View Full Version : LY6 400, after start up rev-up

09-20-2013, 06:26 PM
I have 2008 LY6 400 start up question. Engine starts readily then slightly revs and then settles back, revs then settles back, for about 12-18 seconds until she finally settles into a nice normal idle. This happens only on start up, all other running modes are fine. Anyone have any suggestions? Thank you.

09-20-2013, 06:36 PM
Mine does the same thing and I was told this is normal.

09-20-2013, 06:52 PM
Own entirely too many electronic fuel system engines and not one of them does what this one does. Imagine that engine in a chevy truck starting up and surging as ours seem to be. Online posts on other engine related forums suggest many culprits but what seems a common denominator is the "idle air control valve". This is not normal and can/will get corrected.

09-22-2013, 12:10 AM
Hey Ironhorse, I must apologize. I was informed today in no uncertain terms that these hotrod LY6 motors do indeed "lope" the RPMs a bit before they settle into a steady idle. Has to do with variable camshaft timing and oil pressure. Mastercraft guy said it's his favorite motor. '09 motors apparently are better about the RPMs but have catalytic converter and quieter mufflers. So again, apologies.

09-22-2013, 03:15 PM
Mine does this its an 08, essentially mine does it twice on start revs up, settles down revs up, then levels off.

I was not concerned as I have has this with other motor, not in a boat, and usually as long as it does not continue should not be an issue, but only my first LY6 motor.

09-24-2013, 12:24 AM
Mine only does it on cooler mornings and my dealer said it was totally normal. It sounds like I have high lift race cam in it. The dealer service manager said it was the ECM adjusting to the cool air and adding too much fuel then too much air. It idles out in about 15 seconds.......sure gets the looks from other boaters at the ramp. :)

09-24-2013, 08:09 AM
NP Woolsack!