DustinEgle Posted August 11, 2018 Share Posted August 11, 2018 Some backstory, this has happened twice before. But I will just refer to my current situation since its the same thing. I was driving home and everything was fine. Suddenly, I felt my car bog down (just cruising at 45). I looked at my MPG gauge and I was getting 10-12 mpg compared to my usual 23-28. I pulled over and that's when you really notice it. Sitting still idling the car is shaking dramatically, sounds horrible, and barely stays on. When i rev it up to 4g, and let it settle, it drops to below 0 and almost dies before sputtering back up barely. I decided to get home, and when taking off the car sounds horrible, also it's completely gutless. I decided to to a "pull" to see what would happen and it sputtered it's way up to 4g then suddenly it breaks loose and straight into boost and pulls like normal, really hard, but then it goes straight back to crap when you decel to normal. The other 2 times it happened it went away within 20 minutes and the car was perfectly fine, this time it's not going away and it's sticking around, so I'm at a loss. My AFR Readings after a little drive were 11-20. My first thought is maybe my AFR sensor? Any input is appreciated! Link to comment Share on other sites More sharing options...
Hardware BoB Posted August 11, 2018 Share Posted August 11, 2018 Sounds like a Vacuum leak - I'd be checking all my intake piping. Link to comment Share on other sites More sharing options...
ehsnils Posted August 11, 2018 Share Posted August 11, 2018 What you describe is the effect of transit from closed loop to open loop mode - in open loop mode the ECM is changing the way it calculates the fuel tune but in closed loop it's using all sensors from MAF, TPS, MAP, crank&cam sensors and both O2 sensors. In open loop it disregards some sensor data. The problem is most likely some sensor on its way out but it's hard to tell right away without experiencing the vehicle or having a good log to look at. It's useful to know if it's running rich or lean. But the mpg change indicates running rich. A rich condition isn't nice to the cat since it might get overheated. Realize that some sensors may be faulty even though the values from it are within spec. E.g. the MAP sensor may get stuck but still read within the stipulated range and that can give symptoms similar to what you describe. A code reader able to read pending codes is also a good tool to have. But just go around and check that all hoses are in place so it's not a simple problem. Also all wires and that nothing is loose that should be tight. And do check the turbo as well so it has minimal axle play if any. Link to comment Share on other sites More sharing options...
relative4 Posted August 11, 2018 Share Posted August 11, 2018 Almost certainly the upper O2 sensor. Use BtSsm, Torque, etc. to watch the voltages. Link to comment Share on other sites More sharing options...
JmP6889928 Posted August 11, 2018 Share Posted August 11, 2018 Ignition coil plug Link to comment Share on other sites More sharing options...
grovlet Posted August 12, 2018 Share Posted August 12, 2018 Ignition coil plug That was my 1st guess as well - the connectors are famous for falling apart:eek: Is there any codes:) Link to comment Share on other sites More sharing options...
DustinEgle Posted August 12, 2018 Author Share Posted August 12, 2018 No codes, couldn't find anything through the AP with my limited knowledge of using one lol Link to comment Share on other sites More sharing options...
DustinEgle Posted August 12, 2018 Author Share Posted August 12, 2018 Thanks everyone for the Input, I'm about to replace my upper 02 (afr) sensor and see if it corrects the problem. Couldn't find any vacuum lines disconnected. Ignition coil plug will be next if this doesn't fix it! Link to comment Share on other sites More sharing options...
JmP6889928 Posted August 12, 2018 Share Posted August 12, 2018 Reach in while it's idling rough and play with the coil plugs. I'll bet you'll find one you can wiggle a bit and the idle smooths out. Seen this at least 20 times. Link to comment Share on other sites More sharing options...
amptramp Posted August 12, 2018 Share Posted August 12, 2018 If it was a coil, you would probably get a flashing CEL for a misfire indication. But check the coils anyway - with an extremely rough idle, the ECU may not be able to calculate a normal period between plug firings so it would not light up the CEL. Let us know what you find - every bit of information makes it easier for the rest of us. Link to comment Share on other sites More sharing options...
ehsnils Posted August 12, 2018 Share Posted August 12, 2018 The change in behavior when going over a certain rpm is however what makes me suspect a sensor fault, which means that a logging may be helpful. It might be a coil or even a spark plug, but without enough data it's not obvious. Link to comment Share on other sites More sharing options...
