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ProStar Slalom
04-05-2008, 11:28 AM
Opening day for me today, and first day skiing with the new-to-me 2001 19 Skier. Overall, ran great, but was idling a little fast. Varied from pass to pass, but averaged about 800 in gear and 1,000 in neutral....so about 200 RPM fast. Is there a way to adjust the idle on a TBI engine? 310 Hp Predator. Thanks for the help.

Engine Nut
04-05-2008, 12:13 PM
[QUOTE=ProStar Slalom]Opening day for me today, and first day skiing with the new-to-me 2001 19 Skier. Overall, ran great, but was idling a little fast. Varied from pass to pass, but averaged about 800 in gear and 1,000 in neutral....so about 200 RPM fast. Is there a way to adjust the idle on a TBI engine? 310 Hp Predator. Thanks for the help.[/QUOT

There is no way to adjust the idle RPM. Idle speed is a functon of the calibration in the ECM that runs the engine. The rpm change from neutral to in gear is not normal. I would take the boat to a dealer and have them hook up a scan tool and check the sensor parameters ... particularly the TPS (throttle position sensor). I suspect the TPS has a fault.

flipper
04-05-2008, 12:23 PM
That's what I was thinking....only other thing I can think of is the timing is way advanced, or the throttle cable is too short.

ProStar Slalom
04-06-2008, 07:10 AM
Thanks for the replies. Throttle cable adjustment seems fine. Engine Nut, after your response, I had to think a little....I'm not sure it was dropping when going into gear, but I do know that the RPM varied quite a bit when stopping between passes. Tough conditions yesterday with rain; hope to ski again today and I'll do a better job of noting what's going on.

ProStar Slalom
04-06-2008, 08:38 PM
Ok, ran the boat again today. It doesn't really vary with neutral versus in gear at idle. But, it did vary throughout the afternoon. For the most part, it was fine...around 600 or so, but there were other times when it did creep up to 800-1000 for no apparent reason. I checked the linkage at the TBI and the arm was against the stop, so it's not the throttle cable.

Engine Nut, does this mean a calibration is required, or a component replacement, or both? Thanks.

Jerseydave
04-06-2008, 08:53 PM
Just a guess, but maybe check for a vacuum leak or a vac. hose that may have got knocked off?

Engine Nut
04-06-2008, 08:59 PM
Ok, ran the boat again today. It doesn't really vary with neutral versus in gear at idle. But, it did vary throughout the afternoon. For the most part, it was fine...around 600 or so, but there were other times when it did creep up to 800-1000 for no apparent reason. I checked the linkage at the TBI and the arm was against the stop, so it's not the throttle cable.

Engine Nut, does this mean a calibration is required, or a component replacement, or both? Thanks.

It is not likely that it is a calibration issue.If it was, it would have acted that way since day 1. Calibrations within an ECM do not change over time. A scan tool connected to the engine should give a technician the info needed to determine what component might be causing the problem. I would look at the TPS sensor, the MAP sensor and the IAC values.

JimN
04-06-2008, 09:39 PM
If the throttle cable is removed from the throttle body, assuming there's no Perfect Pass or anything like that to restrict throttle plate movement, it should go to normal idle speed by resting on the idle stop. If the idle is still too high, start looking for vacuum leaks. The PCV hose is a good beginning, and the MAP sensor is another one to look at. It's also possible that the MAP sensor is leaky. Pinch the MAP sensor tube and see if anything changes. Also, look at the MAP sensor tube to see if it has any liquid in it, especially if the ECM is mounted at the side of the motor, below the valve covers. If these don't shed any light on it, make sure the throttle body is tightly bolted to the intake manifold and the manifold gasket doesn't have any obvious gaps. If the throttle body or intake manifold have ever been removed, make sure the bolts are tightened to spec.

If you want to check for gasket leaks, get a can of carb cleaner and spray it along the intake manifold on both sides, and around the throttle body base gasket. Make sure the IAC bolts are tight, too.

If these don't solve anything, make sure the IAC is functioning correctly. If it hangs up when it's supposed to be closing, the idle will be too high. Make sure it closes when the key is turned off and then reopens a bit.

ProStar Slalom
04-07-2008, 05:47 PM
Jim,

I'm tracking with the PCV valve portion, but you lost me with MAP sensor. Can you dumb it down a little for me? What it is? Where located? Thanks.

JimN
04-07-2008, 07:55 PM
There's a thin, clear vinyl tube that goes from the throttle body base to a black plastic sensor. The hose attaches on one face and there's a three-wire harness plugged into it. MAP stands for Manifold Absolute Pressure and it sends the barometric pressure and vacuum info to the ECM to indicate the load on the motor. If the tube doesn't fit tightly or is cracked, it will cause a vacuum leak and the idle speed will be too high.

Follow the plastic tube and it'll lead you right to the sensor.

ProStar Slalom
04-08-2008, 08:24 AM
Thanks, Jim. Now you're talking at my level. I'll take a look....

ProStar Slalom
04-28-2008, 06:51 AM
Still playing with this because I'm too stubborn/lazy/cheap to take to the closest dealer 2+ hours away. I've checked the PCV and MAP hoses, as well as the TBI base....doesn't seem to be an air leak anywhere. The high idle has become less common over the past couple weekends of use, but still happens from time-to-time. If it's idling high, my solution has been to turn the boat off, let it sit for 30 seconds, and start it back up.....brings it right back down to the right idle RPM. Does this help any of you smart guys with a diagnosis? If it might be the TPS, is it a cheap/easy replacement for troubleshooting? Thanks again....

JimN
04-28-2008, 06:57 AM
If you don't have a check engine light, it's probably not the TPS. If you didn't check the IAC (Idle Air Control) motor, do that, since that's what functions the engine speed at idle, through commands sent by the ECM. It is possible for the IAC function to be bad in the ECM but I have only seen one do that. Get some stick pins and insert them in the IAC plug, then connect a test light to the blue pair to make sure it lights up and then repeat with the green pair. If it doesn't light up when the problem exhibits, check the harness and terminals.