2013 FR-S Misfire and Rough Idle

[aemravan]

Well... fingers crossed. Put the chains on and got the cover on. The fipg on the front cover was a pain.. had to take it off and re do it one time bc of a screw up. But motor is in the car and almost done. Hoping like hell I did everything right. Checked and double checked so I guess time will tell. Hoping to have it done tomorrow.

Sent from my SM-N950U using Tapatalk

[aemravan]

Well, the motor is in the car, fired it up last night, everything went awesome. Even made a couple of laps around the neighborhood to heat up the engine so that I could burp the coolant all the way.

Car ran for probably 30 some minutes, but had a strange rough idle. Didn't think much of it until I revved it up in neutral to about 4k rpm and kept it there for a bit to get some heat into the coolant.

Upon the deceleration the motor developed a weird metal clunking noise somewhere up top I think. Pretty mad and let down at the same time. I killed it and its sitting waiting to get diagnosed.

The noise sounded Cam related. Currently my theory is that the # 3 valve that originally dropped the rocker actually did get impacted slightly by the piston. When cold, it seated fine (as the leakdown test showed) but I am thinking when its hot maybe its got a little added friction from being slightly bent which allowed the damn rocker to fall off again? Only time will tell. But at this point it kind of turned into a nightmare build.

If the motor has to come out again I'll be pretty damn bummed but I don't see a way around it. My plan is to pull off the intake manifold and spin the motor by hand to see if all the valves are actuating. If they are, I have no idea whats wrong and will need to tear into it more. If one isn't, then I have a good lead. fml.

[RZNT4R]

Definitely disheartening, and judging by the pics at least, it doesn't seem like you could have been cleaner.

Was the noise there from the first turn of the crank or did it develop during the test drive? If you have the means to, check the PCM for trouble codes and Mode 6 for the misfire counters (before they set a code), It might not be on 3 and it might not be what you think. If (work) experience has taught me one thing it's to not despair and let the car speak to me. I've seen engines run so rough because of a single spark plug that I would have sworn they had rod knock.

[aemravan]

It developed after about 35 minutes of running after I revved it to 4k to warm up coolant while I park.

It was not showing any codes at the time, I had a blutooth scanner connected at the time.

Sounded like it came from the front. I took off the intake manifold now and so far looks like all the valves are activating... but too sunny to fully see. I'll check soon. And also didnt hear anything abnormal. Starting to think it may have something to do with the tensioner and chain slapping around ??

Sent from my SM-N950U using Tapatalk

[RZNT4R]

Originally Posted by aemravan

It developed after about 35 minutes of running after I revved it to 4k to warm up coolant while I park.

It was not showing any codes at the time, I had a blutooth scanner connected at the time.

Sounded like it came from the front. I took off the intake manifold now and so far looks like all the valves are activating... but too sunny to fully see. I'll check soon. And also didnt hear anything abnormal. Starting to think it may have something to do with the tensioner and chain slapping around ??

Sent from my SM-N950U using Tapatalk

If you bluetooth dongle supports it, check mode 6, it's often labelled as "onboard monitoring", it's a sort of pre-error code table of tests the ECM runs, with the pass/fail thresholds and test values. depending on the software you're using on your phone you may need to do a bit of translation, as the raw data is very obfuscated, but your software may present it in plain text.

If it's in the chains it'll be a toughy, this pain in the ass engine has no way to quickly check mechanical timing (that I'm aware of), your only hope would be to compare both banks in live data, like one bank using way more solenoid duty cycle to get the desired valve angle.

[edit]

I should add: Not that I want to reproach you for spinning it to 4K, that should be fine for these engines and it's probably not the cause of the issue, but rather it may have just uncovered it, going that fast is generally not needed. Put a stick between the seat and gas pedal and go for a smooth 1250-1500, it gives plenty of heat and it's not annoying to have it running like that while you check it over as it warms. An engine at 4K is loud and obnoxious, and it's hard to pay attention to little things while you're getting your ears blasted out.

