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Volvo 8.1 nightmare

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  • Volvo 8.1 nightmare

    My 2007 Chaparral 256ssi (8.1) has been a nightmare. Last summer i had to replace the engine due to what i believe was a lean fuel ignition causing a broken piston. I had the entire engine rebuilt and put it back in. I got it all together and running and put the boat in the water. I had it out for 20 minutes and seized up the upper out drive. Some how i lost nearly all of the oil. I know for a fact that i put the correct amount in because i had the container still.
    4K later, i have the boat all back together. I replaced the starter as well at this point because the old one had a loose connector on the solenoid and i just figured i would get it all over with at once. When i started the engine with the new out drive and starter, it turned once and then the starter just started to grind. I took the starter out and found that it had chewed up the flywheel. I ran the starter on a bench and found it was not engaging fully causing it to trash the gear on my flywheel. Now the engine has to come out again. I was able to replace just the ring gear on the flywheel. I finally got it all back together and got the boat in the water.
    At this point everything seemed ok with one exception. The boat seems to run very rough at 800 - 1200 rpms. Below or above that it seems fine. It almost seems as if it is misfiring. Once i get about 1200, it it fine. I also noticed that once in a great while, when i start the engine, it seems to jump around. Almost as if it is only running on 3 cylinders. If i shut it off and restart it, it is find until the next random time it does it. if it starts normally (99%) of the time, it is fine. That one in a hundred times, it dances until i shut it off which is always immediately. Then i restart it and its good to go.
    Here is what i am thinking. Since changed the ring gear on the flywheel, maybe i screwed up the balance? Im wondering if that could be the cause of the dancing and well as the rough run at 8-1200 rpm.

    Any thoughts?


  • #2
    You don't have a balance problem. Out of balance is not intermittent.

    How did the motor run before the flooding and piston destruction? Did you find the cause of the lean condition?
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    • #3
      it ran fine prior to the blown piston. this started before the flooding problem. I was also thinking an issue with the outdrive even though it is brand new. I had a ***** of a time getting the engine alignment right although i believe i did get it right. The alignment tool slid in and out with very little effort. All in all the boat runs well with that one issue. I just remember when i first bought the boat it was smooth at all rpms.

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      • #4
        As far as the balance goes, i would agree that it would not be an intermittent problem. But i also know that when you have a tire out of balance and it causes a shake. Sometimes you dont experience it and sometimes you do.

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        • #5
          With it being intermittent, look for electrical connection on Air control valve, crank position sensor, PCM and a loose ground
          94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
          95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
          07 Seadoo GTX
          Merc Adults Only VP Adults Only
          G-Dad always said "First Liar doesn't stand a chance"

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          • #6
            Well, although the dancing when i start it is intermittent, the roughness at 8-1200 rpms is spot on, every time. I will check all of the electrical connections again i just have it in my mind that is has something to do with the balance.

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            • #7
              it has nothing to do with balance. that is a mechanical impossibility. better chance of winning the lottery 10 times in a row, than that happening.

              it has to do with either lack of fuel (running lean) or lack or spark or you have wires crossed.

              you need to plug in Rinda and see what is going on.
              Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

              1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

              Past Boats
              1970 Wooster Hellion - Merc 9.8
              2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
              1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

              What’s behind you doesn’t matter.Enzo Ferrari

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              • #8
                although the dancing when i start it is intermittent, the roughness at 8-1200 rpms is spot on, every time.
                This could be idle air control, MAP, fuel pressure, vacuum leak. Scanner would provide some insight
                94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                07 Seadoo GTX
                Merc Adults Only VP Adults Only
                G-Dad always said "First Liar doesn't stand a chance"

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                • #9
                  Is your engine carb`d or EFI? G, GX or GX-I?
                  Summer Fling-II
                  2008 Chaparral Sunesta 264
                  Summer Fling
                  2003 Chaparral Sunesta 243

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                  • #10
                    EFI . 8.1Gi-H . Has no IAC. Still researching the others and buying a scanner.

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                    • #11
                      Has no IAC.
                      The IAC is term used by Merc
                      The Air Control Valve is term used by VP

                      All fuel injected motors have either a IAC or ACV. They are either part of the TB or the intake manifold. The issue we run into with VP is they delete items no long available many times. Since the Merc uses the same intake as VP it could very well use the same IAC/ACV. See item 38 which connects to the TB

                      https://www.mercruiserparts.com/bam/...31816/11414/70
                      94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                      95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                      07 Seadoo GTX
                      Merc Adults Only VP Adults Only
                      G-Dad always said "First Liar doesn't stand a chance"

                      Comment


                      • #12
                        Originally posted by AllDodge View Post

                        The IAC is term used by Merc
                        The Air Control Valve is term used by VP
                        IAC is a term used by both MerCruiser and Volvo when the engine has one.
                        The 8.1Gi-H doesn't have one. It has an electronic throttle body and uses the butterfly to control idle speed.
                        Not sure where your getting Air Control Valve from as Iv'e never seen Volvo use that term. Volvo will sometimes use the term sensor in their parts list when referring to the IAC, why I don't know.

                        jgerardi
                        Volvo had a service bulletin about vibration caused by a bad coupler and it only showed up at a certain RPM. So an out of balance issue can and will sometimes only show up at a specific RPM. But based on your symptoms I think it's only a remote possibility.
                        When your engine block was replaced, was a new crank position sensor installed?
                        I agree that a good scan tool may speed up the troubleshooting and maybe pay for itself. But be aware that the scan tool is only 1/2 of it. If the scan tool operator doesn't have enough knowledge it can be worthless.
                        Good Luck Muc

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                        • #13
                          IAC is a term used by both MerCruiser and Volvo when the engine has one.

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                          94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                          95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                          07 Seadoo GTX
                          Merc Adults Only VP Adults Only
                          G-Dad always said "First Liar doesn't stand a chance"

                          Comment


                          • #14
                            AllDodge Thank you for correcting me. I’ve never seen Volvo use that term before. What engine did you find that on? I’m pretty sure that if you look at the service manual for that engine, you will find that they call it an IAC. I have found that it’s best to take Volvo’s part descriptions carefully. As I posted earlier they will quite often call this component a sensor in the parts catalog. I find this very strange because a IAC is an actuator and provides no electrical feedback to the ECM. My guess is that some of these strange descriptions are the result of a Swedish to English translation.

                            But I do stand by my statement that the O.P.s engine doesn’t have a IAC, Air Control Valve or a Idle speed air valve. And yes I’m aware that if you look up the 8.1Gi-H engine in the parts catalog, Volvo will list a Valve, idle air control. But my guess is that they are referring to the butterfly, because that’s what controls idle speed on this engine.
                            Good Luck Muc

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                            • #15
                              Sign up today
                              I don't look at the VP manuals much (my very short comings), just try to assist and mess up not rechecking, glad your here.

                              Been looking at that term for a long time and find it on most (will not say all, sure I missed some) parts listing found at marine parts europe. That was on a 5.7 Gxi, Gi and others. Found also on some 4.3's. My bad issue as before I just keep finding the term so it started to stick.

                              Glad you pointed out the IAC, because I look at a few VP manuals at boatinfo and did find IAC, so I will try to stop using the other term
                              94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                              95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                              07 Seadoo GTX
                              Merc Adults Only VP Adults Only
                              G-Dad always said "First Liar doesn't stand a chance"

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