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  1. #1

    Default Volvo Penta 305 to 350 running rough.

    Conversion from 305 270Hp to 350 330Hp.this is EFI and Multi-port and Running rough. I just bought a 05 Monterey 270hp GXI/SX from a guy who let the block freeze. I bought the boat 21', with the idea of dropping in a 350 adding a few pony's. I bought the block from an outfit in Kent, WA. They said there is no way the FI, multi port will know it's now sitting on a 350 and that they have performed this same conversion many many times.
    I just received a call from the mechanic informing me the motor sounds like it has a hot cam in. It's not running right, and hard starting.. It surges a bit then settles down but still rough running. This guy is meticulous and would have performed the work better than I. I'm not sure what to do at this point. I live in Boise Idaho, and I'm willing to drive it over to Kent but that seems ridiculous. In the off chance they have the wrong cam profile, should I even mess with flashing the Meffi/sp or I have heard pulse width issues, both over my head.. I have shelled out a few bucks for this thing and just needing advice on my next best move. Any and all help would be appreciated.. thanks...John

  2. #2
    Moderator Bondo's Avatar
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    Default Re: Volvo Penta 305 to 350 running rough.

    This guy is meticulous and would have performed the work better than I. I'm not sure what to do at this point.
    Ayuh,.... Welcome Aboard,...I'm a Carb guy, But,...
    I imagine all the usual diagnostic checks have been made,..??
    Fuel delivery from the tank,..??
    Stable Voltage,..??
    Compression,..??

    Good Luck...
    Any Grease is Better,..... Than No Grease at All.......

  3. #3

    Default Re: Volvo Penta 305 to 350 running rough.

    Yes, all that checks out. But there are so many differences of opinion. If the meffi 4cannot be flashed, then would it be wise to buy a 350 ECM?? Would that solve the issue?? They are expensive, and I'm not wanting to just throw rocks at the engine. If that is my best option, I'll do it.

  4. #4
    Moderator Bondo's Avatar
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    Default Re: Volvo Penta 305 to 350 running rough.

    Don is the man who's equiped to answer your questions,.....
    And know he's going to what to know the Full model #,+ Serial #s of the original donor motor,..
    The EFI's identity...
    Any Grease is Better,..... Than No Grease at All.......

  5. #5

    Default Re: Volvo Penta 305 to 350 running rough.

    Easy enuf, I will locate that info tomorrow and trudge forward.. thanks a lot I don't want to hurt this motor so I'm asking a lot of questions in hopes of an inexpensive fix... ciao

  6. #6

    Default Re: Volvo Penta 305 to 350 running rough.

    Hmmm. apparently changing the timing 10deg BTDC solve the prob.. but becuz of the Cali emissions, I'm wondering it it's a little lean. The Mefiburn.. has peaked my interest for tweaks.. Thanks for lending an ear and directing me forward with the info i would have needed.. Happy Boating all....

  7. #7

    Default Re: Volvo Penta 305 to 350 running rough.

    Ok, according to the engine builders, they had the mechanic put the timing @ 10deg BTDC and that helped.

    The numbers are hard to read but here goes.. Looking at the Mefi4 it looks like
    1860029
    5.0\AFM\04USOI
    Module 3868330
    2005 Monterey GXI/SX 214FS
    Volvo Penta

    Indications, changing the timing from TDC to 10BTDC helped quite a bit. It's still not right.
    Problems: I got it wet first time yesterday with the following results...
    started died, started died, started died, started stuggled to stay running and then died. Cranked it a bunch and after adding 1/2 throttle started and would only keep running if I feathered the throttle. Once it warmed up it ran smooth with a considerable amount of torque. WOT, trimmed and rpm's just below 5,000. No popping and a lot of torque with smooth reliable power.
    Started in driveway this am, same thing.. it seems to struggle at lower rpm's.. I pushed the throttle to about 1/8 and after picking up in rpm's stayed there and then suddenly ran up in rpm's running smoothly.

    I'm not sure what is the best route to go from here. Would it be wise to try and flash the Mefi4 with a 350 tune? The mechanic is at his limits with what to do, and I'm lost. I used to turn some wrenches some 30yrs ago and my how things have changed.
    Once the motor warms up (idles slow) it seems just fine. It stays running at idle and zero hesitation under full throttle.. I appreciate any help someone might be able to offer..

  8. #8

    Default Re: Volvo Penta 305 to 350 running rough.

