2005 300X running rich

got a buddy with a stock 2005 300X. Out of the box this motor seems to run fine. Starts, idles, and runs fine. The issue is that it seems to be lacking power. The motor has had the DDT placed on it both in and out of the water. Compression tests, leak down tests have been done. I believe they have checked the tpi and also coils check out. Not sure if they checked injectors. After running for a day the prop has a lot of carbon built up on it. We also checked the thermos and throttle cable

I had the same boat/motor/setup as this guy. My boat was 7mph faster and turned a 26" prop to 6700+ This guy can't even put a 25" prop on the limiter... I think he turns a 24" trophy prop to 6100-6300rpm. Also in my boat if you whacked the throttle it would set you back in the seat. With his motor, when you smash the throttle the boat just slowly accelerates... What could it be?

This motor has always run like this and is now out of warranty. Could it be an ECU? I have heard that an ECU can check out on a DDT but still not function properly. This guy has seen 3 mechanics and has come up with nothing. Others Mechanics say that all the 300x motors have the same ECU but i have been told differently... Any help


Modified by Hydrilla at 3:35 PM 10/6/2009

Has Dominic looked at it yet???.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1outlaw &raquo;</TD></TR><TR><TD CLASS="quote">Has Dominic looked at it yet???.</TD></TR></TABLE>

At one point it was going to but has not made it there yet.

Dom is pretty good with them!! One way to ck the ecu is to try another and see if there is any difference.. Was wondereing if the front half has been off and all reeds checked??

Wouldn't hurt to have the injectors cleaned and checked also..

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Largemouthlou &raquo;</TD></TR><TR><TD CLASS="quote">Dom is pretty good with them!! One way to ck the ecu is to try another and see if there is any difference.. Was wondereing if the front half has been off and all reeds checked??

Wouldn't hurt to have the injectors cleaned and checked also..

</TD></TR></TABLE>

You got an ECU for him to try http://www.bassboatcentral.com/smileys/popcorn.gif http://www.bassboatcentral.com/smileys/Laugh.gif

There is a difference in the ecu's! The 2001 is different than the 2002-2005's. Not sure what the difference is between the 02's-05's. You should call Eric Simon and see what he thinks it is! He can also tell you the exact difference in the ecu programming from year to year.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hydrilla &raquo;</TD></TR><TR><TD CLASS="quote">

You got an ECU for him to try http://www.bassboatcentral.com/smileys/popcorn.gif http://www.bassboatcentral.com/smileys/Laugh.gif </TD></TR></TABLE>

No but you do!! Same yr and model, 3 bolts and 3 snaps http://www.bassboatcentral.com/smileys/smile.gif http://www.bassboatcentral.com/smileys/thumbsup2.gif

Yes there is a difference in the electronics from 01 to the rest of the yrs..

Has anyone tried a cylinder misfire test at WOT yet?

I'd recommend doing it.... and noting the RPM loss as each cylinder is "dropped".

If one is substantially "less".... that may help to narrow things down substantially. http://www.bassboatcentral.com/smileys/wink.gif

I would get the motor to Dominic!!! http://www.bassboatcentral.com/smileys/wink.gif