems to be linked to the thermostat opening and closing.

At first I was in a parking spot the engine stalled and the engine heat spiked for a second.
While driving on the highway today I noticed a flicker of the check engine light again a quick spike of the heat increasing and the sound of the thermostat popping open.

Am I wrong to assume there's some rtv or something mixed in with the oil?
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Old 05-01-2021, 03:08 PM   #6
D-tained1
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Quote:
Originally Posted by T-37 View Post
5w20 probably isn't going to give you much protection....what kind of oil preasure are you even seeing with it?

After you've got a proper weight oil back into it, I would start by double checking the coilpacks are fully seated onto the sparkplugs, and coilpack connectors are clipped in fully.

EDIT: AND that the coilpack connectors are plugged to the correct coilpacks... the white clips go to the front two cylinders.
Not sure how I can check the oil pressure, I guess I'll have to see if the accessport has a readout. Otherwise the spark plugs and coil packs are set, I torqued them down to 17/18 because I kept seeing 15-20 ft lb.

White is in the front, and black is in the back. I made sure to verify that when after the valve cover gaskets the car wouldn't start properly. After I adjusted them it started up. I'll order some oil and I guess wait until tht comes in
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Old 05-04-2021, 08:42 PM   #7
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So quick update. I changed the oil and there was one or two pieces of metal but they didnt look shiny and afaict dont seem to be the engine.



I used amazonbasics 5w30 high mileage full synthetic based on a youtube channel that was reviewing multiple types of oils.


In terms of the stutter its still there. Looks like the thermostat may not be involved like I originally thought.


From what i can tell after driving it today was that it doesnt occur as often when the engine is cold. I let the car idle while cleaning up and didnt see it happen once, I also tried to rev it from the engine bay to see if i could get it to happen and nothing.

After I drove it and then let it sit maybe 5/10 minutes it got way worse (especially at idle) and low speeds (driving 5-20mph down sideroads). This is similar to what happened when i went to subaru parts to get an IAC gasket, in that the problem got worse when leaving subaru then the initial drive there



All i can tell at this point is that when it goes to misfire/stutter the engine will turn off for like a split second then sometimes it turns back on like i initially mentioned. Also the accesport powers off so i guess the car loses power while it happens. Lastly the heat gauge (on the instrument panel) seems to fluctuate as it happens but will stabilize after and before in the center as normal.


If anyone can give me some troubleshooting steps id be grateful as im at a loss at this point. I'm going to try to remove the valve covers again this weekend to see if I can see anything out of the ordinary but I dont know what else to keep an eye out for.



Otherwise i need to figure out a way to get the IACV screws off so I can change that. I doubt my stutter is related since it only started after the valve cover gasket job and the stutter occurs while driving (20-50mph although less frequently) but for the cost of the gasket its good maintenance.


Lastly i have a p0037 code that returns instantly, I didnt bring it up initially since it appeared before the valve cover job and didnt think it could cause this issue. But the sensor is def the problem since the code re-appears almost instantly after reset it. this is just and fyi though as i doubt its related.
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Old 05-05-2021, 12:29 AM   #8
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P0037 is pointing you to the problem.
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Old 05-06-2021, 08:33 PM   #9
D-tained1
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Originally Posted by D-Rodman View Post
P0037 is pointing you to the problem.
Changed the rear o2 sensor with a denso replacement. I cleared the cel. The light is now off so I can tell you that the issue is a misfire, but I don't have a code.

The code flashes and then disappears. When driving on the highway about 6 miles 55 mph in 4th it didn't happen once (using cruise control). When I had to merge and slowed to like 20-30 it happened once or twice.

I still think there's more crud in the oil so I'll probably get more and try changing it and the filter again this weekend. Fingers crossed
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Old 05-06-2021, 09:11 PM   #10
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Quote:
Originally Posted by D-tained1 View Post
Changed the rear o2 sensor with a denso replacement. I cleared the cel. The light is now off so I can tell you that the issue is a misfire, but I don't have a code.

The code flashes and then disappears. When driving on the highway about 6 miles 55 mph in 4th it didn't happen once (using cruise control). When I had to merge and slowed to like 20-30 it happened once or twice.

I still think there's more crud in the oil so I'll probably get more and try changing it and the filter again this weekend. Fingers crossed
on the 16bit ecus it takes alot for them to show misfires
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Old 05-06-2021, 09:52 PM   #11
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I know the YouTube channel you are referring to for the oil. It's project farm or something like that. The one big thing you or him didn't take into consideration is fuel contamination. And subarus are known for that. There's a reason we use Diesel engine oil like rotella t6 5w40. I even brought that to the YouTuber who made that video
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Old 05-07-2021, 12:40 AM   #12
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Never had good luck with denso replacement sensors, oem only for me. Yes, I know Denso makes the OEM.
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Old 05-07-2021, 04:21 PM   #13
D-tained1
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Quote:
Originally Posted by Brother EddieJ. View Post
I know the YouTube channel you are referring to for the oil. It's project farm or something like that. The one big thing you or him didn't take into consideration is fuel contamination. And subarus are known for that. There's a reason we use Diesel engine oil like rotella t6 5w40. I even brought that to the YouTuber who made that video

Ahh, I personally have never used the Rotella t6 in my car, because of the fact it was diesel oil, but I have seen that people swear by it on here. I guess maybe i should try it at some point and see what happens.

In terms of the main thread I realized that i did drop one of the spark plugs when I pulled them out (the video doing the valve covers said to pull them). Luckily I know it was only the spark plugs on 1/3 so I know which side my issue is most likely on since i only pulled 2 total plugs. So I am also ordering replacement plugs since I didnt check the gap, although i can probably check the gap i dont know when they were last changed.

Hopefully the spark plugs turn out to be my issue since going through the whole misfire thread does not sound like fun.

Last edited by D-tained1; 05-07-2021 at 04:26 PM.
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Old 05-09-2021, 12:24 AM   #14
D-tained1
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So i have some news. I was driving today and I got 5 cels. All 4 cylinders, and a p0000 generic misfire code.

Then ups finally delivered the spark plugs so I swapped them out.

After driving the stutter is much better. It went from stalling out while idle to only stuttering when I drive over bumps on the highway.

So the issue is still there but now it's only happening when I hit a bump, not all but some. Otherwise I cleared the 5 codes from earlier and I did have a misfire code for cylinder 2 and 4 as well as the p0000 generic misfire code. So I'll check the wiring on those coil packs. I will say I doubt they are bad since it's only happening over bumps now.

I read that it could be a loose ground or batter connection so I made sure to tighten down the battery terminals after I did the plugs so, I guess I need to find out where else the car is grounded as well
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Old 05-12-2021, 11:01 PM   #15
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Did you replace the half moon seals? I would go back through your work and make sure everything is buttoned up. You most likely have a vacuum leak on something you worked on or bumped into while working. Need to check the valve covers and all vacuum hoses.
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Old 05-17-2021, 08:27 PM   #16
D-tained1
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Did you replace the half moon seals? I would go back through your work and make sure everything is buttoned up. You most likely have a vacuum leak on something you worked on or bumped into while working. Need to check the valve covers and all vacuum hoses.
I did not replace the half moon seals as the video guide I was using said that unless they seem loose there isn't a great reason to remove and replace.

I will say the issue still happens and the misfires are on all 4 cylinders again (w/ the p00000 code) but not as frequently. I have seen that a vacuum leak could be the culprit with the misfires but I haven't really had much time to look into it.

Even though the issue still occurs I feel like the car is way better then where it was since I changed the spark plugs
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