Odd backfire. Timing/Wrong Sequence?

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  • A_Whelan
    Mod Crazy
    • Jul 2010
    • 691
    #1

    Odd backfire. Timing/Wrong Sequence?

    Hello,

    I finally manage to get fuel and spark by switching around two sensors, pretty simple solution that took a while to find. I've now been able to crank over the car and it's wanting to start but I'm getting a backfire through the throttle body.

    I've been told it's a possible timing problem? Or perhaps the plugs are firing in the wrong order. Is there any easy way to check these problems or start trouble shooting it?

    Also does the car need the MAF to idle? I might have the wrong intake boot elbow and it's not connected while I'm trying to start.

    Merry Christmas,
    Aaron
    r3vlimited Lanyard Group Buy!!!
    Tags: None
    • trackjunkie21
      No R3VLimiter
      • Jan 2010
      • 3962
      #2
      Check your coil connections, they are numbered, alo Matt-B had a similar no start problem, check that you have a aligning pin on your crank pulley, it should only bolt up one way.
      Your signature picture has been removed since it contained the Photobucket "upgrade your account" image.

      Originally posted by Wh33lhop
      VANOS: sometimes you just need to go full retard.

        Comment

        • TimKninja
          R3VLimited
          • Mar 2009
          • 2131
          #3
          Back firing through intake is a huge vacuum leak. Or you may have the vent line for the fuel tank hooked up wrong.
          1985 325e M50TU(Sold)
          1991 318is Slicktop (Sold)
          1990 325is Brilliantrot S50/5 Lug Swapped.
          1992 525i Manual shitbox Winter Beater

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            • Exodus_2pt0
              R3V Elite
              • Dec 2011
              • 5943
              #4
              Originally posted by trackjunkie21
              Check your coil connections, they are numbered, alo Matt-B had a similar no start problem, check that you have a aligning pin on your crank pulley, it should only bolt up one way.
              What he said.

              I don't have much experience with this platform (yet.), but what you're describing is pretty universal. Sounds like your ignition timing is wayyyyy off. Possibly due to wires in the wrong place or the ECU needs to get a clue as to where the engine is at in its rotation (sensor issue)
              No E30 Club
              Originally posted by MrBurgundy
              Anyways, mustangs are gay and mini vans are faster than your car, you just have to deal with that.

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                • Exodus_2pt0
                  R3V Elite
                  • Dec 2011
                  • 5943
                  #5
                  Originally posted by A_Whelan
                  Also does the car need the MAF to idle?
                  Generally speaking, if the MAF is unplugged before you start, then the car will run fine on a pre-determined fail safe fuel map.

                  I have picked up cars from people before that weren't running, and got it started by unplugging the MAF.
                  No E30 Club
                  Originally posted by MrBurgundy
                  Anyways, mustangs are gay and mini vans are faster than your car, you just have to deal with that.

                    Comment

                    • A_Whelan
                      Mod Crazy
                      • Jul 2010
                      • 691
                      #6
                      Really appreciate the posts guys. I'll start looking at these things.

                      In terms of a vacuum leak that might be a problem. On the back of the throttle body there is a hole and I'm not sure what hose goes there and I can't see it on realoem in either the m20 or m50 engines.

                      My build thread is here and I've posted a few things about the problem, most is listed here.

                      http://www.r3vlimited.com/board/showthread.php?t=207322
                      r3vlimited Lanyard Group Buy!!!

                        Comment

                        • polkadot_boxerman
                          Advanced Member
                          • Sep 2007
                          • 102
                          #7
                          You have two coolant lines that run through the throttle body. The other line should be coming from the charcoal cannister if I remember correctly.

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