    I just got off the phone with the engine builder who seems to think my trouble might be the MAT sensor?.. Worked great on the 305 but the 350 has issues. I'm looking to find it but still not sure that it will fix it...

  9. #9

    Default Re: Volvo Penta 305 to 350 running rough.

    News flash, the 350 doesn't have a MAT sensor sheeesh... I'm lost here

  10. #10
    Moderator Bondo's Avatar
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    Default Re: Volvo Penta 305 to 350 running rough.

    Once the motor warms up (idles slow) it seems just fine. It stays running at idle and zero hesitation under full throttle..
    Ayuh,.... Like I said,... I'm a Carb Guy,....
    But,....
    I think I'd be looking at the AIC,+ if there's a temp sensor problem....
    My thoughts there are,...
    The Automatic Idle Control should be bumping up the idle For you,...
    And,..
    If the 'puter was seeing a Warm motor, maybe it ain't telling the AIC to put more fuel to the motor,..??
    In other words,.. If it was a Carb,... The Choke is afu...

    Does your Mechanic have the diagnostic 'puter,..?? What's it saying,..??
    Any Grease is Better,..... Than No Grease at All.......

  11. #11

    Default Re: Volvo Penta 305 to 350 running rough.

    According to the mechanic, all codes and settings are reading right. There is some fluctuation in pulse width but he hypothesized the ECU is adjusting for the cam. I think we agree that something is not telling the ECU it's getting enough gas. So one of the sensors, either AIC or ECT.. this new stuff has be a little baffled. I'm used to carbs as well, and the older motors.. Or is the ECU preventing it because it's that much different than the 305?? I am willing to flash the MEFI4 with a 350 ,bin if that is the fix, but the programmer is expensive, and if it did not fix the prob... Lions tigers and bears!!!

    I appreciate your input, it helps me through this trouble shooting faze...I think I'm ok on the Columbia in a couple of weeks, but I would rest better with a correct fix...

  12. #12
    Moderator Bondo's Avatar
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    Default Re: Volvo Penta 305 to 350 running rough.

    I am willing to flash the MEFI4 with a 350 ,bin if that is the fix,
    Ayuh,... Google up an outfit outa Lake Havasu Az. called Arizona Speed & Marine....

    I hear they're up on the 'puter controls,....
    Any Grease is Better,..... Than No Grease at All.......

  13. #13

    Default Re: Volvo Penta 305 to 350 running rough.

    Well this has been a long time coming. I had my boat ck'd by two more people. One fairly knowledgeable while the second couldnt' even hook up to the diagnostic port. Even though the engine manufacturer (short block) told me my Mefi would not the difference between the 305 to 350, they were very wrong. I finally grew a sac. I could not save the info on the Mefi due to Volvo (password). I grew a sac, erased it, and installed a new .bin file on the Mefi. The first one did not work. I flashed it a second time, this time for the mefi4B. Voila, one click at cold start and my engine runs cold flawlessly. I may have lost some top end but I'm very pleased. I wanted to thank those of you who attempted to help. I bought my programmer two years ago but was afraid to erase the current flash on the Mefi. A Big Big thank you to Bob, with OBD2allinone down in cali. The flash took me all of less than 1 minute.

  14. #14
    Vice Admiral Tail_Gunner's Avatar
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    Default Re: Volvo Penta 305 to 350 running rough.

    Quote Originally Posted by rafting4fun View Post
    Well this has been a long time coming. I had my boat ck'd by two more people. One fairly knowledgeable while the second couldnt' even hook up to the diagnostic port. Even though the engine manufacturer (short block) told me my Mefi would not the difference between the 305 to 350, they were very wrong. I finally grew a sac. I could not save the info on the Mefi due to Volvo (password). I grew a sac, erased it, and installed a new .bin file on the Mefi. The first one did not work. I flashed it a second time, this time for the mefi4B. Voila, one click at cold start and my engine runs cold flawlessly. I may have lost some top end but I'm very pleased. I wanted to thank those of you who attempted to help. I bought my programmer two years ago but was afraid to erase the current flash on the Mefi. A Big Big thank you to Bob, with OBD2allinone down in cali. The flash took me all of less than 1 minute.


    You lost top end....Did you attempt your own tune or did you import someones file. you should have picked up big gains in HP and econ.....Hmmm did you buy the burn cd
    Stickly a opinion your milage may vary.

    Speed is how fast you hit the wall
    Torque is how far you move the wall"

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