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6.2 mpi idle problem

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Skipper Rinaldi
New member
Username: skipperroo

Post Number: 1
Registered: 09-2008
Posted on Monday, December 28, 2009 - 05:58 pm:   Edit Post Delete Post View Post/Check IP

I have a pair of 2002 6.2mpi v drives. Starboard engine starts fine but when you put it in gear it won't stay running until it warms up . I have changed the IAC with no results. It runs fine cold at idle but as soon as you put it into gear it kills. It restarts immediately but does the same thing until it reaches 165 deg. The fuel filter is new, fuel is fresh and stabilized, the distributor cap is clean, throtle valve is clean, air cleaner is clean, and idle speed is good.
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Bert Goodrich
Advanced Member
Username: bertg

Post Number: 305
Registered: 10-2006


Posted on Thursday, December 31, 2009 - 12:59 pm:   Edit Post Delete Post View Post/Check IP

Intake manifold gasket may be faulty.
Bert
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Skipper Rinaldi
New member
Username: skipperroo

Post Number: 2
Registered: 09-2008
Posted on Thursday, December 31, 2009 - 02:20 pm:   Edit Post Delete Post View Post/Check IP

Thanks Bert,

I think I ruled this out because I sprayed the intake, other potential leak areas, and throttle body with liquid soap to see if it would make any difference. It did not affect the idle at all therefore I concluded that there were no leaks.

I also static checked all of the sensors with a digital volt meter and they all had the same readings from the port engine to the starboard engine indicating that the sensors are probably good. The port engine runs fine so I know all of the sensors are working properly. I have never heard of the spark plugs or coil causing this type of problem and the engine runs fine up to 5100rpm's. Do you have any other suggestions?
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Guy Gaspar
Senior Member
Username: guyjg

Post Number: 5527
Registered: 08-2006
Posted on Thursday, December 31, 2009 - 02:44 pm:   Edit Post Delete Post View Post/Check IP

Is the idle rough when cold? A minute amount of dirt on the throttle body wall and throttle plate can cause rough idling. Spray clean it w/Throttle Body cleaner and NOT CARB cleaner. Wipe clean w/paper towels. Also clean the IAC air passage.
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Skipper Rinaldi
New member
Username: skipperroo

Post Number: 3
Registered: 09-2008
Posted on Thursday, December 31, 2009 - 03:26 pm:   Edit Post Delete Post View Post/Check IP

Thanks Guy,

It idles fine just kills when cold and I put it in gear. The TB is clean. Can't type details from my blackberry but please see earlier posts where you can see everything I have checked so far. Hopefully you will come up with something I have overlooked
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Guy Gaspar
Senior Member
Username: guyjg

Post Number: 5528
Registered: 08-2006
Posted on Thursday, December 31, 2009 - 04:29 pm:   Edit Post Delete Post View Post/Check IP

Can you verify that the throttle plate is opening up properly?
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Skipper Rinaldi
Member
Username: skipperroo

Post Number: 4
Registered: 09-2008
Posted on Thursday, December 31, 2009 - 05:09 pm:   Edit Post Delete Post View Post/Check IP

Yes the throttle plate is working properly.
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joe alongi
Advanced Member
Username: srdancer90

Post Number: 142
Registered: 02-2008
Posted on Friday, January 01, 2010 - 09:23 am:   Edit Post Delete Post View Post/Check IP

TWhen you changed the IAC did you also change the little muffler in the trottle body? this may cause the engine to run thae way you discribed.
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Skipper Rinaldi
Member
Username: skipperroo

Post Number: 5
Registered: 09-2008
Posted on Friday, January 01, 2010 - 11:24 am:   Edit Post Delete Post View Post/Check IP

Hi Joe,

I did not change the muffler. Where exactly is it located in the TB?
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joe alongi
Advanced Member
Username: srdancer90

Post Number: 143
Registered: 02-2008
Posted on Friday, January 01, 2010 - 10:20 pm:   Edit Post Delete Post View Post/Check IP

When you remove the cover and look into the throttle body, you will see a fiberous whit looking material they cal this a muffler. I am not saying that this will cure your problem, however I have been told that it may cause the engine not to perform correctly. see the diagram http://www.perfprotech.com/store/assembly/THROTTLE-BODY,8094-70.aspx
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joe alongi
Advanced Member
Username: srdancer90

Post Number: 144
Registered: 02-2008
Posted on Friday, January 01, 2010 - 10:45 pm:   Edit Post Delete Post View Post/Check IP

I am going to ask some questions that you may already have the answers to, yet need to be looked into. Are you the original owner of the boat. If not do you know if the engines were ever over heated? Pull the codes off the computer to see. This issue sounds as if it is a head gasket, the computer will componsate for rpm at idle. Have you done a compression check on all the cylinders? I hate to sound as if the problem lies there,however if you noticed any difference in the position of the throttles under way, meaning one throttle is far more advanced foward to keep the same rpm range on both engines? there may be a problem in the head gasket.If not on all these questions, it will still not hurt to do a compression check. It will eliminate that part of the problem.
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Boat Tech
Member
Username: boat_tech

Post Number: 4
Registered: 01-2010
Posted on Sunday, January 03, 2010 - 07:48 am:   Edit Post Delete Post View Post/Check IP

I have seen a few post in the past where this same style engine has had some problems with either their valves, and/or their Intake manifold gasket have been faulty making the engine run really wired. You might want to do a Engine compression test just to be safe. And a engine leak down test should be done to.

Also you should check your fuel pressure at the fuel rail to see what it is really doing at all speeds, But mainly check to see if the fuel pressure is bouncing all over the place?

Also do you know the brand and part number to the spark plugs that are installed in the engine? There are some engine like yours that have been running really wired lately and it turns out to be the spark plugs. You should pull them and replace them just to be safe.

Have you had some one look at this engine with a scan tool hooked up?

And you may need to hook up a vacuum gauge to see what it is doing also.

Also what rpm does the engine idle at exactly?

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