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Car: 2008 Tribeca, 2010 LGT, Sold: 2005 XT Limited
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Discussion Starter #1
I've been investigating a slightly rough idle when warm. I was wondering if it was a 'drive' vs 'neutral' issue related to drive shafts. What i noticed is that the RPM drops about 100-200 rpm (if I am reading the low end of the gauge correctly) when in drive and gets slightly rough. No issue when cold.

Is this normal? I can't seem to recall this from before. Any suggestions?

Thanks!

Tom
 

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Premium Member
2001 VDC/SC One of a Kind
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14,436 Posts
The engine rpm drops when you put it in D because it creates a load. In P, it should idle about 750, in D 600-650.

If the idle is rough in D while stationary, it could be a number of things: Axles, motor or transmission mounts, loose suspension parts, poor fuel delivery, clogged PCV valve, dirty throttle body are just a few.
 

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Car: 2008 Tribeca, 2010 LGT, Sold: 2005 XT Limited
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Discussion Starter #3
Okay. I noticed it shortly after changing the timing belt, replacing the boot on the original drivers side and a full transmission fluid flush (Subaru HP ATF). Maybe that axle is worn and putting it in with different mating splines it is no longer up to snuff.

It's pretty minor.

I'll try replacing the PCV and cleaning the throttle body and MAF. If it's not better, I'll wait for it to get worse before I do anything else. Those should be done anyway.

Thank you for the reply!

Tom
 

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05 OBXT 5eat stg1.2
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2,105 Posts
If it happened immediately after a timing belt job, then check for vacuum leaks. Maybe something got knocked loose.
 

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Car: 2008 Tribeca, 2010 LGT, Sold: 2005 XT Limited
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Discussion Starter #5
I'll take a look, but i did it myself, and wasn't messing around near vacuum lines, just the front of the car.
 
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