Also, one question: Did you fire it up right after the reinstall, or did you crank it with the fuel system disabled to prime the oil system? that seems to have been a point of discussion in the recall failure thread, and I seem to remember seeing revised instructions about that floating around. It might be a quick test to drain a bit of oil and look for shiny bits

[aemravan]

The 4k rev was only quickly and after 30 minutes of running fine, at that point I felt pretty confident that all was well.

With that said, no, like an idiot I did not prime the motor with fuel off.. went right for start up. I saw the discussion in the other thread about that however, I don't think it's that likely to fail from that.. but I guess tmrw will find out. I figure it's much quicker to pull the motor to see what's wrong than try and dig in with it in the car. I spent an hour trying to take off the valve cover with no luck.. could have had the motor out on about that time

Sent from my SM-N950U using Tapatalk

[RZNT4R]

Originally Posted by aemravan

I spent an hour trying to take off the valve cover with no luck.. could have had the motor out on about that time

The Subaru Way(tm)

[aemravan]

Well, got quick as hell pulling motor. 2 hours start to finish.

Now...with that said... I dont know whether to laugh or cry... all rockers and valves are in place and look seated just fine...

But on my way to start taking off the front cover, I discovered that this upper idler pulley seems to have a bad bearing.. I could barely turn it by hand..... which now that I think about it... I saw the belt tensioner jumping around ALOT when I was hearing the noise... so... with that said... could this really be the cause of the knocking I heard ?? Oil looks pretty darn clean and I'm not sure if i want to pull the front cover off if theres no need....

Sent from my SM-N950U using Tapatalk

[Ultramaroon]

I'm surprised that you didn't hear a telltale loud whir of the failed bearing. It would be spinning way too quickly for it to sound like a knock. I could picture a scenario where you might hear it slip whenever the label or some stitched part of the belt passed over it.


I recommend putting it back together and testing again.

[aemravan]

I think the problem is that I installed the spacer between the bolt and bearing backwards and it jammed the bearing it. It got hot to the point where it oozed its lubricant all over the inside. It wasnt a typical failure that would have whined first. And I think the knock may have even been the tensioner knocking back ?? The bearing was hard to turn and I saw the tensioner jumping pretty violently.

With that said... any idea if the 2 pulleys are the same ? I'm looking for a replacement but all diagrams I'm finding are for a single pulley..

Sent from my SM-N950U using Tapatalk

[RZNT4R]

Originally Posted by aemravan

Now...with that said... I dont know whether to laugh or cry...

Laugh it off. You're going to remember this for years, so you may as well give up on taking yourself seriously and laugh. That way you'll be able to regale others with the story of that time you pulled an engine to replace the most easily accessible idler pulley in the world.

[Ultramaroon]

Originally Posted by aemravan

I think the problem is that I installed the spacer between the bolt and bearing backwards and it jammed the bearing.

Shit. I wondered about that. Here's the up side. You see exactly what you did. It wasn't catastrophic so it was an inexpensive lesson. I've had MUCH more expensive ones.

https://parts.subaru.com/a/Subaru_20...10-094-01.html

https://parts.subaru.com/p/Subaru_20...3770AA070.html

They're the same part. And what @RZNT4R said.

[aemravan]

Thanks fellas. Definitely funny as hell on day two lol. Besides. I got pretty good at this with the help of my fiance. Motor is back in and car is just about good to go. Just waiting to pick up the pulley tmrw am from Toyota and have one more coming just in case from Amazon.

Sent from my SM-N950U using Tapatalk

[aemravan]

Well guys... I certainly pulled the motor to replace the easiest idler pulley ever. But I dont care lol. The car is on the road. Did 2 test drives and so far so good.. ready to get pre inspected so then i can finish installing all new panels and do a final inspection. Currently waiting to flash the stage 1 tune via oft so help out with the new airbox and exhaust modifications (check out the new carbon additions to the inside too ).

Sent from my SM-N950U using Tapatalk