LGTMKE Posted March 21, 2018 Share Posted March 21, 2018 Hey guys, thanks for the help! I'm a little shaky on engine knowledge so if I use the wrong term please correct me. 2011 GT One day when I was accelerating hard onto the freeway, the car started jerking violently at around 4k RPMs, like it was going from full throttle to a fuel shut off, then the check engine light came on. Brought it into Subaru dealer, they said it could be... 1. valve related since they found that my valve clearance on all 4 cylinders was off, but it was worst on valve 4. Further, the code that they pulled for the check engine light was P0304- Cylinder 4 Misfire Detected... 2. or it could also be that I needed a new cylinder head on cylinder 4. They charged me up the ass for the diagnosis (about $800 all said and done), and couldn't guarantee me either the $2,200 valve clearance adjustment or the $4,500 valve clearance adjustment and new cylinder head repairs would fix the issue. Naturally I wanted a second opinion and brought it to a local mechanic. He confirmed that the valves needed adjustment ($2,200 job), but wasn't positive this would fix the issue. Though he did say he couldn't find anything else wrong with the car so by process of elimination that's the only thing he can see helping. I've sunk in almost a grand into the thing just to hear my valves are out of adjustment, and that adjusting them only might fix the issue. I don't wanna sink in even more money for 3rd and 4th opinions but I'm out of options. If I go ahead and do the valve adjustment I'll have paid $900 in diagnosis plus $2,200 for the adjustment amounting to $3,100 spent and I could end up still having the issue, leading to more money spent on more diagnostics and work. That's a lot of money to me right now. Has anyone else had this issue? Should I just go ahead with the valve adjustments and hope it fixes this? Anyone know someone who has had this problem or knows this engine inside and out I can contact? THANK YOU! Link to comment Share on other sites More sharing options...
LGTMKE Posted March 21, 2018 Author Share Posted March 21, 2018 I should add - the car drives like butter otherwise. Smooth idle and startups, and can even drive moderately hard without any issues. It's only under heavy throttle/load that this issue happens around 4k + RPMs Link to comment Share on other sites More sharing options...
Rbaquero08 Posted March 21, 2018 Share Posted March 21, 2018 I should add - the car drives like butter otherwise. Smooth idle and startups, and can even drive moderately hard without any issues. It's only under heavy throttle/load that this issue happens around 4k + RPMsI have experience this before, in my case I took the coil pack from cylinder 4 and swapped to different cylinder and tested it again and it switch to that cylinder.. in other words my issues was bad coil pack. U can start with that since testing it like I did is free lol Link to comment Share on other sites More sharing options...
LGTMKE Posted March 21, 2018 Author Share Posted March 21, 2018 I'm a complete idiot compared to the average person on here it seems, I don't even know what a coil pack is. Is this something I can google and do myself or should I have someone do it for me? Link to comment Share on other sites More sharing options...
cww516 Posted March 21, 2018 Share Posted March 21, 2018 These cars are what's referred to coil-on-plug, which means we don't have spark plug wires between the coils (or distributor on older cars) and the plugs like you may have seen in the past, there's a coil pack that plugs right on to each spark plug. There's a single electrical connector on each one and a bolt holding it in place, but aside from being a bit fiddly (there's one specific way you have to spin it to get it out of the car), they're pretty simple to change. I'd pull coil #4 out and take a look at it- the outside should look like a bunch of this metal plates stacked up, but if the plates are rusting to the point where they're peeling apart, that's a good sign that the coil is bad. If that's the case, swap #2 and #4 and see if the misfire follows, and if so, go ahead and replace that coil pack. Link to comment Share on other sites More sharing options...
