2011 optimax 175 hp Speeds up in idle by itself

[stan73]

Mine has the Troll function but not ski mode that I know of. Yes it is a smart gauge.
It's frustrating as it does not do it all the time...and catches you off guard..only once have I noticed rev up in neutral coming from forward then slowing down by itself without having to turn the key off and on. not sure if that gives any more info on my problem

thanks for your advice

[Motv18]

I would go with the bleed down test on the fuel rail then check tps shift sensor.

I does a thing when shifting (some cut 3 cylinders) and then goes into in gear idle. If it jumps enough it will rev if not in gear.

Crank sensor blips can also create random idle, but it tends to affect high rpm more.

[stan73]

When you say "jumps enough" are you talking about the TPS sensor?
I think I am going to have to replace and test parts in real life life as it does not do this on a consistent basis

[Motv18]

It’s justa term here. Umm... think of it like jumping out of gear. Sensor says it is in fwd rev but it’s not. PCM adds fuel to keep it running, but not turning the prop it can rev a good bit. Takes a second for the system to catch up and calm the motor down.

Guessing on on the internet leaves many options open

heck you could have had a stuck throttle plate if the links a bit loose. Only the lever is connected the plate can bounce.

[stan73]

Thanks all of you, I have some very good ideas to follow through on this coming spring

thanks again
Stan

[jeffg]

run without smart craft hooked up,malfuntion from guages. tps second.leaking injector. i have had mant tps do this.pretention is important on throttle cable as well as the cable itself. good luck

[baja200merk]

Make sure the VST is not overflowing

[jeffg]

Vts float problem would give a burst,buttery moving would not.Im a backyard merc 2 stroke v6 person,cant help myself.I have bought probly 30 problem optis and have gotten to know them by comparison.I have had a few do this and its the tps.It not bad enough to throw a beep,just a little bad spot from idling in my opinion.I have actually move the trottle stop up a tiny and let the computer ujust voltage on start up.Its like a old radio volume control that gets scratchy.I would still also suggest checking your throttle cable pretention.If its not parking snug,this is your problem.Once again,good luck.I dont own a ddt for what its worth.

[stan73]

Thanks I will try the TPS sensor first. need to wait till the snow leaves up here.

[jeffg]

If you snap the linkage rod off the tps and manually work it back and forth 20-30 times,may clean it up.Bur please check pretention.Pretention is ajusting the throttle cable so it makes the throttle are seat to the stop snug but no overkill.it doesnt take but a little to let the voltage stay increased.A little voltage equals rpms.I figure a few minutes tinker is cheaper than throwing parts.

[stan73]

thanks good to know

[Duro78]

Willing to bet it's your tps I had the same exact issue with my opti 250xs. Changed it out and problem solved, seems to be a common issue with the opti's

[stan73]

Good to hear, looking forward to spring to try it with a new sensor

[stan73]

Got it (FIXED) It was the TPS sensor ! Computer sets the V of the TPS upon Key up, when the TPS is dirty the voltage may be differnt when it returns to neutral
and the motor revs high, reset is accomplished by turning key on and off....which locks in the new Voltage

[jeffg]

Im glad you got it.I kinda new it from messing with a bunch of them.I own a scanner now but seldom grab it.Be certain to ask your local merc dealer about your injector service.I dont know your hours but injector and compressor service by mercury standards will bring much promise to a long life.Many miss there clean burning strong running opti after buying 4st.Once again,glad you got it.Have a good summer