steering wheel movement causes slight rpm drop?

**Aetos** · 08-04-2008, 09:00 PM

Tonight while going out I noticed if I'm sitting at idle and turn my steering wheel in any direction a bit my RPMs will drop by like 100-200.

Car is 99 M6 with 45k miles. What could be causing this erratic rpm behavior?

**JoshieDoom** · 08-05-2008, 02:23 AM

Mine does it.. Power steering pump = parasitic drain...

normal i do believe....

**mark21742** · 08-05-2008, 02:33 AM

dont know if it does it quiet that much but my goat does it too, Josiedoom has it right

**JoshieDoom** · 08-05-2008, 11:15 AM

Mine does it when its at hot idle. Cold idle it just changes the sound of the exhaust like its putting drag on the engine.

**Firebirdjones** · 08-05-2008, 01:01 PM

Ya,,,years ago even on some carbed cars there was a power steering switch that would kick idle up when the pressure rised on the power steering pump,,,,don't know why GM got away from that but my guess would be gas consumption and meeting certain requirements. Every little bit helps I guess.

**Frost** · 08-05-2008, 01:51 PM

Originally Posted by Firebirdjones

Ya,,,years ago even on some carbed cars there was a power steering switch that would kick idle up when the pressure rised on the power steering pump,,,,don't know why GM got away from that but my guess would be gas consumption and meeting certain requirements. Every little bit helps I guess.

They do it in the PCM now, just like the A/C (which used to have the throttle bump noid too).

It's in the tq mngmnt section (engine not trans!) and it plays into the frictional loss model. The IAC does step a bit to augment it, but I believe that it's a static offset at idle, which is why you see the droop.

**Aetos** · 08-05-2008, 02:50 PM

Thank god, I thought I found another problem with my car

on a side note my 02 sensors just arrived, yay.

**Firebirdjones** · 08-05-2008, 04:28 PM

Originally Posted by Frost

They do it in the PCM now, just like the A/C (which used to have the throttle bump noid too).

It's in the tq mngmnt section (engine not trans!) and it plays into the frictional loss model. The IAC does step a bit to augment it, but I believe that it's a static offset at idle, which is why you see the droop.

Thats good to know. I noticed it was in the tune for the A/C but didn't realize or see anything for the power steering.