TerpsRED

Does anyone else have an RPM's wiggle a bit at idle. ~50RPMs, just enough to see the needle move slightly? My idle is a bit rough when the A/C compressor is off. I've searched here and it seems that this is to be expected. Driver and empty passenger seats shake a bit which I think is to be expected.

This happens even when the engine is warm. The issue is less noticeable when the A/C compressor is running as this seems to boost the idle RPMs up a bit which smooths out the idle. There is no other noticeable shake any where else in the RPM range. Power is even and smooth all the way to redline.

I have an '06 C2.

Thoughts? Engine mount? Bad Plug? Just normal for a 997 itching to keep moving?

McCulla

05 C2 that I've had since 24K miles, now 33.5K. Mine sounds exactly like yours. I've read superficial stuff about motor mounts, but I don't have a clue. Mine's done this same thing since I got it. I've wondered about the vibration but have been too lazy to post an inquiry. Hopefully someone has an idea, but I can't help. Sorry.

cpbmd

I have the same subtle vibration at idle in my 07 997. I try to forget about it otw the car will drive me to the loony bin.

adg44

My 996.2 did this as well, and everyone said it was normal.

TerpsRED

does anyone know if you can adjust the idle speed manually? Or do you need a comluter module/communication device to adjust the idle speed up a bit. I'd love to find out that like the old days, there is a little idle screw to just turn it up a notch. That would solve the issue. I need like 50-100rpms to smooth out the idle.

TerpsRED

A new update to an old thread...I had my car in for some minor service and a last look over before my CPO ends. The tech noticed the vibration in the cabin that seemed more than just your normal vibration at idle. They determined that the engine mounts were indeed bad. They replaced them under warranty (just the two mounts in the engine bay) and the car now idles smooth as silk, with only the slightest hint of vibration that the engine is running.

gota911

Good for you that a) they found the cause, and b) Porsche paid for the repair!

Thanks for the follow up and report on the cause/resolution.

McCulla

TerpsRED, can you tell me approximately how long the shop took to do your mounts? I'm experiencing the same thing, the engine is checking out fine, so I want to just ask my tech to change the mounts, even if it's on my nickel.

TerpsRED

The bill showed .8 hours of labor to swap out the mounts. With the right equipment (Engine jack and lift), I hear the swap is a very easy job. The hardest one looks to be the passenger side one behind the airbox. I'd bet it took less than .8 hours with experienced guys, that was just the Porsche billing rate for the job.

utkinpol

in my car it is usually due to bad gas. my normal idle rpm usually fluctuates from 710 to 725 rpm.

McCulla

Thanks for the info TerpsRED. When I change my oil it takes about .8 hrs (waiting for drainage..) so this must be pretty quick for an experienced tech. On my list.

BHMav8r

Mine does the same thing - not so much when before the engine warms up because the idle is a little higher.

I brought it up at the 20K services and they were deer in the headlights. They suggested maybe new sparkplugs.

Sound worth looking into -also sounds like a pretty straight fwd DIY.

Neotorque

On cold days, mine (05 C2) will wobble slightly (maybe between 700-800 RPMs) at idle, usually at the first stoplight I get to (and almost always when the tiptronic defaults into first gear at startup, instead of second like usual). Nothing after that. I feel like that happened in my Lexus too. I haven't been too concerned with it since it goes away completely once engine temp clears the lowermost (100) marker, but let me know if it's time for me to panic.

TerpsRED

Sorry folks, I should have been more clear. I've edited the subject line in the thread. The RPM still bounces slightly, but the car no longer vibrates as it did when at an idle/standstill. I was never put off by the vibration, just thought it was part of the nature of this particular car. The car never had any shifting problems or was unstable in any way.

seskiyapan

My 05 C2S with 20k does the same thing and my passenger seat vibrates just as you say. My tech said the wiggly idle is normal and happens in most cars and they reported this to Porsche as well many times and did not get a solution for this.