Oscillating RPM

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Richard Swails

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#1
I have a 2001 Subaru Outback LL Bean with the H-6 engine and auto transmission with 40k miles. Around town I drive in 3rd gear instead of "D". If I let up on the gas the tach will drop to about 1k and start to oscillate between 1k and 1.5k. I asked the dealer about it and they had no explanation. Has anyone had a problem like this before. I found TSB 118006. The summary says: "Throttle Position Sensor. Vehicles equipped with H-6 3.0L engines."

Any help is greatly appreciated.
 
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#2
I would clean the throttle body, and I would also clean the idle air control plunger and the bore it rides in. Besides that I would check for vac. leaks. Cleaning the throttle body will not harm anything (don't mess with it if its a drive by wire) you should be good as long as you have the traditional cable that pulls the butterfly open. Had a car in just the other day where the battery was replaced and it would not idle. Clean the IAC and it was good to go.

Ford_Dude
 

jjm

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I can't find any TSB's by that number - nor anything relating to the TPS. The only fuel system TSB on this vehicle relates to fuel pump assembly parts. Not that any of this matters anyway... a TSB is only a piece of paper... it doesn't come with tools and it can't fix your vehicle. If it could, we wouldn't need mechanics... just send out a bunch of faxes to vehicle owners.

Is the malfunction indicator lamp / check engine lamp on? Did you scan the vehicle for codes, including "soft" or pending codes?

You could also try THOROUGHLY cleaning the throttle body using THROTTLE BODY CLEANER (not carb cleaner). A lot of times that can cause unstable RPM's on the lower end.

It would also be a good idea to get rid of the Kerry/Edwards, Bush Lied, and Save The Earth bumper stickers that invariably are plastered on Subaru's.

Joe

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Richard Swails

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#4
Thanks for the info. I might be confused about the TSB. What I found were two numbers under the same search. They are: " NHTSA Item Number: 10020697" and "Service Bulletin Num: 118006". It also said "Date of Bulletin: Nov 08, 2006".
 

jjm

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Figures... that's why I couldn't find it. NHTSA are not TSB's... all NHTSA is a government bureaucracy, and the information you're seeing is nothing more than complaints. If enough people complain they don't like the paint color, it'll probably get a NHTSA bulletin. They know nothing about cars, and even less about repairng them.

If you want the real factory information, you might consider an <a href="http://www.myaffiliateprogram.com/u/alldata/t.asp?id=1035">AllDataDIY</a> sub... basically the factory shop manual, with updates, TSB's, part numbers, labor times... a well worth it investment if you plan on doing your own work.

As Ford_Dude and I noted, try cleaning up the throttle body first.

Joe

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Richard Swails

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Jim: Thanks again. I'll do the throttle body first. I've also removed all the usual liberal bumper stickers and replaced them with NRA and Marine Corps stickers.
 

jjm

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I've also removed all the usual liberal bumper stickers and replaced them with NRA and Marine Corps stickers.
Good man! I bet it's running better already!!!

After cleaning the throttle body, it's a good idea to clear the PCM and allow the engine parameters to be "relearned." This can be accomplished by either disconnecting the negative battery cable for about a minute (you'll likely lose your radio settings) or pulling the PCM fuses (a more "elegant" approach) also for a minute. After reconnecting, allow the engine to idle for 5-10 minutes before driving. Engine may act erratically for a few hundred miles until the PCM becomes re-edumucated. But should be good after that. If problem is gone, you know it was the TB. If not, post back and we'll take it from there.

If you don't clear the PCM, often the problem remains, or takes a LONG time to correct itself.

Joe

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