LGTMKE Posted March 21, 2018 Author Share Posted March 21, 2018 I've done some browsing on this forum and it seems like some common diagnostics are to... 1. Check the spark plugs (gotta start somewhere) 2. Check coil pack - switch #4 and another to see if problem follows 3. Double check injectors and also swap around to see if problem follows 4. Check for valve clearance and burnt valve (cylinder #4 head known to run lean and burnt exhaust valves seem to happen on #4 first caused by improper valve adjustment) 5. Test ringlands by taking the oil cap off (while it's running) and look for puffs of smoke. That's almost a positive diagnosis for ringland/bottom end failure 6. Get a new short block *wipes tear away* Based on what I DO know about my car and all these tips it seems like I should adjust my valves regardless, especially since #4 is the most off, and then test my plugs, coil pack and injectors. Link to comment Share on other sites More sharing options...
Starks Posted March 21, 2018 Share Posted March 21, 2018 Coil #4 is the hardest to do if I'm not mistaken. You could do it yourself but it's definitely a pain in the ass. You'll spend most of the time trying to get the pack off and out. When I changed that plug I never fully removed the pack from the engine bay just slid it out the way just enough to do the plug. Hope you have Trump hands! Sent from my SM-G955U using Tapatalk Link to comment Share on other sites More sharing options...
dgoodhue Posted March 21, 2018 Share Posted March 21, 2018 I've done some browsing on this forum and it seems like some common diagnostics are to... 1. Check the spark plugs (gotta start somewhere) 2. Check coil pack - switch #4 and another to see if problem follows 3. Double check injectors and also swap around to see if problem follows 4. Check for valve clearance and burnt valve (cylinder #4 head known to run lean and burnt exhaust valves seem to happen on #4 first caused by improper valve adjustment) 5. Test ringlands by taking the oil cap off (while it's running) and look for puffs of smoke. That's almost a positive diagnosis for ringland/bottom end failure 6. Get a new short block *wipes tear away* Based on what I DO know about my car and all these tips it seems like I should adjust my valves regardless, especially since #4 is the most off, and then test my plugs, coil pack and injectors. It is pretty likely one your coil packs. If you haven't done your spark plugs, its probably a good idea to replace them as well. (The maintenance interval is every 60k). I think every faulty coil pack some has notice the coil look visually bad (cooling fins expanding from rust). If the coil looks bad you may not need to bother seeing the problem follow the coil. I am not sure how one would adjust the valves with a DOHC boxer engine, other than check specs, but I am think you need to pull the motor to remove the cams and access them. Link to comment Share on other sites More sharing options...
LGTMKE Posted March 21, 2018 Author Share Posted March 21, 2018 Thanks everyone, seems like the coil packs are where I should start. Again, I'm not very well versed on engines so I may be using the wrong term, but when the dealership was diagnosing the issue I'm pretty sure they measured the valve clearance and all of my valves were off, particularly my 4th one. They spent the better part of a day in labor to look at all this. In my research it seems like a burnt valve, especially in the 4th one, can occur and then you run into a new array of problems. Given mine are all out of spec and the 4th is the worst, I think I should get those adjusted now anyway to prevent further issues, even if they aren't the direct cause of my primary issue. Thoughts? Also how much time would you guys think it would take any midway decent mechanic to check out all my coil packs and swap them around to see if problem follows? Link to comment Share on other sites More sharing options...
cww516 Posted March 21, 2018 Share Posted March 21, 2018 Makes sense how long it took for them to measure clearances- 4 valves per cylinder, 4 cylinders, and not a whole lot of room between the heads and the subframe. Any chance they gave you the clearance measurements they got? If you're just slightly out of spec, it may not be anything to freak out about. I'm not completely convinced that slightly out-of-spec valve clearances would cause the issue you're seeing, though, I'd think you'd see that misfire throughout the RPM range. Higher RPMs mean more load on the coils, though, which means more heat, and if they can't dissipate that heat, they'll start to flake out. As far as time to mess with coil packs, that'll depend on how much time they've sent working with coil-on-pack Subarus and how much of a strategy they have, as well as how skinny their forearms are. I can get all 4 out without having to remove anything else from the engine bay, but standard procedure is to remove the air box and the battery. I wouldn't be shocked if it was 2-3 hours all-in to remove and reinstall all 4 coil packs, probably about the same to swap 2 of them and see if the issue follows it. If that one coil pack is noticeably bad, though, I'd just throw a new coil on #4 and see if that fixes it. Link to comment Share on other sites More sharing options...
