: Shake at idle



Stoopalini
10-17-08, 12:46 PM
I noticed something which seemed like a rough idle, as the car will periodically shake and shimmy when sitting still at an idle (not steadily, but comes and goes), but the tach stays completely stable. Along with this, came the horrible diesling sound at shutdown, so I took it in to the dealer for motor mounts.

I just got it back with new motor mounts installed, and the diesling at shutdown is gone, but the shake at idle remains. The tach is still very steady, so I don't think it's an ignition issue, or is the tach really that slow?

I asked the dealer to check the tranni mount, cradle and rear bushings and they said they were all fine. Is it normal for these cars to shake a bit at idle?

Oh, and I'm also getting a pop from the muffler during shifts, which I assume is related to the factory rich tune, but thought I would mention it in case it's related.

Thanks,
Thomas.

Jon
10-17-08, 12:52 PM
Yes. That's the first thing I noticed when I got the V. It shakes a bit at idle.

It's the 400 horses trying to get out ;)

Stoopalini
10-17-08, 12:59 PM
Does your shake come and go, or stay constant? I test drove an '07 before buying my '05, and the idle was very smooth, no shaking.

On my '05, it will be nice and smooth, then all of a sudden, the car shakes and feels like it's going to stall (but the tach stays steady), then the shake goes away and it's smooth again. Wait 15 seconds, and repeat ....

Thomas.

Jon
10-17-08, 01:09 PM
No.. Mine's constant. And it's very subtle. How bad is it shaking?

When it starts shaking is anything else happening? Is the fan on?

I'm having a similar problem with my Windstar right now. Whenever the fan turns on the engine shakes and sputters. One of my cylinders is actually misfiring. I've tracked the problem to the wires and ignition pack and replacing that. Sounds like yours may be similar? But my RPMs drop...

What happens if you rev the engine while it's shaking?

qqik4u
10-17-08, 01:09 PM
I would look at the motor mounts - see if they have any cracks as they are fairly soft for these cars.

Jon
10-17-08, 01:17 PM
I would look at the motor mounts - see if they have any cracks as they are fairly soft for these cars.
But he just got them replaced and the problem still exists...?

qqik4u
10-17-08, 01:19 PM
But he just got them replaced and the problem still exists...?

My Bad - should learn to read first before :canttalk: -

qqik4u
10-17-08, 01:26 PM
let's try this again after the read. If you replaced your MM you will still have a shake but not as much as a broken MM shake. Also I have had MM swaped 3 times until I went with the UUC MM. The have been holding up much better and I would recommend to all.

Your backfire has to be in the tune as with my config I have backfires during decellaration and I kind of like it as it scares the cats of the street. You could get it tuned to get the backfire away, but if it doesnot bother you then leave it - But make sure you do not have any cracks in the exhaust setup.

Shake, pop, rattle, growl all part of muscle car setup I say :thumbsup:

Stoopalini
10-17-08, 01:39 PM
How bad is it shaking?

Enough to make my wife go "why is it doing that?" LOL!! It's definitely more than a normal V8 idle (I've been a muscle car guy for a long time now)


When it starts shaking is anything else happening? Is the fan on?

Good question! Not sure, I'll have to check that out.


What happens if you rev the engine while it's shaking?
When reving the engine, everything seems to be normal, and the car pulls great. That, including the tach staying steady, is what leads me to believe it's not ignition related, and really has to be a mount?


Your backfire has to be in the tune as with my config I have backfires during decellaration and I kind of like it as it scares the cats of the street. You could get it tuned to get the backfire away, but if it doesnot bother you then leave it
I assume the popping is due to raw fuel making it through the exhaust, which would be a sympton of a rich tune. I'll eventually get a mail order tune and hopefully it will have a leaner mix and more aggressive timing curve (for increased power) which should eliminate the popping as well.

Thomas.

Jon
10-17-08, 01:49 PM
When reving the engine, everything seems to be normal, and the car pulls great. That, including the tach staying steady, is what leads me to believe it's not ignition related, and really has to be a mount?


If it's a mount shouldn't the vibration be amplified when you're revving it?

Try and notice if there's anything else going on when the shaking happens. Took me a while to notice my fan was kicking in on the Windstar when the engine was shaking.

lollygagger8
10-17-08, 01:52 PM
UUC MM's took the shake rattle and roll :elvis2: out of the V for me! Even with new OEM mounts, the engine shakes a lil still.

If you want the "pop" out of the exhaust, the tuner can fix that. All they do is add more fuel on decel.

