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  1. #1

    Default Throttle Problems with a 2015 5.7MPI engine

    I have been having some throttle problems with my 5.7 multipoint injection engine. The engine runs fine up to about 3300 and when throttle is increased beyond that range I get no immediate response from engine then suddenly the engine will race up to about 4000rpm. I can not stop the rapid increase even by reducing the throttle control. My boat wont plain at that rpm or get to cruising speed. The engine is only a year old and has run fine up to this point. I have hooked up a computer to engine to check all the trouble codes and found 2. The 2 codes were for the same malfunction, Electronic Throttle control pedal malfunction.

    My engine has the conversion from mechanical throttle control to electronic. My throttle cable connects to a electronic throttle control sensor which sends information to the throttle body to increase or decrease fuel. The manufacturer sent me a new potentiometer to correct codes but it did not correct problem.

    Manufacturer now believes it is a fuel issue and not a malfunction with engine. My mechanic doesnt think it is a fuel issue and thinks throttle body is malfunctioning.

    Help!

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,758

    Default Re: Throttle Problems with a 2015 5.7MPI engine

    If its still under warranty, why not have the local dealer diagnosis it???

    Having the code from the computer doesn't mean change a part - it just tells you what the computer has found that's not 'in bounds'.

    Never seen a full up e-throttle on a boat, but have on a truck....that had redundant sensors and a mismatch was that issue...

    did you view the TPS output with the scanner?

    Finally, check the fuel pressure in the rail if it isn't sufficient, the engine won't rev up under load...

  3. #3

    Default Re: Throttle Problems with a 2015 5.7MPI engine

    Unfortunately, there is not a local repair facility that provides dealer services. I forgot to mention that the high pressure fuel pump stopped working and manufacturer sent me replacement which I had installed a week ago. I ran engine and it had the same problem. The manufacturer asked that I run the engine bypassing the fuel tank and use a small fuel can. They wanted to eliminate the possibility it was a fuel issue. I had mechanic remove all the trouble codes from computer and tested boat last weekend. I ran it on the fuel can and switched it back to main tank to test results. The engine ran fine on both fuel supplies. Is it possible that once mechanic reset computer that it corrected whatever the problem was? Just glad it worked correctly but concerned as to what happened and how come it was difficult to diagnose.



    Quote Originally Posted by makomark View Post
    If its still under warranty, why not have the local dealer diagnosis it???

    Having the code from the computer doesn't mean change a part - it just tells you what the computer has found that's not 'in bounds'.

    Never seen a full up e-throttle on a boat, but have on a truck....that had redundant sensors and a mismatch was that issue...

    did you view the TPS output with the scanner?

    Finally, check the fuel pressure in the rail if it isn't sufficient, the engine won't rev up under load...

  4. #4
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,758

    Default Re: Throttle Problems with a 2015 5.7MPI engine

    I seriously doubt the code clear/reset resolved your issue....and bummer on not having a local dealer to cover the warranty....

    If is a new engine in an old hull, you may want to replace the anti-syphon valve as preventive maintenance.

  5. #5
    Join Date
    Dec 2011
    Location
    San Jose del Cabo, MX, Osprey, FL
    Posts
    306

    Default Re: Throttle Problems with a 2015 5.7MPI engine

    Tough there is not a qualified dealer near. This kind of problem with this kind of engine is very easily findable and fixable if your mechanic or you has a diagnostic manual and a scanner (this is a big step up from a code reader). I am not up on the current MEFI controller in your engine but based upon the sensors involved it must be very close to previous versions. Search under Pirate 4x4 on the web and read the article on MEFI controllers. This will give you the fundamentals on how it works. You can also download a manual there (300+ pages) for an earlier version of the controller that will likely meet you needs. Based upon a knowledge of the system you may be able to do some tests and figure out the problem. As an example when you increase the throttle, you really only open the throttle plate allowing more air into the manifold. Then the increased air pressure in the manifold (MAP) causes the computer to leave the injectors on for a longer time, and the combination makes the engine go faster. So you have a delay, and then an acceleration. Where in that cycle is the delay occurring? Which sensor might be slow in responding?

    But to really get to it you need the scanner (only sold by Rinda). Then you can read the actual outputs of the sensors and determine what is not responding correctly. And it gets even easier if you have a side by side known good engine to compare for data. But even if you are single engine, the scanner and manual can provide an answer.

    Or if if you do have two engines, there are only a half dozen sensors that are likely the issue. Swap them logically one by one and see if the problems moves.

    Good luck

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