LGTMKE Posted March 21, 2018 Author Share Posted March 21, 2018 CWW - They did, I have to find the sheet they gave me or will need call and ask. Even so, I remember them saying they were all relatively ok and even #4, the most out of spec, wasn't alarmingly off, just the most off. It isn't misfiring throughout the rpm range, and I can even get to redline as long as I am not putting it under harder load / acceleration > issue ONLY occurs when at/near full throttle at 4k+ rpm. I have thick forearms and am still a padowon at engine stuff so I'd need someone to do it for me. Subaru would do be able to do it, but would likely go the longest route possible and charge about $112 an hour for labor. A local mechanic might do it as efficiently as possible but wouldn't really be familiar with the process. Know any trustworthy and knowledgeable mechanics around the greater Milwaukee area? Link to comment Share on other sites More sharing options...
coco26 Posted March 22, 2018 Share Posted March 22, 2018 I'm finding that Subaru as a company likes to throw valve adjustments at a lot of issues, which don't have any effect in most cases. I'd definitely pursue the coil swap first. In my opinion, any decent mechanic should be able to handle it. A coil pack is a coil pack no matter the engine. The only special abilities needed are good elbows. Link to comment Share on other sites More sharing options...
Becks1818 Posted March 22, 2018 Share Posted March 22, 2018 Had the same issue twice. Both times it was coilpacks. Link to comment Share on other sites More sharing options...
dgoodhue Posted March 22, 2018 Share Posted March 22, 2018 I'm finding that Subaru as a company likes to throw valve adjustments at a lot of issues, which don't have any effect in most cases. Maybe it's a way to ease the customer into broken ringlands, burnt valves and blown headgaskets Link to comment Share on other sites More sharing options...
FLlegacy Posted March 22, 2018 Share Posted March 22, 2018 Have we had a 5th gen yet with ringland issues? I know we have a couple of headgasket leaks, a couple of burnt exhaust valves, and a couple bottom end issues...we need to track this stuff. If I am not mistaken it seems our engines are better off than most other boosted ej motors. Link to comment Share on other sites More sharing options...
Shadow_419 Posted March 22, 2018 Share Posted March 22, 2018 Have we had a 5th gen yet with ringland issues? I know we have a couple of headgasket leaks, a couple of burnt exhaust valves, and a couple bottom end issues...we need to track this stuff. If I am not mistaken it seems our engines are better off than most other boosted ej motors. Seized oil control ring for me and burnt exhaust valves. I do remember reading about a ringland issue when I first joined. One of the early owners. Link to comment Share on other sites More sharing options...
dgoodhue Posted March 22, 2018 Share Posted March 22, 2018 Have we had a 5th gen yet with ringland issues? I know we have a couple of headgasket leaks, a couple of burnt exhaust valves, and a couple bottom end issues...we need to track this stuff. If I am not mistaken it seems our engines are better off than most other boosted ej motors. I think their was one 5th Gen with a ringland issue. I remember seeing of failed short block with a picture of a piston that showed signs of significant detonation. I think the 5th Gen are doing better than other boosted EJ25, but it maybe due to the low production numbers. If it is improved I would think it due to the equal length headers, lack of mods and it seems like this community only uses a handful of quality tuners (as oppose to the large number of tuner who do 4th Gen LGT/WRX and may have few questionable tuner in the mix). 5th Gen's also don't seem to have the turbo failures the 4th Gen LGT have either. Link to comment Share on other sites More sharing options...
FLlegacy Posted March 22, 2018 Share Posted March 22, 2018 Maybe Subaru finally opened up the ring gap as well. Link to comment Share on other sites More sharing options...
ahkenaden Posted March 22, 2018 Share Posted March 22, 2018 Just had this issue myself, started after applying an AP tune. Was the #4 cyl coilpack. Thing was cracked out like a Detroit hooker... Link to comment Share on other sites More sharing options...
