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Discussion Starter #1
My 2008 9-5 with A/T continues to provide power to the drive line when at idle, Enough so that it will propel the car uphill without giving it any gas. It also puts a scare in you when you take your foot off the gas but the car continues to accelerate. Idle shows about 950 RPM on the tach. Anyone have any ideas what would cause this?
 

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Some forward or reverse creep with foot off brake is normal. Idle speed may be a little high, probably was reset to reduce vibration in cabin. Need Tech 2 to change idle speed.

Does engine run smooth at idle? Could also have slight vacuum leak.
 

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What is the idle speed if you put it in neutral?

Note, it's going to idle at a higher RPM when it's cold, but the idle should drop to its normal speed when it's past the blue area of the temp gauge.

If the idle speed has been set higher via Tech II, that can be reset simply by disconnecting the battery.
 

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Discussion Starter #4
This is definitely stronger than normal idle creep. It was even more noticeable with icy roads. It requires active/aggressive braking to counter the force. Idle is just under 1000 rpm. It feels like you are revving up a bit in terms of the power being transferred to the drive shaft but there is no revving. Similarly, when driving on a road and I take my foot off the accelerator instead of coasting it accelerates and I have to brake to hold a certain speed. Obviously the torque converter is not spinning fast enough to transfer the power via centrifugal force if things were working correctly. One Saab mechanic suggested it might be a stuck solenoid in the A/T valve body. I was thinking that torque converters functioned exactly the same regardless of what gear the car is in but he said torque converters receive different amounts (flow volume?) of oil at different times as controlled by the computer via the valve body and perhaps something is amiss with that system. Anyone have in depth knowledge of these transmissions? Thanks
 

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Maybe the torque converter lockup clutch is not disengaging fully.

If this is the case, the T7 system is opening the throttle to keep up the engine RPM to what it wants. Do you have access to a Tech II or a good ODB II reader that can give throttle and airflow readings? If so, check what they are when the car is in neutral, and what they are when it is in gear.
 

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Steve already said this, I think, but the Tech 2 allows you to adjust the idle speed in D up to around 950 RPMs. This is usually done to address idle vibration concerns. Perhaps someone did this on your car? In mine, I noticed that it felt like I was fighting the car a bit in D by having to aggressively apply the pedal. Get yourself a Tech 2 (or get to somewhere that does) and see if that setting was tweaked. I ended up resetting mine to the default setting as I didn't like how much the car crept when I let my foot off the gas.
 

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Discussion Starter #7
Thank you for your input. I have a friend with a Tech II and will see when he has some time to hook me up.
 

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It's bizarre. My 07 9-5 Aero does that too when in drive. The vibration is so bad at red lights I just throw it in neutral. Ill talk to my mechanic about the tech 2 to see if its a setting he can investigate.
 

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There is idle adjustment when car is in D.
 

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There is idle adjustment when car is in D.
Yes, but my understanding is that it gets reset to factory if you disconnect the battery. Which is what I suggested way up in the thread. No indication if that was done. :rolleyes:
 

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My 2007 shouldnt need the adjustment. Idle speed is already 900 rpm.
Maybe subframe bushings, especially rear ones, or engine mounts are worn.
 
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