EX343 running rough at surf speed

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  • TylerDWilson
    • Apr 2017
    • 12

    • St Louis

    • SAN 230 Team Supra 22SSV-sold Mastercraft XStar-sold Sea Pro 260-sold

    EX343 running rough at surf speed

    So I have been experiencing an extremely puzzling issue from most of last season carrying over into this season.
    I have a 2009 SAN 230 with the EX343 with about 120hrs. At surf speed/RPM, fully loaded or not, the thing runs like a real turd. I mean the engine just acts like it hates running in that range, about 2900-3100 RPM.
    I typically run 4000lbs ballast. At wakeboard speeds the boat runs great, fully loaded, pulling a rider up, doesnt miss a beat. BUT, when going to surf, setting the ZO to 11, its like the boat doesnt even want to go there when you drop the throttle. It gets right up to about 8mph fine and then struggles to go from 8 to 11, and once at 11 it just runs really rough. It spits, spudders, and misses. Now, if I were to be surfing (with the rough running) and then turn off the ZO and pick the speed up to wakeboard speed, the boat will immediately power up and run great all the way through to 23mph and then run perfectly at speed. ITS WEIRD

    I have done everything to re-mediate the problem that I know everyone here will mention first off as the likely cause:

    Replaced all the plugs; double checked all the gaps prior to install
    Replaced the Cap and rotor - checked all connections for corrosion, there is not any.
    The prop is fine, I had it balanced just in case.
    I performed an engine alignment - got the shaft coupler within .0015" alignment (spec is .003)
    The dealership adjusted the Cam Retard (as that was a common issue for that generation boat and motor)
    Cleaned up both knock sensors, no corrosion and both have good connections. Voltage tested the wires and connectors.
    No check engine light issues.
    I replaced all of these things through the course of last summer. No resolution.
    Replaced both fuel filters this winter hoping it was a fuel issue. Nope, the boat behaved the same exact way this past weekend as it did last year.
    I have not replaced the plug wires but I really do not believe thats the issue.

    Any help is appreciated!


  • ScooterMcgavin
    1,000 Post Club Member
    • Jul 2011
    • 1478

    • Florida

    • 2014 SAN 210 TE

    #2
    I've got a question... It goes up to 8 fine then struggles from 8-11 mph with the ZO. Does it react the same way from 8-11 when doing the throttle maunually or is it just when you have ZO engaged ?
    2009 Super Air Nautique 210 TE
    2006 Super Air Nautique 210 TE
    1989 Sport Nautique

    Comment

    • TylerDWilson
      • Apr 2017
      • 12

      • St Louis

      • SAN 230 Team Supra 22SSV-sold Mastercraft XStar-sold Sea Pro 260-sold

      #3
      Good question, I thought that may be the problem as well. I ran the the ZO in rpm mode to see if it reacted the same. It did. I have tested it multiple times without the ZO driving manually, it reacts the same way.

      Comment

      • beamons
        Senior Member of PLANETNAUTIQUE
        • Jun 2017
        • 376

        • Utah

        • 2005 Ski Nautique Limited Looking for a 230 or g23 prev. 1998 Ski Nautique, 2004 Nautique SV211

        #4
        It is possible that something is in the fuel tank? It almost sounds like when the boat is at that particular plane something affects it.

        Comment

        • TylerDWilson
          • Apr 2017
          • 12

          • St Louis

          • SAN 230 Team Supra 22SSV-sold Mastercraft XStar-sold Sea Pro 260-sold

          #5
          I pulled both the inlet lines on the tank and the discharge line (with tank empty towards the end of last season) nothing appears to wrong within the tank

          Comment

          • James
            • May 2007
            • 151

            • Indian Wells, CA


            #6
            Have you checked the throttle position sensor?

            Comment

            • charlesml3
              1,000 Post Club Member
              • Jan 2008
              • 2453

              • Lake Gaston, NC

              • 2022 G23

              #7
              Originally posted by James View Post
              Have you checked the throttle position sensor?
              That's exactly what I was thinking. This is exactly how a failing TPS will behave. In almost all positions, it works fine. But in the one "dead spot" it goes haywire and reports all kinds of bad info to the ECM.

              Comment

              • TylerDWilson
                • Apr 2017
                • 12

                • St Louis

                • SAN 230 Team Supra 22SSV-sold Mastercraft XStar-sold Sea Pro 260-sold

                #8
                So I agree that a failing TPS would cause very similar issues to this, and I am definitely going to check it out! But, in this rpm range would it becausing the engine to miss?
                I ask because I do not know

                Comment

                • James
                  • May 2007
                  • 151

                  • Indian Wells, CA


                  #9
                  Mine started out going bad in one RPM range like yours and within 2 days went out completely. It is a less than 10 min, simple job to put in a new one. I friend of mine’s went bad in the 2100 RPM range and lasted for a season. (He was too busy to change the TPS).

                  Comment

                  • charlesml3
                    1,000 Post Club Member
                    • Jan 2008
                    • 2453

                    • Lake Gaston, NC

                    • 2022 G23

                    #10
                    Originally posted by TylerDWilson View Post
                    So I agree that a failing TPS would cause very similar issues to this, and I am definitely going to check it out! But, in this rpm range would it becausing the engine to miss?
                    I ask because I do not know
                    A failing TPS will cause all kinds of weird behavior. I had one going bad in my SUV and it took me a YEAR to finally narrow it down. Multiple tuneups, plug wires, coil, etc. All would make it run better for a while, but then it would come back. When it hit "the bad spot" sometimes it would lose almost all power. Like someone was holding the brake. Or it would nearly shut the engine off (I'd get a blinking ignition light) but then it would come right back. Other times it would sorta "buck." Felt like it was running on 5 cylinders for a few seconds but then come right back to normal. It might go a month without acting up, but then act up 3 times in one day. Very weird.

                    Multiple mechanics. Nobody could find it. Finally, I was griping about it at a Pep Boys store. Went through the entire story and some guy standing behind me said "that's a bad Throttle Position Sensor." He knew. $54 later it was fixed.

                    Given everything else you've done, this sure sounds likely. I hope this fixes it.

                    -Charles

                    Comment

                    • TylerDWilson
                      • Apr 2017
                      • 12

                      • St Louis

                      • SAN 230 Team Supra 22SSV-sold Mastercraft XStar-sold Sea Pro 260-sold

                      #11
                      Good info guys, this is very helpful. I will go ahead and replace it and see if that fixes the problem.
                      One last thing though. I was doing a little research about failing TPS' and most of the information I found stated that the failing TPS would trigger the check engine light, was this the case for you guys when yours went?
                      I am not throwing any codes.

                      Comment

                      • charlesml3
                        1,000 Post Club Member
                        • Jan 2008
                        • 2453

                        • Lake Gaston, NC

                        • 2022 G23

                        #12
                        Mine never did. I asked and the mechanic said it had to go into a failed state for several minutes before it would register a code. At best, I could only get it to fail for a few seconds. I saw the CEL come on, but it would never stay on long enough.

                        -Charles

                        Comment

                        • James
                          • May 2007
                          • 151

                          • Indian Wells, CA


                          #13
                          My CEL did not come nor did it on my friends boat

                          Comment

                          • James
                            • May 2007
                            • 151

                            • Indian Wells, CA


                            #14
                            FYI... my boat is a 2006 216 Excal 330. My friends is a 2007 236 with a ZR6.

                            Comment

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