LGTMKE Posted March 22, 2018 Author Share Posted March 22, 2018 Alright guys - went by my mechanic's shop last night to go over all of the possible issues I described here in my last reply - he thinks it isn't the coil pack, injectors, ringlands or even the exhaust valve clearance that is off. He seems like a very knowledgeable, honest guy and did do a lot of testing on my car. He wants to try putting in an aftermarket MAF to see if that fixes it and then gave me some other possible culprits. I know far, far, far less than he does about engines so my question is this: to everyone suggesting the coil packs, did you have the EXACT same issue as me or a similar issue? My car starts, idles and drives perfectly. I can drive it even moderately hard all the way to redline without issue. It is ONLY when I am at/near WOT under hard loads and above 4k RPM in any gear that my car jerks (like a fuel cut) then surges, jerks then surges. There are no other noises or other symptoms. Link to comment Share on other sites More sharing options...
FLlegacy Posted March 22, 2018 Share Posted March 22, 2018 Do you have a way to datalog? That would help narrow down the culprit. Basically any misfire is either an absence of air, fuel, spark, or compression. And WOT put the engine in open loop, so it ignores AFR readings and just dumps fuel in at a predetermined amount. The coil is the easiest to check by just moving to another cylinder, if the problem doesn't follow the coil then you can swap injectors to another cylinder and see what happens. Now mind you if you are doing all this swapping anyway a compression check is only a few more steps than a spark plug change. I would eliminate that possibility first since it will kill 2 birds with one tool. Ignition and compression. Link to comment Share on other sites More sharing options...
FLlegacy Posted March 22, 2018 Share Posted March 22, 2018 Have you tried just cleaning the MAF. Link to comment Share on other sites More sharing options...
ahkenaden Posted March 22, 2018 Share Posted March 22, 2018 My car starts, idles and drives perfectly. I can drive it even moderately hard all the way to redline without issue. It is ONLY when I am at/near WOT under hard loads and above 4k RPM in any gear that my car jerks (like a fuel cut) then surges, jerks then surges. There are no other noises or other symptoms. This is exactly how my issue started. Everything was smooth up to about 5500rpm as long as I was not WOT. If I did a WOT pull in any gear at any load, I got massive hesitation as soon as boost came on. If your code is P0304, it's very likely the coil pack. Not sure why that one always seems to go as it seems pretty common, but I would certainly start there as FLegacy said by having him move it to another cylinder and seeing if the problem stays/code follows cylinder. From my prior turbo car experience, bad MAF will do all kinds of other wacky things. Link to comment Share on other sites More sharing options...
LGTMKE Posted March 22, 2018 Author Share Posted March 22, 2018 This is exactly how my issue started. Everything was smooth up to about 5500rpm as long as I was not WOT. If I did a WOT pull in any gear at any load, I got massive hesitation as soon as boost came on. If your code is P0304, it's very likely the coil pack. Not sure why that one always seems to go as it seems pretty common, but I would certainly start there as FLegacy said by having him move it to another cylinder and seeing if the problem stays/code follows cylinder. From my prior turbo car experience, bad MAF will do all kinds of other wacky things. Ok this makes me feel more confident it could be the coil pack. What was a little odd to me was that the mechanic and I both thought the MAF would cause issues throughout the rpm range not just under wot conditions, but last night he basically said he can order a new one, try it out and if it doesn't fix it he can just return it since he has pull with the companies, saving me the cost of a new one if it doesn't work. Might be worth it in that case just to try. Assuming that doesn't work, and assuming he tries a coil pack to no avail, how much time does it take to switch around the injector with another to test that? Link to comment Share on other sites More sharing options...
FLlegacy Posted March 22, 2018 Share Posted March 22, 2018 I am kind of thinking the MAF wouldn't cause an issue to show up as misfire on just one cylinder it would be a multiple cylinder issue. Were there any pending codes? The ecm is pretty accurate when it sets a code, as it is looking for a specific set of data points and when they aren't met the CEL is set. Link to comment Share on other sites More sharing options...
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