DustinEgle Posted August 13, 2018 Author Share Posted August 13, 2018 (Through my phone I can't reply to the thread, I have to reply to a comment or else I can't say anything, so anything I say is for everyone.) Well guys I replaced the Front O2 AFR o2 sensor, no luck. Still extremely rough. Took it for a drive and it won't even pull, no boost at all. I thought I would check my MAD g/s and after a 5k "pull" it yielded 4.42/200.66. (My car is dynoed at 301whp 310tq with forged internals with 27k on the rebuild). I then pulled up my cylinder roughness for all 4. Cylinder 1, 2, and 4 are at 0. Cylinder 3 is throwing a party it looks like....0/100 And sitting at idle is quickly going from 1-100 And repeating. (It climes from 1-100 in about 16 seconds, and resets and does it again) this has me concerned, but being a novice to APs and mechanical situations like this, I can't say for sure what to expect. I also wiggled around my packs, but it made no difference in idle. Link to comment Share on other sites More sharing options...
DustinEgle Posted August 13, 2018 Author Share Posted August 13, 2018 Some spelling errors, (AFR, climbs) my bad. A few months ago this site changed and it's extremely hard to work with on my android. Everything is distorted) Link to comment Share on other sites More sharing options...
DustinEgle Posted August 13, 2018 Author Share Posted August 13, 2018 Also with my last 2 comments keep in mind. No codes are being thrown, and no CEL present. *shrugs* I'll wait for everyone's input, but I would assume spark plugs is the next step? Link to comment Share on other sites More sharing options...
JmP6889928 Posted August 13, 2018 Share Posted August 13, 2018 Blue T perhaps Link to comment Share on other sites More sharing options...
relative4 Posted August 13, 2018 Share Posted August 13, 2018 The next step is not to buy spark plugs, it is to identify the cause of the cyl 3 misfire. First, inspect the coil connector - wiggle it as JmP said, see if that affects the idle. If the pins are not contacting well, you can improve that by giving them a tiny bit of twist with needle-nose pliers. Also thoroughly inspect the wiring harness. If the wiring & connector look & feel OK and the twist doesn't help, swap the #3 coil with the #1 coil. See if the misfire follows. If so, replace the bad coil. If not, swap fuel injectors. If that doesn't find it, swap spark plugs. If you still have a #3 misfire after all that, it's time for compression & leakdown. Link to comment Share on other sites More sharing options...
hadvw Posted August 13, 2018 Share Posted August 13, 2018 I had exactly the same thing happen for a while when the weather was cold. Over time, got worse. Once car was warmed up, it was all good. After 2-3 winters like this and stalling in traffic a few times, I worked to track it down. Coil pack. Turns out I had a non-OEM pack somehow.. (looked almost identical, so it's possible one of the tuners accidentally did it or something). Replaced it with OEM, and no more problems. Link to comment Share on other sites More sharing options...
DustinEgle Posted August 13, 2018 Author Share Posted August 13, 2018 So good news update (hopefully)! I decided to swap my Cylinder 3 injector with the cylinder 1 injector to see if the problem followed to the #1 Cylinder. After removing my turbo coolant resivor and unbolting the fuel rail, i pulled out the injectors, cleaned off the gunk around the seals and swapped them. I put everything back together, turned on the car and it's running perfect! I did a stethoscope inspection with a screwdriver and all injectors are doing well (I wish i inspeced them this way before hand, but i forgot to). I am assuming the #3 injector wasn't seated properly? Or was loose? This was my first time dealing with injectors and the fuel rail system so it was a learning experience I enjoyed! I wish I would have known to pull the fuel pump fuse first and run the car out of gas because I got a nice gasoline surprise when I first unconnected the injector (rookie) haha. Now to hope the problem is solved! All cylinder roughness is now reading 0 and everything seems well. Link to comment Share on other sites More sharing options...
hadvw Posted August 14, 2018 Share Posted August 14, 2018 The change in behavior when going over a certain rpm is however what makes me suspect a sensor fault, which means that a logging may be helpful. It might be a coil or even a spark plug, but without enough data it's not obvious. I had the same issues with my car with a bad coil pack - stalling at idle, but fine above 4k rpm. I don't know exactly if the signal level goes up at higher rpm, and so it had an iffy connection until it reached a certain level or something, but rpm was definitely a factor in my bad coil pack. Those days when I got all greens so I didn't have to stop during the first 5 minutes and could keep the revs up above ~3k rpm, no issues. When I had to stop, if I kept the revs up (in Neutral), I could usually save it as well. OP - if it comes back, swap coil packs - much more likely than injectors in my experience.. Link to comment Share on other sites More sharing options...