Ferny
10-17-08, 02:43 PM
my 04 does the same thing. its been in the shop once before. i think they replaced one mount. but its doing it again. ima have to take it in soon before my warranty expires. damn motor mounts :banghead:

CTS-Voodoo
10-17-08, 03:37 PM
I had the mounts replaced before I bought mine (had 27k on it) and despite my mounts being brand new the car shakes about every 15 seconds like you said. I asked the dealership about it and they said to get used to it..

Natedog
10-17-08, 03:42 PM
shake @ idle = stock cam... while not aggressive, its still enough to 'shake' the car... be lucky to be endowed with such a big engine

lollygagger8
10-17-08, 04:13 PM
shake @ idle = stock cam... while not aggressive, its still enough to 'shake' the car... be lucky to be endowed with such a big engine


I feel lucky to be endowed with such a big :gungrin:

tgeddings
10-17-08, 08:23 PM
I'm certainly no expert but did come across this at cadillacfaq

"Subject: CTS-V Unique Features Not Common with Other Cadillac Vehicles
Message #: CAS20040022
Corporate Bulletin Number 04-00-89-027 is currently available in SI.

Models: 20042005 Cadillac CTS-V
Rough Idle

The 400?horsepower LS6 V8 engine derives its awesome power through a combination of displacement, stroke and tuning. A key element of this combination is giving the engine better "breathing" ability through unique camshaft to valve lift and duration. The efficient process of getting the air/fuel mixture in and exhaust gases out of the combustion chamber is achieved through this higher valve lift and longer valve open times. The result of camshaft design results in what is commonly referred to as an unstable idle or the random roughness of the engine. This is normal and does not indicate a concern. "

It convinced me that my idle shake was normal, but I always knew I had a big cam..

CadzillaTN
10-17-08, 09:16 PM
idle shake is normal. However, the diesel truck shutdown is complete :bsflag:
I had all mounts replaced under warranty and it is still an issue. I was told when I bought mine to get used to it by someone here... I thought, nah, has to be fixable..

get used to it.

CTSV_510
10-17-08, 09:57 PM
shake @ idle = stock cam... while not aggressive, its still enough to 'shake' the car... be lucky to be endowed with such a big engine

:yeah:

I have relatively new motor mounts ~ 6 months old now. I odn't get much of a dieseling at shutoff, but sitting at idle I get some shakes. I like it, it's one more piece that makes the V the beast that it is!

Plus, I think that the LS6 cam is a little more aggressive in this respect than the LS2 cam. That's where you can see the difference between a real engine and one they'll just throw in any 'ol truck. :stirpot:

Stoopalini
10-18-08, 02:29 AM
Thanks guys, exactly the info I was looking for. I guess I'll attribute it to cam surge and not worry about it.

Thomas.

50 4Ever
10-18-08, 02:56 AM
Does your shake come and go, or stay constant? I test drove an '07 before buying my '05, and the idle was very smooth, no shaking.

On my '05, it will be nice and smooth, then all of a sudden, the car shakes and feels like it's going to stall (but the tach stays steady), then the shake goes away and it's smooth again. Wait 15 seconds, and repeat ....

Thomas.

The one major difference between the LS6 in the '05 and the LS2 in the '07 is the cam. The cam in the LS6 is more agressive which causes the shakes. The cam in the LS2 is not agressive, that is why it is "smoother".

:thumbsup:

buf05CTSV
10-18-08, 07:22 PM
Mine shakes periodically at idle. The LS engines do this because they have a cylinder shutoff to save gas. It's completely normal, and quite frankly, I love it. It's ready to rock.. that's all that means.

CTSV_510
10-18-08, 09:02 PM
The LS engines do this because they have a cylinder shutoff to save gas.

:umno:

whisler151
10-18-08, 09:08 PM
:umno:

Awesome smiley. I've never seen that before. Good sh*t!

tophat02
10-19-08, 01:23 AM
I've noticed mine shakes a bit more after the w4m tune. I just assumed he lowered the idle RPM. I don't really mind it, but I've got a couple of loose trim pieces in the car (including a broken shitty center console) and the rattling gets to me sometimes.

also, I've noticed that, when I'm at idle, I have to rev it a bit to see anything clearly in the rearview mirror! :rofl:

ctsv154
10-19-08, 03:32 AM
If you like the shake of the stock cam, you'll like the shake of this cam! 239/242, .649"/.609" 111 LSA

I get a lot of weird looks.