GT40 - intermittent high idle

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   Hi all,

I had some surging issues.  Had planned to clean the IAC valve but before doing that I noticed some 'slop' in the throttle linkage.  It was mainly due to the perfect pass which is currently non functional - it is still connected to the throttle though.  The throttle linkage has been reconnected and the slack taken out of the system at the perfect pass servo motor and hey presto, no more surging.

After some running this weekend I noticed that upon returning to idle (out of gear) the rpms were around 1100/1200 on some occasions.  Upon putting it into gear the rpms drop to 700 or so as expected.  She runs fine otherwise.

Could my throttle linkage adjustments be causing this?  My girlfriend had been driving most of the weekend and did not notice this but on Sunday I was pulling some people and I spotted the symptoms.

The boat is 60 miles away so I can't get a look at it before the weekend.

All advice welcome - as usual!

D.

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2001SAN Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-26-2012 Location: Ireland Status: Offline Points: 246	Post Options Post Reply Quote 2001SAN Report Post Thanks(0) Quote Reply Topic: GT40 - intermittent high idle Posted: July-09-2013 at 9:14am
	Hi all, I had some surging issues. Had planned to clean the IAC valve but before doing that I noticed some 'slop' in the throttle linkage. It was mainly due to the perfect pass which is currently non functional - it is still connected to the throttle though. The throttle linkage has been reconnected and the slack taken out of the system at the perfect pass servo motor and hey presto, no more surging. After some running this weekend I noticed that upon returning to idle (out of gear) the rpms were around 1100/1200 on some occasions. Upon putting it into gear the rpms drop to 700 or so as expected. She runs fine otherwise. Could my throttle linkage adjustments be causing this? My girlfriend had been driving most of the weekend and did not notice this but on Sunday I was pulling some people and I spotted the symptoms. The boat is 60 miles away so I can't get a look at it before the weekend. All advice welcome - as usual! D.
	A little knowledge is a dangerous thing... 2001 Super Air Nautique 1989 Fairline Corniche 31 www.bannrivercruises.co.uk

Bri892001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947	Post Options Post Reply Quote Bri892001 Report Post Thanks(0) Quote Reply Posted: July-09-2013 at 7:11pm
	There are other things that may cause a high neutral idle such as a vacuum leak on the intake. But, I'm curious about how the Perfect Pass slop was taken out? I ask because, turning the little knob on the servo motor is a temporary fix. If the motor is disabled and isn't able to "feel" for slop as part of its start-up routine, the slop will keep coming back. Although, the symptom I'm familiar with is reduced top speed, not high idle. See if the throttle linkage, the part that's directly connected to your throttle body is able to return to the fully closed position. Meaning, make sure nothing in the cable is keeping it partially open.

2001SAN Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-26-2012 Location: Ireland Status: Offline Points: 246	Post Options Post Reply Quote 2001SAN Report Post Thanks(0) Quote Reply Posted: July-10-2013 at 8:46am
	Hi Brian, The throttle linkage had slipped out of the L shaped bracket where it meets the cable from the PP. I popped the threaded bit through the bracket again and tightened the brass nuts on either side. I then turned the knob on the PP motor to take the slop out. It did leave the throttle very 'tight' for lack of a better word. By that I mean that as soon as I put her in gear I was into revs. A delicate touch was needed around the dock and when taxiing with a skier. Maybe this is linked to the high idle? You think I should disconnect the PP altogether while its out of use? I don't think I have any other signs of a vacuum leak (based on my 'Googleing')- but then again what I don't know about engines could probably fill a book! D.
	A little knowledge is a dangerous thing... 2001 Super Air Nautique 1989 Fairline Corniche 31 www.bannrivercruises.co.uk

Bri892001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947	Post Options Post Reply Quote Bri892001 Report Post Thanks(0) Quote Reply Posted: July-10-2013 at 12:53pm
	It sounds very likely that your tight throttle could be related. I'd say you want to rule that out before moving forward to other diagnosis. I'd be curious to see pics of the PP setup. Taking out the PP altogether might be a good idea if you're not planning to fix it. Do you know what's wrong with it? If you poke around the support section of http://www.perfectpass.com/ there's some decent diagnosis videos and you might get some ideas. Are you getting display activity but not motor function? PP is nice to have for wakeboarding, but it can make throttle cable adjustment a little tricky.

2001SAN Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-26-2012 Location: Ireland Status: Offline Points: 246	Post Options Post Reply Quote 2001SAN Report Post Thanks(0) Quote Reply Posted: July-11-2013 at 12:29pm
	The PP module is toast. The previous owner mounted it in a position that allowed rain water to get into it. I plan to replace the module in the off season, too much money at the mo. I'll take a pic of the throttle linkage at the weekend and see if some minor adjustments sort the idle out. It would be a major coincidence if the two weren't related. We have unprecedented good weather here at the moment so should be on the water all weekend which will give me plenty of time to have a fiddle with it. enjoy the weekend.
	A little knowledge is a dangerous thing... 2001 Super Air Nautique 1989 Fairline Corniche 31 www.bannrivercruises.co.uk

Bri892001 Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947	Post Options Post Reply Quote Bri892001 Report Post Thanks(0) Quote Reply Posted: July-11-2013 at 1:05pm
	Boston weather looks like Ireland is supposed to right now. New Hampshire is expecting decent weather for Sunday though. Enjoy the weekend as well.

2001SAN Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-26-2012 Location: Ireland Status: Offline Points: 246	Post Options Post Reply Quote 2001SAN Report Post Thanks(0) Quote Reply Posted: July-15-2013 at 11:24am
	well, it was the PP. too tight at the servo motor end. i backed it off and was good to go. still have a little bit of a rolling idle (out of gear) so will clean the IAC as soon as possible. d.

GT40 - intermittent high idle

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