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  1. #1

    Runs good - Rough Idle

    I have an '03 MSX. It still runs great except after it warms up, it idles real rough and dies frequently. This makes putting it back on the trailer rather a pain. My first thought is the thermostat pop off valve needs to be cleaned/replaced. Anyone have any thoughts.
    Last edited by EECOM; 07-02-2009 at 10:36 PM. Reason: spelling error


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome

    Click below for the service manual, and other useful info.

    You can clean and check the thermostat fairly easily.

    There are some basic checks you can do to see what is going wrong.
    TPS, injector voltage, fuel pressure...

    Have a look at this thread for starters

  3. #3
    ph2ocraft's Avatar
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    Install a fuel pressure gauge and see if it drops when your problem occurs.
    If you have never replaced the TPS, replace it as it will fail. If it doesn't correct the issue at least you have a spare and you can use it for testing other issues that may arise.

  4. #4

    Still Working on Rough Idle

    Looking at the service manual, for "DI" models (what ever that is) it states:

    "If the idle speed, while watercraft is in the water, is outside the above specifications, disconnect the TPS. A dramatic change in idle speed when the TPS is disconnected requires replacement of the TPS".

    I tried this in the garage. I disconnect the TPS, started the engine and the idle began to rev up real high before I shut it down. Looks like I'm going to buy another TPS and give that a try like "ph2ocraft" suggested. Thanks for your insight.

    BTW: I tried to check the thermostat & pop-off but I could not budge the 2 bolts. I'm a little concerned about putting a "cheater" to it.

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by EECOM View Post
    Looking at the service manual, for "DI" models (what ever that is) it states:

    "If the idle speed, while watercraft is in the water, is outside the above specifications, disconnect the TPS. A dramatic change in idle speed when the TPS is disconnected requires replacement of the TPS".

    I tried this in the garage. I disconnect the TPS, started the engine and the idle began to rev up real high before I shut it down. Looks like I'm going to buy another TPS and give that a try like "ph2ocraft" suggested. Thanks for your insight.

    BTW: I tried to check the thermostat & pop-off but I could not budge the 2 bolts. I'm a little concerned about putting a "cheater" to it.
    DI means Direct Injection, which is a generic name for the Ficht RAM fuel injection system.

    If the thermostat bolts are really stuck, apply some anti-corrosion (anti-rust) liquid to the bolts. The bolt holes may go right through the thermostat housing, so you may be able to squirt some up from below, and around where the two parts seal together, and around the bolt heads. Then let it sit for a while, with the occasional light hammer tap and additional fluid. A day or two of that should help it loosen up. Those bolts are stainless steel, so they won't take a lot of abuse without breaking.

    A replacement thermostat housing isn't very expensive (used), if it comes to that.

    You sure you unplugged the TPS?
    It is a three pin (three wire) connection.

    The engine should not rev up without the TPS.
    Make surre there is zero dirt, moisture or corrosion in those TPS connectors.

  6. #6
    I'll keep plugging away at the thermostat housing. You are right that the bolts do go through. I haven't looked with a mirror, but I bet that is where it is corroded.

    I am pretty sure I was unplugging the TPS. It has a 3 wire harness that goes to the sensor on the side of the throttle body as indicated on the maintenance diagram. I was trying this on a cold engine in the garage when it rev'd up while unplugged. I may try it again this week in the water after warm up to see what happens
    thx.

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