IAC or TPS makes sence but we could not get any codes on the 271 w/496HO and the problem went away by it self

I assume you'r running 496's.. I had similar (but not identical) problems, Check you fuel pumps. oth HP and Lp. THere is a screen/filetr front of the lines. They canget clauged up, not enough or wrong fuel, sensors go nuts.

Yes.....IAC. You're in a soft alarm. 2 beeps per minute tells you it's a soft non-critial issue. At 4500 it goes into a soft guardian mode reducing your avaialable horsepower down to 90% and the alrm goes constant until you back it down to 1100 rpm where it goes back to the 2 beep deal. Rough idle is another indicator i.e. IDLE air control.

It's located looking aft, on the top rear of the motor near the throttle linkage mount. Kinda looks like a little thermostat. Two allen wrench type screws holds it on and a electrical connector. Simple, somewhat cheap and easy.

Tell your friend its 4 boats in a row installed a new one this morning and its is now running great.Thanks to everyone for your help Tim

Tim, did it set any codes? I would really like to know because we still don't know what was up with the 271

Never used the scan tool,The guy who owns the marina was not around so I just put on a new one.If yours does it again I would just change it

Thanks, Never has done it again but we will be look'n for it. Glad it was an easy fix for ya. By the way whatever happened with Micky Ds ?

If you have a Smartcraft engine, sometimes a bad IAC sounds the beeper, but a code does not always come up. I have also seen bad senders for the sea water pump pressure. The scan tool said it had 62 Lbs. at idle. No way a hose clamp could hold pressure like that or the hose not blowing up like a balloon.

Wish I had seen this thread a week ago. Had the exact same symptoms, and my marina shop chased the gremlin for a couple of hours before swapping the (good) starboard IAC to the (bad) portside. Viola! Problem solved, one new IAC for the portside and I'm back on the water.

Frustrating though, since I've only had about 5 days on the water this summer and was really looking forward to getting out that day. IAC problem hit the moment I splashed that day...

Its common for the 6.2s from what I have been told.I actually keep a spare with me.I got a lot of help from OSO and I also goggled the symptoms "engine alarm 6.2" went into a bunch of other boating forms.Which said IAC valve.