View Full Version : Strange engine behavior
05-26-2013, 09:04 AM
Boat is a 2007 PS197 TT w/MCX and MEFI5. Engine fired up perfectly yesterday at the ramp. Idled around to bring the engine up to water temp, and then applied throttle to head for our spot. Took it normally up to about 3,500 RPM. After maybe 15-20 seconds, got a Check Engine warning and then engine dropped RPMs but kept operating. Checked gauges--all normal. Checked engine--running and sounding fine. No leaking hoses, belt great, etc. Throttled back up and engine spun fine but would not go above 2850 RPMs, regardless of throttle position. This truly seemed to be as though the top end was being governed/limited, vs. any issue with fuel delivery or ignition, since there was no misfiring, etc.
Ran about 10 mins that way and decided to stop. Let the boat sit for an hour or so. Restarted and it operated as normal for the rest of the day, running up to 4600 at WOT, although we are getiing a check engine tone every now and then. Looking for any experience or thoughts on what I could check, or if this is something that a dealer needs to service.
05-26-2013, 09:31 AM
Fuel pump getting weak?
05-26-2013, 09:55 AM
What is the condition of your battery and/or battery and ground connections. 2007 Models had a low voltage alarm. If I remember correctly, if the voltage drops below 10.5V (usually happens during the crank/start cycle) it will set an alarm and put the engine into power reduction. The alarm should go away after after several start/warm up cycles with out a repeat of a low voltage event.
05-26-2013, 10:12 AM
I have had this on my 08 x2 with mcx. Rpm was lower however, basically went into limp mode. Yours does sound related to fuel, I also agree with the battery check. Don't just test them for 12. Volts, get a draw test done on them, most battery places will do it it for free. Do you have the sensors on the elbows of your exhaust manifolds where it connects to the large rubber hose?
05-26-2013, 04:48 PM
Thanks for the ideas guys--I will look into all of them. I've experienced limp mode due to a bad t'stat, and this was definitely not that. The rev limit was very consistent at 2850, meaning it didn't surge or sputter--just would not exceed that point. This makes me suspect it wasn't fuel related as i think a delivery problem would result in more erratic revs.
The low volt sounds more plausible although my connections are all pristine as I did the dual batt install w/Borg Warner auto isolation relay this winter. The house batt is a new Optima Bluetop and lives on a charger/maintainer while garaged. Could be the starting batt is aging as I don't know its lifecycle--came from PO. Sems that's the first and easiest thing to check.
These random and unrepeatable issues are the toughest and in my experience are usually rotted in the electrical system. Time to buy a second oar!