5.0 MPI Low WOT, Dogging Hole Shot

[SRTroop]

2006 Sea Ray 205 Sport, 5.0 MPI, Alpha 1, 14x21P stock Vengeance prop, 180 hours.

Hi everyone. For the last summer and now this one,my boat will only produce 4100 WOT rpms and has a lousy hole shot. Performance is very consistent. Prop is in ok shape, hull clean. Had a dealer tune up this spring (plugs, distributer, wires, filters) and performance is the same. Cannot pull out a skier on one ski as easily with long hole shot. Engine does have a light ticking noise at idle but mechanic said nothing about it (could be belt).

Today I removed the Little iac filter inside the throttle body edge and it was just nasty. Ran a hole shot without it and the engine wound up to 4600 rpms and just purred with a ton of additional horsepower (made me remember what was missing) for about 200 yards before dogging again. A storm was coming so I didn’t get to try more, but this really got my attention.

Anyone have any simple ideas I can check before taking back in $$$ that are related to this filter? I’ve considered getting a more aggressive prop to see if I can simply increase my performance but want to do it right.

 

[QBhoy]

An immediate suspect would be the well known dizzy cap problem these have. I have the same engine and have been through 3 caps since 2015 and even one that failed before even fitting it. They show all sorts of issues from not even starting to random poor running and power loss.
What is your drive ratio ? If it’s the higher 1.47 I have a 21” might be pushing it on your boat maybe ? Maybe it’s the lower ratio. Hate to moan but that prop you have is a waste of time. It’s just a fancy looking standard shiny version of the normal ally prop. Has no real performance orientated properties at all.
Other problems with these engines are TPS, sw pressure switch, shift interruption switch but above all else the diz cap.

 

[SRTroop]

Thank you! I will try it. I’m having a hard time narrowing down the dizzy cap part...any different name or part number?

I know you are correct about the prop. I’m looking at going with a High 5 shortly but want to get my power issue under control first.

 

[SRTroop]

I thought the dizzy cap was part of the IAC or something and just realized you are probably referring to the distributor cap. I did just replace that with identical results on the rpm upper limit....

 

[achris]

Replace the IAC with one from a local car parts shop. Look for one for a Windstar... Should be about $50...

Chris.