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View Full Version : 2005 X2 350 MCX idles high


bssteven
03-22-2014, 06:30 PM
So I have put the boat in twice this month trying to work out all the bugs before the season really gets going and I have a few issues. #1 I can't seem to find a good mechanic that is reasonably quick. #2 once warmed up the boat idles at 1350 rpm and prior to warming it idles erratically. A fuel injected engine should not do either of these things and I have no idea where to start. #3 after running about an hour we shut off the engine and it wouldn't start, the starter wouldn't even turn. It made one click like maybe it's stuck then after about 10 min of checking grounds and cussing it fired right up.
I'm thinking the starter may be sticking and in need of lube or replacement but the idle issue has me stumped. I read it could be the IAC but I have no idea where that is to inspect or clean it.
Please Help!!! Summer is coming fast...


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FourFourty
03-22-2014, 07:00 PM
#2 sounds like a temperature sensor to me. Coolant temp, or intake air temp. Try to get a wiff of the exhaust when it is warmed up, and see if it smells rich. A failed idle air control would be likely to make it idle high or low all of the time. It would be slightly different when hot or cold, but not usually a big change. Most of the time, I see this concern related to a failed coolant temp sensor. Sometimes intake air temp as well.


As for #3- it is very common for a starter, that is close to it's end, to not work when it is hot. Usually works when it cools down though. Next time it does it, tap it with a hammer, while somebody has the key turned to start position.

bssteven
03-24-2014, 06:53 PM
I have come to the conclusion that there is no idle air control sensor on my MCX. Does anyone know if it's part of the mono valve? Can someone point me in the right direction?


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sand2snow22
03-24-2014, 09:30 PM
Call Indmar tomorrow, they should be able to take you through some diagnostic steps. Starters are cheap and easy to replace.

mikeg205
03-24-2014, 09:41 PM
This could be a bad Throttle position sensor - throttle by wire to plug on motor. the sensor in the throttle handle goes bad possible to clean it - contact Bruce at action water sports - http://www.actionwater.com/

there's a thread here which I can't find at the moment

mikeg205
03-24-2014, 09:48 PM
Found it. http://www.mastercraft.com/teamtalk/showthread.php?t=56678&highlight=Mouser+Electronics

search mouser electronics

bssteven
03-25-2014, 10:10 AM
I just had a new throttle assy installed that was purchased from action water sports. Also has a new mono valve but I was having trouble with the idle until warm prior to the new parts.


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JimN
03-25-2014, 11:00 AM
I have come to the conclusion that there is no idle air control sensor on my MCX. Does anyone know if it's part of the mono valve? Can someone point me in the right direction?


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IAC isn't a sensor, it controls the amount of air allowed into the engine at idle. Think of it as a controlled vacuum leak at the base of the throttle body, behind the throttle plate (it wouldn't make any difference if it was outside of the throttle plate). If it's not in the correct position, the engine will idle high because the ECM doesn't "know" the position of the IAC's pintle (this is the part that opens and closes the opening that allows the air to go in). Look for a short cylindrical piece with a four-wire harness connected to it. Two of the wires will be blue, two will be green and one of each pair will have a black or white stripe. If you turn the key to the ON position, you should hear a slight buzzing sound from this part. If it does nothing, make sure the plug is fully seated. If this doesn't help, remove the plug and measure for voltage across each pair when turning the key to ON and repeat when turning it to OFF. If you see no voltage at any time (one pair opens it, the other pair closes it), check the harness.

IIRC, someone here posted the procedure for cleaning the IAC.

Before you do this, check the hose to the PCV- if this is cracked, you'll have high idle, but it won't affect cranking.

Make sure the ground cable's attachment point on the engine is clean. Also, inspect, clean and tighten the battery cables at the battery.

FourFourty
03-25-2014, 03:37 PM
Good call, Jim. Vacuum leak is another likely cause.

thatsmrmastercraft
03-25-2014, 03:48 PM
IAC isn't a sensor, it controls the amount of air allowed into the engine at idle. Think of it as a controlled vacuum leak at the base of the throttle body, behind the throttle plate (it wouldn't make any difference if it was outside of the throttle plate). If it's not in the correct position, the engine will idle high because the ECM doesn't "know" the position of the IAC's pintle (this is the part that opens and closes the opening that allows the air to go in). Look for a short cylindrical piece with a four-wire harness connected to it. Two of the wires will be blue, two will be green and one of each pair will have a black or white stripe. If you turn the key to the ON position, you should hear a slight buzzing sound from this part. If it does nothing, make sure the plug is fully seated. If this doesn't help, remove the plug and measure for voltage across each pair when turning the key to ON and repeat when turning it to OFF. If you see no voltage at any time (one pair opens it, the other pair closes it), check the harness.

IIRC, someone here posted the procedure for cleaning the IAC.

Before you do this, check the hose to the PCV- if this is cracked, you'll have high idle, but it won't affect cranking.

Make sure the ground cable's attachment point on the engine is clean. Also, inspect, clean and tighten the battery cables at the battery.

Good call, Jim. Vacuum leak is another likely cause.

Goes to show the importance of ensuring the basics are all good before going any further.