Announcement

Collapse
No announcement yet.

m20 head rebuild misfire help!

Collapse
X
Collapse
 
  • Page of 2
  • Filter
  • Time
  • Show
Clear All
new posts
Previous 1 2 template Next
    #1

    m20 head rebuild misfire help!

    Hi, so ive recently rebuilt/refreshed my m20b25 head (headgasket was leaking a shit ton of oil before). I have got it running but it is misfiring on the 5th cylinder. I switched that spark plug out with a new one and it still misfired. Thinking it was a bad wire, i switched the wires with cyl 6 and same on the dizzy cap, but the misfire stayed on cylinder 5. Took the plug out and put the wires back normally and grounded the plug on the rocker cover, im getting spark. Also getting fuel because there is some only on that spark plug whenever i pull it out after starting it. I am also getting a lot of blue smoke (not right away on start up. I have put in all new hoses, teflon tape on all vacuum elbows, new hoses, belts ect. On the head i kept the old valve springs and rockers, but had a machine shop install new valve stem seals (they took out the springs and put them back in), resurface, valve seats ground, 3 angle valve job, hot tank, and valve guides. What is the next step i should take for figuring out what's going on? I have no idea what to do next. Please help I need my car back on the road asap. Thanks.
    Tags: None
    #2
    Swap that injector and see if the miss follows it. Evennthoughnits delivering some fuel it could be faulty
    Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

    https://www.r3vlimited.com/board/sho...86#post4944786
    Alice the Time Capsule
    http://www.r3vlimited.com/board/showthread.php?t=360504
    87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

    Comment

      #3
      Originally posted by jeffnhiscars View Post
      Swap that injector and see if the miss follows it. Evennthoughnits delivering some fuel it could be faulty
      Thanks for the quick reply. I rebuilt the injectors btw. What would be the quickest/easy way to swap them?

      Comment

        #4
        Just pull your questionable one and any other then switch locations. Pay attention to the o rings in case you kinked one. It could be that simple.
        Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

        https://www.r3vlimited.com/board/sho...86#post4944786
        Alice the Time Capsule
        http://www.r3vlimited.com/board/showthread.php?t=360504
        87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

        Comment

          #5
          Originally posted by jeffnhiscars View Post
          Just pull your questionable one and any other then switch locations. Pay attention to the o rings in case you kinked one. It could be that simple.
          okay...not sure if its worth doing it at this point though. Its smoking a shit ton of blue smoke and has nothing to do with the injectors i assume, even though its misfiring.

          Comment

            #6
            m20 head rebuild misfire help!

            I'm having a hard time trying to figure out why blue smoke would come out of the exhaust, got pics? When you drive it does the misfire persist or go away? I remember my eta used to misfire on idle and not when I got in the gas. Traced that back to a bad ground wire.


            Sent from my iPhone using Tapatalk
            sigpic

            Comment

              #7
              Blue smoke = burnt oil. Do a compression check on all cylinders, pay attention to #5.

              Comment

                #8
                Originally posted by dnguyen1963 View Post
                Blue smoke = burnt oil. Do a compression check on all cylinders, pay attention to #5.
                bump
                home from vacaction. I did a compression test, and got around 150psi all around super even. I pulled the injectors and a couple pintle caps stuck in the head. new o-ring, filters, and pintle caps and i haven't even driven the car yet. re assembled and swapped the injector to another cylinder. went to start it up and it started fine and wasn't missing...then the car started to spit a little bit of blue smoke after a minute or so, and then died. Like i said, the timing is perfect, head gasket was put on correctly and torqued properly, ignition is fine ect. No vacuum leaks. Went to start it a couple hours later and then it started misfiring right away like it was doing before. Im honestly stumped. Please help asap, i need my car back.

                Comment

                  #9
                  Was the number 5 plug oiled to the hilt? Is it only number 5 if so ? Maybe the stem seal is bad from bad install and fouling number 5.
                  89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                  new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

                  Comment

                    #10
                    Originally posted by digger View Post
                    Was the number 5 plug oiled to the hilt? Is it only number 5 if so ? Maybe the stem seal is bad from bad install and fouling number 5.
                    Thanks, sorry but what do you mean by hilt? Il check to see if the misfire stayed on the same cyl today.

                    Comment

                      #11
                      Maybe the misfire got worse after a couple hours because the oil seeped through the bad new seals to the plugs?

                      Comment

                        #12
                        How do the plugs look? You should be able to tell rich, lean, blow by, coolant, etc. from that. When you say the engine dies, does it stall out or does it get lumpy to the point that you shut it down? Do you know its a good head? You may want to do a leakdown test not just compression. You will get good compression numbers if there is a leak between cylinder and water jacket, especially if done at operating temps. This will tell you that the head gasket was not done properly or the head was warped/cracked... Did the machine shop skim the head?

                        Comment

                          #13
                          Originally posted by peterman View Post
                          How do the plugs look? You should be able to tell rich, lean, blow by, coolant, etc. from that. When you say the engine dies, does it stall out or does it get lumpy to the point that you shut it down? Do you know its a good head? You may want to do a leakdown test not just compression. You will get good compression numbers if there is a leak between cylinder and water jacket, especially if done at operating temps. This will tell you that the head gasket was not done properly or the head was warped/cracked... Did the machine shop skim the head?

                          Yeah, they did a leakdown test and skimmed the head. they put in the valve seals and all the valve work too. It died the first startup after swapping injectors. Went back out this morning. What i found is that cyl 2 and 6 are now fouled with fuel, and cyl 5 was crusty. swapped out cyl 5 and cleaned the rest off. Also did an oil change, the oil seemed to smell like fuel a little and was thin. Im using 20w50 castrol. When i moved the injector from cyl 5 (which wasnt firing before), to cyl 4, both of those cylinders are firing now, so the injector on that wasnt the problem before if that makes sense. Not sure why cyl 2 and 6 arnt firing, i pulled the wires on both and there was no change in idle. Idk what to do at this point. Oh, and I also did the compression test cold, so if there was anything that got in the combustion chambers that filled any bad rings/seals, giving me good numbers, thats not the case. fuck.

                          Comment

                            #14
                            I meant a leakdown test of the engine now - Not just the head. You may want to do another compression check. A new head with good compression can have a tendency to blow out the rings a little if its a high mileage engine. Crusty plug may make you want to check the valve stem seal...
                            Clean out your C101 connector as well.
                            Check the timing again. Make sure your tensioner is buttoned down good and tight.
                            Did you check your CPS?
                            Are your eccentrics too tight? is the valve staying open when it should be closed? Check your valve adjustment.

                            Comment

                              #15
                              Originally posted by peterman View Post
                              I meant a leakdown test of the engine now - Not just the head. You may want to do another compression check. A new head with good compression can have a tendency to blow out the rings a little if its a high mileage engine. Crusty plug may make you want to check the valve stem seal...
                              Clean out your C101 connector as well.
                              Check the timing again. Make sure your tensioner is buttoned down good and tight.
                              Did you check your CPS?
                              Are your eccentrics too tight? is the valve staying open when it should be closed? Check your valve adjustment.
                              Ok thank you. I have already cleaned out the c101 and c191 both in great shape, cps is good, and I had a friend who knows his shit do my valve adjustment for me and it's perfect. it's not a high mileage engine- only 140k. how can I check the timing with all that stuff in the way on the front? Sorry probably a dumb question but do I have to take all the covers off? What about inspecting the stem seals? thanks so much for your help dude

                              Comment

                              Previous 1 2 template Next
                              Working...
                              X