Misfire issues 05 Legacy GT

Discussion in 'Modifications And Maintenance' started by 00RSTI, Jan 7, 2017.

  1. 00RSTI
    Offline

    00RSTI Member

    Likes Received:
    1
    Trophy Points:
    13
    Hey, so I need to ask for help since I keep trying things and not making much progress I want to make my daily driver a stable running modded LGT. I've been having some drivability issues since I pulled my intake manifold to replace the gaskets and address some vacuum leak issues I was facing previously. Now, I can't seem to get it to stop having misfire codes and I'm trying not to keep shotgunning parts to fix it. Below are the details, I'm sure I'm leaving a lot out but this is a start.

    05 Legacy GT Auto, 202k miles
    Stage 2 - K&N drop in, cobb catless up-pipe, cobb catted downpipe, borla catback, perrin tmic
    Cobb Accessport, previously stage 2 tune, i've changed to the stage 1 for troubleshooting
    New Autolite iridium spark plugs gapped to .030

    As stated above, I had been chasing boost leak issues previously (I was seeing a max of 11-12psi on my AP) that led to me trying new intake gaskets. Recently I pulled the intake manifold, replaced all gaskets on the upper and lower, throttle body, ended up replacing multiple vacuum hoses and egr / pcv hoses due to being old and cracked. I did a pretty thorough inspection of the turbo inlet thinking there may be a crack but it looks fine so I reused. I had a vacuum leak on reassembly from the fuel injector seal (on the driver side rail) , I aligned those better and that seemed to help.

    Following the intake gasket replacement and once I tightened up the injector seal issue, I went from low boost to high boost and started getting misfire codes. The car never had misfire issues previously and ran well, now AP is showing peak boost hitting 17 and even 20 a couple of times and CEL pops, with misfire on cyl 2. I have a spare set of coil packs and have tried swapping out but that didn't help. I just got in a new set of iridium plugs to replace my 2 month old iridiums and made sure gap was correct and still get these misfires now. I am all for doing work and testing issues but I am just not sure where to look currently, I've been searching the LGT forums and tried a lot of ideas but would love to actually talk to someone who could help look at it.

    I've got cold beer, 2 heated garages and a lot of resources. Let me know if you have ideas or if you would come take a look with me.
     
  2. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    I would do a boost leak test as well as a compression test on cylinder 2 and 4.
     
  3. JasonoJordan
    Offline

    JasonoJordan Well-Known Member

    Likes Received:
    1,109
    Trophy Points:
    248
    I'd also do a leak down check as if you have not had your valve job done it could be a burnt valve. Pretty common on these cars especially at your mileage.
     
    jmyhre05 likes this.
  4. derp
    Offline

    derp Well-Known Member

    Likes Received:
    3,218
    Trophy Points:
    248
    @00RSTI jmyhre is Jesse from JM that I told you about today
     
  5. 00RSTI
    Offline

    00RSTI Member

    Likes Received:
    1
    Trophy Points:
    13
    Thanks Derp on the follow-up.

    As to the comments above, I had been putting off the compression test because I was stubborn and lazy I guess. I went ahead and pulled it apart tonight to finally do it and have an update. Cylinder #2 came back with pretty low compression - I tested a few times and 4-5 cycles to only 65 psi. Cylinder #4 seems more healthy at 130psi. Not sure how I managed to cross thread but #4 isn't going back in easy, guess I get to park the car for a few days until amazon sends a tap..... not how I wanted to be rewarded for digging in to this but I keep running into hiccups and new issues :( I wanted to check Cyl 1&3 but clearly that didn't get done once I got stuck on reassembly.

    I don't have the tools to do a leak down test but the kit isn't too expensive at harbor freight. I'll pick one up and have a look soon. I found a very informative thread on Legacygt.com outlining many of my same issues, valve job / adjustment seems like something I should be looking at too.
     
  6. derp
    Offline

    derp Well-Known Member

    Likes Received:
    3,218
    Trophy Points:
    248
    ouch.
     
  7. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    When you get it running again, start the car and pop open the oil cap. If white smoke comes out at all then you likely have a bad ringland. If not then it's not definitive and could still be ringland or burnt/worn valve. If you have a bad ringland another thing to check for is random excessive knock while driving. Or just a leak down test will tell you too.
     
