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  • LT1 runs like crap...I'm stumped

    1995 Caprice wagon, iron-head LT1 350.

    The engine is bucking, sputtering, and hesitating. Plugs are OK, wires are new. Fuel pressure is fine, filter new. This started when the front of the motor came apart to fix a massive oil leak...it's worst at low RPM's under load (climbing hills in OD, mostly), doesn't do it much (if at all) when the engine is cold.

    Also, I recall seeing in Hot Rod (might've been Car Craft) that MSD had a drop-in Optispark replacement that cost less than the regular part-store thing...however, the only one listed on their site is the Pro-Billet one for about $550. (That's not what I want.) Err...help!
    John
    2007-2008-2009-2010-2011 Long Hauler
    Detroit-Muskegon 2012
    Couldn't make 2013

  • #2
    Temp Sensor

    The 94 did the same thing. you get the stuttering at about 35-45mph?

    The MSD unit number is MSD-83811, this is the OptiSpark Vented Style
    Last edited by Runner1972; April 30, 2011, 10:15 AM.
    "I live for myself and I answer to nobody."

    -Steve McQueen

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    • #3
      STICKING VALVES ? EGR STICKING ?

      leakdown test /compression test /fuel injector balance test

      Comment


      • #4
        Do a search here first. or try to look through the threads for similar issues. Don't join and have your first post be about your issue. These are a good bunch of guys, but that won't go over well.

        A forum community dedicated to Chevy Impala SS owners and enthusiasts. Come join the discussion about performance, modifications, troubleshooting, maintenance, and more!
        58 Plymouth Sport Suburban. 526 cubic inches of angry wedge! Pushbutton shifted 9 passenger killer!!"

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        • #5
          Could be coolant/water/oil in the cap, causing bad crossfire.

          Being right below the water pump, and attached at the crank has
          it's advantages, this is not one of them.
          Last edited by min301; May 1, 2011, 01:03 PM.

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          • #6
            Originally posted by Runner1972 View Post
            Temp Sensor

            The 94 did the same thing. you get the stuttering at about 35-45mph?

            The MSD unit number is MSD-83811, this is the OptiSpark Vented Style
            No, it's most noticeable at 60-75MPH, worst when pulling highway hills.

            The 83811 is the Pro Billet.
            John
            2007-2008-2009-2010-2011 Long Hauler
            Detroit-Muskegon 2012
            Couldn't make 2013

            Comment


            • #7
              Jegs used to list a couple of opti-sparks, I think in the 200-400 dollar range. Been a year since I looked.

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              • #8
                Replace the Opti-spark, it probably got f'd up when you resealed the front of the motor.

                Comment


                • #9
                  if the opti-spark has junk in it from the reseal, could you..
                  this all repends if the opti- has a vent,
                  take an a/c vacuum pump and suck all the junk out, I know it boil the water out of it, no idea what and oil would do, other than be sucked out..
                  no idea if the seals would handle it or just let more oil in under vacuum..
                  but if it's just water, it seam an easy way to dry it.

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                  • #10
                    Originally posted by Stich496 View Post
                    if the opti-spark has junk in it from the reseal, could you..
                    this all repends if the opti- has a vent,
                    take an a/c vacuum pump and suck all the junk out, I know it boil the water out of it, no idea what and oil would do, other than be sucked out..
                    no idea if the seals would handle it or just let more oil in under vacuum..
                    but if it's just water, it seam an easy way to dry it.
                    You know I live MSD, but if it's $550 to put a new MSD Optispark in it, you can do a whole Megasquirt for only a couple hundred more. If that actually. Rusty has the EMS Pro with a crank trigger I made myself using a Ford EDIS wheel, GM LS1 crank position sensor, and two 4 post coils from Pantera. You could skip the Pantera coils to save some money. Super easy to do and you have full tuning then. Stand alone EFI and timing control. It's awesome. Picked up as much as 60 hp and 80 lb ft under the curve over stock just by adding the stand alone and doing some tuning. It went from doing okay burnouts to blazing the tires through second gear. Way fun.
                    "A cross thread is better than a lock washer." Earl Lanning...My Grandpa

                    Comment


                    • #11
                      Originally posted by BangShiftChad View Post
                      You know I live MSD, but if it's $550 to put a new MSD Optispark in it, you can do a whole Megasquirt for only a couple hundred more. If that actually. Rusty has the EMS Pro with a crank trigger I made myself using a Ford EDIS wheel, GM LS1 crank position sensor, and two 4 post coils from Pantera. You could skip the Pantera coils to save some money. Super easy to do and you have full tuning then. Stand alone EFI and timing control. It's awesome. Picked up as much as 60 hp and 80 lb ft under the curve over stock just by adding the stand alone and doing some tuning. It went from doing okay burnouts to blazing the tires through second gear. Way fun.
                      I know either HRM or CC had a section recently about getting rid of the optispark as a high voltage distributor and going to a DIS style coil pack setup amoung other options.
                      Central TEXAS Sleeper
                      USAF Physicist

                      ROA# 9790

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                      • #12
                        Originally posted by TC View Post
                        Replace the Opti-spark, it probably got f'd up when you resealed the front of the motor.
                        I didn't do that...I lost my tools & anyplace I can wrench, I had someone do it. If that's the case...well, if that's the case, I'm thinking he owes me an Optispark!
                        John
                        2007-2008-2009-2010-2011 Long Hauler
                        Detroit-Muskegon 2012
                        Couldn't make 2013

                        Comment


                        • #13
                          saw a lot of optispark get replaced ...and it was something else
                          Last edited by SpiderGearsMan; May 5, 2011, 05:49 PM.

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                          • #14
                            Originally posted by SpiderGearsMan View Post
                            saw a lot of optispark get replaced ...and it was something else
                            With the OptiSpark it will throw either a DTC 16 or a 36 code.
                            Check the wiring leading to the optispark it could have damage to it from the seal change.
                            "I live for myself and I answer to nobody."

                            -Steve McQueen

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                            • #15
                              The CEL isn't on...no codes.
                              John
                              2007-2008-2009-2010-2011 Long Hauler
                              Detroit-Muskegon 2012
                              Couldn't make 2013

                              Comment

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