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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4724
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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What would cause slow idle miss and lack of power during acceleration?

Customer Question

what would cause slow idle miss and lack of power during acceleration? also can;t achieve maximum rpms. should be 5600 plus, but only get 4600.
Submitted: 2 years ago.
Category: Boat
Expert:  Jeff G. replied 2 years ago.
There are numerous things that can cause a problem like yours. My first inclination is you have a lean condition. On the Optimax engine this is usually taken care of by the ECM controlling the fuel and air. If the sensors are correct and they would set a code if they were faulty, then the area I would look at first is the injectors.This is a job best preformed by a qualified shop. The ECM monitors most of the parameters of the engine and sets the fuel parameters accordingly. One of the few things it can't account for is injectors min-behaving. By this I mean an injector is not opening all the way and is partially clogged.The injector opens when the ECM tells it to. The ECM also tells the injector how long to stay open. The injector having the fuel under high presure sprays a fine spray of fuel directly into the cylinder. If the injector were partially clogged, dirty, then the fuel may only dribble out which would cause most of it to go right out the exhaust. In addition the amount of fuel may be reduced. The ECM has no way to know the pattern or amount of duel introduced into the cylinder.The engine/ injector could be dirty from any number of reasons, long periods of idle, poor fuel or oil, etc. I would take the engine to a qualified shop, have them pull any codes that the ECM may have set, look for anything out of normal. They will use a scan tool or computer program to do this. Then I would have the injectors removed and cleaned. I'd bet this will take care of your problem and won't be an expensive repair. Injector cleaning is about $25 per injector plus the labor to remove and install them and the diagnostics. Not a big bill.Let me know if you need further help on this and the results.Thanks

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