    CornyTumbleweed likes this.
  8. 00RSTI
    Offline

    00RSTI Member

    Likes Received:
    1
    Trophy Points:
    13
    Sounds good, I should have the tap tomorrow thanks to amazon. It got stuck but I didn't force anything so I'm hoping it won't be too bad to clean up the threads.

    Another observation yesterday was I had climbing coolant temp at idle (holding normal at 195 due to cold air temp but idle I would run up 210 to a max of 230). I usually keep an eye on the gauges and haven't seen that before. I made sure to get it home and park but it didn't give me a warm fuzzy feeling.

    Usually I would associate that as a possible head gasket warning sign. Does that sound right or does that reinforce anything as to the ringland/piston.

    I do not recall hearing any knocking from the motor but I'll start listening.

    If I am looking at valve adjustments, does that mean the engine needs to be pulled? It doesn't sound like something that I would have enough clearance for while in the car but making sure. Sounds like my other projects will have to go on the back burner for a while. I've got a lift and air tools so.... when the time comes I'd be happy to trade favors later for some help on my first r&r.
     
  9. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    As far as knock it's not something you hear buy something your knock sensor will detect and your accessport can show you that data if you select it.

    To do the valve job you'll need to pull the engine.

    And if the temperature was rising that wouldn't likely be a sign of any of those engine problems, but more head gasket or other cooling system issue like low coolant, fans, thermostat, water pump, clogged system, ect...
     
  10. 00RSTI
    Offline

    00RSTI Member

    Likes Received:
    1
    Trophy Points:
    13
    Well, progress again. The plug went back in after I ran the tap so just a scare but the car is put back together. Summary of the compression by cylinder is as follows:

    2: 65psi
    4: 130psi

    1: 135psi
    3: 130psi

    I will pick up the leakdown test set tomorrow since it doesn't sound like anyone has one handy or is local and interested. I'll try to get it set up in the next couple of days.
     
  11. Krazylegz1485
    Offline

    Krazylegz1485 Well-Known Member

    Likes Received:
    1,135
    Trophy Points:
    173
    My fingers are crossed for ya that it isn't burnt valves...
     
  12. JasonoJordan
    Offline

    JasonoJordan Well-Known Member

    Likes Received:
    1,109
    Trophy Points:
    248
    Hope you used a metric assload of lube when you ran that tap in there to make sure any shavings didn't end up in the heads.
     
  13. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    Try the oil cap test, if smoke is coming out then you know Ringland for sure. But burnt valves would be better then ringland in this situation as it's cheaper to fix. Burnt/worn valves is very common for your mileage... actually would be surprised if it would be first valve job.
     
  14. jmyhre05
    Offline

    jmyhre05 Well-Known Member

    Likes Received:
    205
    Trophy Points:
    128
    If it's ringland you'll have the heads out already so you'll want to rebuild those anyways.
     
  15. 00RSTI
    Offline

    00RSTI Member

    Likes Received:
    1
    Trophy Points:
    13
    Okay, here is my weekend update. I should upload a pic of the tap but yes I greased it heavily, I am confident that most of the shavings came out with the tool.

    I started the car and looked for white smoke out of the oil cap and did not see white or any smoke coming up.
    I tried a leak down test and the results were not what I was expecting. Per the tool, I have minimal leakage which I wasn't sure I should believe right away. I guess maybe reading the gauges on the tool are not as helpful as just taking a reading of the pressure so... here is what I did.

    Test was done on cylinder 2, air compressor set to 95psi
    I screwed in the adapter and connected air, used low pressure to determine TDC and checked this at least 3/4 times, I also took my first reading then tried turning the crank around back to TDC to test again and got similar results.
    Again PSI into the air hose from the compressor was set to 95, I opened the valve on the leak down tester and got to a maximum reading of 70psi on the tool. there is a second gauge that determines leak down as high, medium, low etc... leak was below the low setting, I felt pressure against the crank pulley where my 1/2 ratchet was attached and it tried to drive the crank so, there is at least a decent seal.

    I turned the crank while the air supply was connected and could hear the difference between open and closed valves so, I feel relatively confident that the low leakage reading is correct or close to. I'm open to ideas at this point. I can keep running tests but I wasn't expecting a low compression reading to come back with no leakage. Thanks again for all of the input so far, I appreciate it.
     

Share This Page