Optimax at idle is racing

[HUMBER P4VWL]

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]

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]

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]

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]

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]

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]

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]

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

[iainmartins]

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]

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?