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mzito
08-03-2010, 11:10 PM
I have a 1995 Pro Star 190 with a 350 275HP EFI with a power slot tran. The last few times out I have noticed that RPM's jump to 970-1100 when I shift into neutral. The RPM's usually run around 650-690 in neutral. This problem is not consistent, it only happens sometimes. If I shut the engine off and restart sometimes it will bring the RPM's back down sometime it doesn't work. I am confused with this one. Any help is appreciated.
Thx
Matt

dgaugler
08-15-2010, 03:59 PM
I'm having a very similar problem on my '96 Maristar with the 285hp TBI engine. My started the season with a little bit of a rough idle but with RPMs at around 650-700. Now it is idling at 1100 RPMs most of the time and running really rich. I replaced the IAC ( Idle Air control) but it is still idlingat 1100 a running really rich and if you open the throttle to fast it bogs out. (might be because the plugs are fouled now.) Anyone have any ideas?

dgaugler
08-15-2010, 07:17 PM
I know most of you on here are against just buying and replacing parts until you fix the problem, but it worked for me today. Solved the running rich and high idle problem with just $75 worth of parts. I replaced the IAC (Idle Air Control) and the TPS (Throttle Position Sensor) and it's running like a charm. I think it was the TPS that was the main culprit but she's running smoother than ever now so I think the new IAC may have helped clean that up. If you have a TBI (Throttle Body Injection) engine that is running rough, running rich, or has a high idle I think I would just replace these two parts and see what happens.

mzito
08-15-2010, 08:46 PM
I know most of you on here are against just buying and replacing parts until you fix the problem, but it worked for me today. Solved the running rich and high idle problem with just $75 worth of parts. I replaced the IAC (Idle Air Control) and the TPS (Throttle Position Sensor) and it's running like a charm. I think it was the TPS that was the main culprit but she's running smoother than ever now so I think the new IAC may have helped clean that up. If you have a TBI (Throttle Body Injection) engine that is running rough, running rich, or has a high idle I think I would just replace these two parts and see what happens.
Thanks for the info I will look at replacing those two parts. Today my MC ran like a top, but yesterday the idle was high. I will try your suggestion and let ou know how it goes.

Thanks,
MZ

Tom Jones
08-15-2010, 08:58 PM
Where did you get the parts so cheap?

JimN
08-15-2010, 09:00 PM
I have a 1995 Pro Star 190 with a 350 275HP EFI with a power slot tran. The last few times out I have noticed that RPM's jump to 970-1100 when I shift into neutral. The RPM's usually run around 650-690 in neutral. This problem is not consistent, it only happens sometimes. If I shut the engine off and restart sometimes it will bring the RPM's back down sometime it doesn't work. I am confused with this one. Any help is appreciated.
Thx
Matt

Find out if the parts are actually bad before replacing them. The TPS can be checked with a multi-meter.

Remove the throttle cable from the throttle lever- if it stays at normal idle, it's definitely not the IAC and TPS. You need no tools to disconnect the throttle cable.

Tom Jones
08-15-2010, 09:04 PM
Hey Jim,
my boat is doing this very same thing. restarting usually corrects it.
i had written it off to a perfect pass issue.

JimN
08-15-2010, 09:06 PM
On a 15 year old boat, I would make sure the throttle cable isn't binding- they do that and it doesn't always take that long to begin. Disconnecting the cable just removes one more possible cause from the list. Sometimes, the cable just needs to be adjusted.

Tom Jones
08-15-2010, 09:15 PM
Actually my profile is not correct.
I now have a 2004 197 with TBI
I have adjusted the cable and it seems to move freely when the PP is disconnected.
With it connected I can feel the throttle stick just before neutral.
Do you think it is the PP cable that could be sticking? It is only a year old.

JimN
08-15-2010, 09:40 PM
Actually my profile is not correct.
I now have a 2004 197 with TBI
I have adjusted the cable and it seems to move freely when the PP is disconnected.
With it connected I can feel the throttle stick just before neutral.
Do you think it is the PP cable that could be sticking? It is only a year old.

At only a year old, it probably just needs adjustment.

dgaugler
08-15-2010, 11:39 PM
I got the parts at the local Oreilly's Auto parts store. Only trick was I came with the part numbers because the parts for a GM pickup for the same year tend to sometimes be different. I looked online and the parts were considerably more expensive.

You have to be careful about just testing your TPS, just becasue it's returning some voltage doesn't mean it's the right voltage. Mine was still working just reporting that the the throttle is further open than it actually was at an idle. I think mine was just inconsistent because at times it would have rough idle, then a fast idle sometimes 900 RPMs then 1100 RPMs.

rwassman
08-16-2010, 04:32 PM
I had (have) the exact same problem on my '96 Prostar with 350 TBI. I took out the IAC and cleaned it with ether (didn't have carb cleaner handy). There was just a little bit of carbon in the throttle body - a few flakes. Since then it's only happened once and I cleaned it about five weeks ago.

mzito
08-17-2010, 06:32 PM
Well, I just changed the TPS and all seems well. The RPMs are normal now when in idle. 75.00 part well worth it.
MZ

Tom Jones
08-17-2010, 09:48 PM
Question for JimN
How do you test the TPS with a multi-meter
What are the values?

JimN
08-17-2010, 10:00 PM
Question for JimN
How do you test the TPS with a multi-meter
What are the values?

It has a three wire harness with a blue, a black and a gray wire. The black is connected to ground, the gray has a 5VDC reference voltage and the blue is the return to the ECM and should have 2-4.5VDC, depending on throttle position.

Am multi-meter will rarely show a glitchy TPS- the transients are too fast and occur over a really short time period, which a meter isn't made for. To really see a glitch from a TPS, a digital storage oscilloscope is needed.

JHogins
08-28-2010, 12:20 PM
I was having the same problem - idle would not come down below 1,100 rpm on my '94 Maristar 350 TBI. Cleaned the IAC valve but that didn't seem to help. Replaced the TPS and now we are back to a nice and smooth 650 rpms. The TPS cost ~$33 at O'reilys. Me Happy!
Thanks...
Jon

mcxfan
09-04-2010, 11:35 PM
Hey Guys, what are the steps to replace the TPS on an Mcx? I have an 06 X2 and I am having the same issue. Thx

JimN
09-05-2010, 12:19 AM
CHECK FOR CODES! The sensors cause codes to be stored in the ECM and that's how it's determined if you have a bad one. The IAC isn't a sensor but it could be sticking, which will cause the high idle. Make sure the TPS is actually bad before replacing it.

Engine Nut
09-05-2010, 09:14 AM
Your 06 model has electronic throttle control so there is no IAC valve. It does have a TPS but it is not the same as the TPS on a TBI injected engine or on a multi-port mechanical mono-valve. The signal that controls your engine speed comes from the PPS (pedal position sensor) also referred to as a throttle control potentiiometer. If the TPS or the PPS have a problem it will set a code and light the check engine indicator in the boat. If the TPS is bad you have to replace the whole mono-valve assembly. If the PPS is bad you have to replace the throttle/shift control assembly.

Hey Guys, what are the steps to replace the TPS on an Mcx? I have an 06 X2 and I am having the same issue. Thx

mcxfan
09-06-2010, 11:27 PM
I assume I will have to take it to the dealer to pull the codes. I was hoping this could be a DIY fix. Engine Nut, do you think this is the case???

brad
07-22-2011, 03:42 PM
Does anyone know the part # for throttle position sensor for a 04 prostar TT