Optimax at idle is racing

HUMBER P4VWL · 30 July 2009, 12:27

Year old 175 opti is fine trawling and running round and at idle most of the time.

I have found though that when i put it in neutral it races, ie revs surge up and down and up and down and up and down etc. If selecting a gear when racing it obviously doesnt do the gearbox any good.

It doesn't always happen, sometimes it idles perfectly. Im going to mention it to the dealer when i take it out at end of season and ask them their thoughts when they winterise it.

Has anyone else come across this ever?? If so, what was it? I'm guessing with very basic knowledge it may be the automatic choke in some way shape or form.

PeterM · 30 July 2009, 12:46

Sounds like if you use the fast idle lever ( in neutral) - I think there is a rev limiter ( about 2k in Neutral on mine) built in - does the gauge show an ' overspeed' alarm ?

Possible the lever is getting caught somehow inside the control box as you come back to idle power/ neutral ?

Ribshop · 30 July 2009, 13:23

most of the time this is caused by the throttle position sensor on the Optis, it might need freeing up or the link are adjusting

HUMBER P4VWL · 30 July 2009, 13:49

we have top mount controls that dont have the idle lever so it isnt that which is getting caught.

Could be the throttle positon sensor, hence the intermittent occurences. Will ask the dealer to check it out.

Thank you both for your comments. Whilst im sure the dealer will be aware of the issues, it is always useful to point them in the right direction, especially if the problem doesnt occur when they try it!!!

HUMBER P4VWL · 30 July 2009, 13:50

Quote:

Originally Posted by Blackroady

Sounds like if you use the fast idle lever ( in neutral) - I think there is a rev limiter ( about 2k in Neutral on mine) built in - does the gauge show an ' overspeed' alarm ?

Possible the lever is getting caught somehow inside the control box as you come back to idle power/ neutral ?

There are no alarms going off. At idle it is normally about 500-700 rpm but it surges up to 1300 when it does it.

uncle al · 30 July 2009, 20:29

as it is probally under warranty it will need to go to a dealer with the diagnostic equipement as it could be one or two maybe small problems (sensor maybe or set up?)

Rodan · 30 July 2009, 22:07

Had same problem and for me it turned out to be the way the throttle cable was fed through into the engine, at some positions of the engine there was enough friction on the outer cable to move it slightly and put a mimimal bit of throttle on...

HUMBER P4VWL · 30 July 2009, 22:10

Cheers for your comments, the more potential problems/solutions that people give the more likely it will get resolved.

iainmartins · 09 August 2009, 17:21

My 150 opti has been doing the same thing. The smartcraft gauges now say TPS sensor fault, can I leave it until the end of the season or should I stop using it?

HUMBER P4VWL · 09 August 2009, 21:45

good to hear someone else has the problem...sort of. What is the TPS unit?

Can anyone comment on the question, can i wait until the end of the season?

iainmartins · 09 August 2009, 22:42

I thought TPS was throttle position sensor. I am going to phone the dealer and ask what he thinks. Have been told there are 2 so it should be ok but don't quote me on that.

HUMBER P4VWL · 09 August 2009, 22:54

Quote:

Originally Posted by iainmartins

I thought TPS was throttle position sensor. I am going to phone the dealer and ask what he thinks. Have been told there are 2 so it should be ok but don't quote me on that.

Yes others have mentioned the tps. Let me know how you get on. I'm going to wait till sept when we take it out, unless problem occur.

HUMBER P4VWL · 20 October 2009, 14:38

Well the boat's out of the water and had its service.

More recently, the engine was only revving to 4800 rather than over 5000 and the top speed down to 34mph! With engine still racing at idle.

Evidently though, unlike the general forum consensus of it being the TPS, an alternator bolt had snapped. Quite how, i have no idea, the cowling hasn't been off and nothing has been hit all year. ABC marine in Anglesey who did the service have said that it now runs fine. They also alluded to coming across the problem before on the V6 optis. Seems strange.

Anyone else had this?

Rogue Wave · 20 October 2009, 15:06

Not on the smaller 150 but I snapped an alternator bolt on a 200 and I was on a boat that snapped the ol pump off on a 225, we were having fun at the time however!

iainmartins · 20 October 2009, 15:26

Had exactly the same problem it is a common fault.

HUMBER P4VWL · 20 October 2009, 16:22

Quote:

Originally Posted by iainmartins

Had exactly the same problem it is a common fault.

Did you have the same symptoms?

How does it snap? From engine vibration/design fault or from "having fun"? We did have it airborne a few times whilst going round Anglesey.