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View Full Version : Am I missing a throttle return spring?


Jeff d
04-22-2011, 02:14 AM
I installed Perfect Pass Stargazer on my '00 230 VRS w/ the LTR a couple of months ago.

Overall it works great but if the driver is not careful with how far they open the throttle Perfect Pass has a hard time gaining control of the speed. When it does overshoot the speed it tends to bounce around the setpoint a lot before settling down. Once it settles down it's pretty much perfect.

My only experience w/ PP was on throttle by wire boats which never did this so I had just been chalking it up to the servo not being as good as direct control via the computer

Last time out it was overshooting by 6-8 MPH sometimes which got a bit scary for some of the inexperienced boarders so I decided to look into it a little. In the troubleshooting section of the PP manual it suggested that this could be due to a weak throttle return spring. This seemed pretty logical.

I checked the large coil spring that goes around the shaft of the butterfly valve and it seems ok at a glance (No obvious damage or anything but I will have to disconnect the cable to check how good it really is) but I noticed that there was what appeared to be a perfect spot where a supplemental spring should be connected.

See the red arrows in the attached pic. There's a hole in the rotating plate opposite where the throttle cable attaches (Not sure what to call this) then there are 2 rows of 3 evenly spaced holes on the bracket that supports what appears to be the ECU and other electronics for the engine. It looks like these holes would be to provide tension adjustability without having to change springs.

On top of this I have faint memories of finding a spring in the bottom of the hull last year when I bought the boat but this could just be my mind messing with me.

So, should there be a spring there? If so I figure I can find a suitable one at an auto parts store but would the one from MasterCraft be SS or anything fancy?

Thanks,
Jeff

Jeff d
04-22-2011, 10:20 AM
I disconnected the cable and moved the throttle plate by hand. The large spring that's coiled around the shaft feels like it has good strength but I'm not sure how much resistance to closing the airflow at 2/3-3/4 throttle would provide.

kskonn
04-22-2011, 11:59 PM
I had this problem last year and it turned out to be my throttle return spring. it needed to be cleaned and was not responsive. Basically I would overshoot the speed, the stepper motor would keep stepping down and then the spring would finally give making the boat slow down to much and then it would slowly work its way back up and hold pretty well. Once I fixed the spring it works great. Overshoots by about 1-2 miles and immediatelly locks in to the speed.

Jeff d
04-23-2011, 12:51 AM
I played with it today some. I had the servo mounted on the port side cooling hose as shown in the PP installation manual. It seemed fine there even when turning the knob by hand but I had no point of reference to compare it too since I just mounted it there during install, tested it with the knob and it seemed ok. It looked like it may have been putting the L bracket in a bit of a bind though so I temporarily moved the servo to the port side exhaust manifold hose. Right away I noticed it moved a lot smoother.

So, I got a hose clamp and mounted the servo on the exhaust hose. I lubed up all of the pivot points of the throttle body and the PP cable with Teflon spray lube and it moves a lot better now. I will test it on the water tomorrow and see how it does.

One other "tip" for installing the perfect pass servo that might be helpful: I found it much easier to get a feel for any friction in the cable/L bracket by loosening the knob/string up and pulling the cable with your fingers. I found it hard to tell the difference when winding the knob but it was painfully obvious when manipulating the cable from the servo end with my fingers. A little bit of a bind and I could barely pull it while cranking the knob didn't feel much harder.

Jeff d
04-23-2011, 10:03 PM
Well, despite lubing everything and relocating the servo for less drag in the cable it's still acting the same way. Can anyone take a quick look at their LTR and see if it has a spring where the red arrows are in my pic above?

Thanks,
Jeff

Stutsman230
04-25-2011, 12:38 AM
I have a 2002 Maristar 230 VRS/LTR with Perfect Pass installed. It is the satellite version. There are no additional springs. I do find that the speed will overshoot quite a bit if the driver gives the boat too much throttle and doesn't throttle it back a bit when the PP takes control. I have a PS190 with the old paddlewheel PP and it has a faster response and excellent control but that boat weighs 1500 lbs less. I will attempt to post pictures I took tonight.

Jeff d
04-25-2011, 10:15 AM
Thanks for the pictures. Your engine looks nicer than mine. I need to clean some stuff up and paint it.

I had my servo mounted like yours and it always bothered me that the cable housing tended to pull the L bracket towards the rear. Here's a picture of how it's setup now. I can feel less friction in the cable and the L bracket sits perfectly perpendicular to the throttle cable and servo cable.

Stutsman230
04-28-2011, 12:13 PM
I like the idea of the straight pull! I'm going to follow your lead. Maybe it will reduce the overshoot or at least help the sensitivity.

Jeff d
04-28-2011, 12:25 PM
I just loosened one of the existing clamps and slipped the servo under it. Then I put another 4" SS hose clamp on the other side of the servo (Not shown in that pic).

I emailed with Perfect Pass and Aaron said that what I described is pretty typical behavior especially with a "stronger engine like the LTR" and the driver will have to control the overshoot manually.

I'm wondering if messing with the KDW setting would have any effect on this.