Mork12 Posted September 10, 2018 Share Posted September 10, 2018 Hi I'm a newbie so please be patient...I am looking for answers to this very thing, as this happened to my '09 L SpecB and I cannot find anything wrong physically with the vacuum hoses, intake, or anything related to vacuum. I thought I had found the problem when I found a plastic nipple broken off on a solenoid valve connected by vacuum hose to the intake manifold. I replaced the solenoid valve, but that apparently wasn't all the problem, as I still have rough idle, bad shaking, no power, etc...What is the best way to 'find' vacuum leaks? Link to comment Share on other sites More sharing options...
relative4 Posted September 10, 2018 Share Posted September 10, 2018 The proper way to find a vacuum leak is a smoke test. Of course, your problem may not be a vacuum leak. An OBDLink dongle with the BtSsm app is a tremendous asset. Link to comment Share on other sites More sharing options...
DustinEgle Posted September 11, 2018 Author Share Posted September 11, 2018 I'm sorry, I forgot to update you guys on what the problem was because I have since fixed it. Failed injector. So here's the run down. I decided to pull up my Cylinder roughness values on my access port. Cylinders #1, #2, and #4 we're at 0, but cylinder #3 was cycling fast from 0-100 and repeating. After some contemplation, I decided to start by swapping my #3 injector with my #1 injector. After doing so I noticed the problem followed to the #1 cylinder, revealing my problem. Apparently, the resistance coil (I think that's what it was) failed in the injector according to the injector shop, and it was no longer functioning or fixable. This explains why the problem came and went a couple times before it completely failed, it was slowly dying haha. Apparently it's a rare issues with Denso injectors, but it can happen. I proceeded to buy 4 brand new Injectors so that way I didn't have 3 used and 1 new. The car is now doing just fine and has been for some time. Just got back from a 1200 mile vacation to the west coast from Idaho and 0 problems. I hope this might help someone else someday! Link to comment Share on other sites More sharing options...
moral hazard Posted September 13, 2018 Share Posted September 13, 2018 I've had this exact problem with my gen V. In my case I read a cylinder 4 misfire , turns out swapping that injector with a spare one I had worked. Before that I tried swapping coil packs with no luck. Had new injectors and the engine was recently rebuilt so I knew it couldn't be burned valves. So I guess injectors are well worth investigating when you get a misfire. Link to comment Share on other sites More sharing options...
Mork12 Posted September 13, 2018 Share Posted September 13, 2018 K. Just a heads up. I don't get on here as often as I wish I could so am late on replies as a rule... A couple things, I do have an Innova 3130c code reader that I am not very familiar with but am fumbling my way through. I can and have recorded live data recently but don't know how to decipher the data or the acronyms. I have 42 frames that I could take pics of and send to someone who knows how to decipher the values and knows the acronyms, and can explain to me how they derived what they think my cars' issue is. A few questions with the above subject vs BtSmm app and adapter. Thanks for the tip on that, relative4! I suspect that the BtSmm app will get more info than I supply from the code reader and will definitely be easier to send info for interpretation, but is there enough data from the code reader to determine what my problem may be? My funds are currently ridiculously low, so I'm in 'feed family mode only' at the moment. I would love to get the app and adapter now that I know a bit more on what it can do, but it will wait for now. On that, I do have 3 Subaru cars as stated on my profile. And I checked that the adapter and the app does work on all 3 cars. Do I have to get three different adapters and apps, or can I get one purchase of the adapter and the app, and then swap between the 3 cars seamlessly? Link to comment Share on other sites More sharing options...
relative4 Posted September 13, 2018 Share Posted September 13, 2018 Overlapping threadjacking, way too confusing. If you want to work this out, please start a new thread with your specific symptoms, mods, diagnosis to date. To save money, you can get a $15 VAG-COM cable from eBay and use it with the FreeSSM Windows app. Link to comment Share on other sites More sharing options...
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