View Full Version : LTR Engine Start...High RPM

03-28-2006, 05:05 AM
2001 LTR Motor, immediately after starting the motor, it will climb RPM's...AND, the RPM gauge does not work. I would say it gets up to about 2500, 3000 rpm's. Throttle in neutral, checked 'slack' on cable, perfect pass tightened. Throttle Position Sensor? :confused:

88 PS190
03-28-2006, 08:07 AM
Does it go back down or stay up there?

03-28-2006, 08:57 AM
Thanks for the response....

I attempted about 4 or 5 starts. Every one stayed high on the rpm. The last attempt I let run about 5 secs. The motor fairly 'smoothly' kept climbing higher on the rpm's. They never 'fell' back down.

Also, I took the air filter off and verified the butterfly was closed...or at near close.

03-28-2006, 09:09 AM
Is there any gap where the perfect pass cable and the throttle cam are connected? Next step would be to check the IAC motor if the throttle is really closed.

03-28-2006, 09:28 AM
Thanks Mike....you think the IAC is a higher probability over the TPS?
Found this:

"The IAC valve affects only the idle characteristics of the vehicle. If it is fully retracted, too much air will be allowed into the manifold and idle speed will be high. If it is stuck closed, too little air will be allowed in the manifold, and idle speed will be too low. If it is stuck part way open, the idle may be rough, and will not respond to engine load changes."

I realize to find the right sensor...you kinda need to hook up to the laptop.

03-28-2006, 09:48 AM
..almost forgot...Would this matter:

On top of the valve cover, starboard side, is about 1/2" hole with about a 2-3ft. rubber hose attached that ran up to the air filter. The end of this hose had a metal attachment with clip. I could not find if/where it was suppose to be hooked into something. It was not attached to anything. I thought it was more of an 'exhaust' for the valves...rather than a vac line.

88 PS190
03-28-2006, 10:07 AM

03-28-2006, 10:12 AM
Valves don't need an exhaust, but if you ever wondered what a PCV valve was for, it's to get rid of cumbustible gases in the crankcase, which go through a hose to the intake, through a valve that is spring loaded, to maintain correct idle. As the RPM increases, vacuum below the throttle plate decreases and the valve closes slightly. This hose attaches to the intake, just below (after) the throttle body. It will maintain its shape after being on the motor and you should be able to find a short tube that it can go on. Who worked on the boat last?

xbrdr1- The IAC usually won't go to its wide open point unless it's told to. You can hear it "parking" in the 3-5 seconds after turning the key off, if you listen for it with the motor cover opened. If the TPS goes bad, throttle response quality decreases and the ECM will default to 12% throttle position, with the motor operation being taken over by the MAP sensor. ALl the TPS does is let the ECM know if the motor is at idle (2% or less throttle position) of if there is a +/- 20% change, the fuel mix is enriched or leaned out, respectively. It could also be used to go to WOT for clearing a flooded intake, something that's very rare with injection.

A bad TPS will give you a code (21 or 22) and the check engine light should go on. If the hose going to the valve cover has no PCV valve on it, this would definitely cause the high RPM issue because it constitutes a major uncontrolled vacuum leak.

03-28-2006, 10:24 AM
JimN...great information. Thanks for the reply.

This picture should work:

OK, the line (#27 in the pic below), it does have the clip (#28), on the end. That line is suppose to attach to the PCV?


03-28-2006, 11:04 AM
Take a pic of your motor and post it here. It'll be more helpful.

03-28-2006, 11:06 AM
After re-reading your post JimN..

The hose connection at the valve 'appears' to be OK..and it is connected. I assume is has the pcv in it. The other end of the tube is not connected. It has a metal round fitting in it.
I checked around the air intake (KN in this case) to find a place to where it should attach. Did not find anything, and wondered if it was only suppose to release 'vapors' into the motor box area.

03-28-2006, 11:28 AM
That clip actually slides under the airfilter clamp, so it holds the open end of the hose close to the airfilter. I guess it just draws the venting exhaust back into the airfilter.

03-28-2006, 12:05 PM
Gotcha...thanks Tom. That musta came off when I popped the air filter off. So, I guess that line is not the issue.

03-28-2006, 01:42 PM
OK..can anyone verify this...

I was just told (reputable source) that the Indmar computer wire port can be 'paper-clip' jumped for the check engine light code.

I use to do this in the 95 Blazer...worked great everytime.

03-28-2006, 07:49 PM
Are you sure your linkage is back to the minimum position?
I doubt a faulty sensor could make the engine rev that high(2500-3000 rpms) without giving it some air and gas ot there is something i don't understand if your butterfly stay close...

03-29-2006, 02:37 PM
Andre, I think you were on the right track....I 'broke down' and dropped it off at the dealer this morning. Turned out that although the throttle cable was in the 'bracket' and 'free' to move...it was not properly seated/situated/locked in to the bracket. Thanks everyone for the posts.