Massage seats?

[polar]

Hello!

I think my ZMC is developing a new feature!?!

When coasting along at a steady pace I can feel a faint, soft bouncing movement in the whole car.
It bounce at 3-4 b/sek, its constant and only occurs at 2100-2300 rpm.

When slowing down or giving gas it disapears.
I've had the wheels off and nothing seems off and the weights is still there.
The engine make no signs of missfire and there's no EML.
There's no noice coming with it, as I can hear.
What's going on? It's super annoying but also a little bit nice

As a side note, the car wants a few more cranks than before to start. The battery is 1,5 yers old and always hooked up to a CTEK.

Can it be the shocks? I've had the OE+Eibach combo since two years.
Can it be the early stages of a failing CPS or TPS?

What do You think? Make suggestions!

[Huz-Z]

The graphic is appropriate, that's for sure.

That sounds like some odd sort of resonance issue. Maybe something, like a shock or motor mount, isn't as stiff as it should be; perhaps you should check those. I wonder if this could be caused by incorrect tire pressure as well? Probably not, but it couldn't hurt to check.

But if you like the feeling, get a cowboy hat and pretend you're riding a horse.

[chickdr]

I have this issue at times. Often when starting up after a while(weeks) it will be very rough as I drive. Most of then time when I go somewhere and shut off then come back home, the vibration is gone. Very strange. I wondered about motor mounts too.

[racerbruce]

Originally Posted by chickdr

I have this issue at times. Often when starting up after a while(weeks) it will be very rough as I drive. Most of then time when I go somewhere and shut off then come back home, the vibration is gone. Very strange. I wondered about motor mounts too.

I've noted "square tires" when my Red Roadster sits for a week or two....the minor vibration clears after 3-4 miles.

[polar]

There is some mods to take into consideration:
Vibra Technics street motor mounts (2 years/3200 miles)
Rogue transmission mounts (2 years/3200 miles)
Eibach springs with all new rubber pads (1,5 years/1800 miles)
Apex 18" Arc-8 (1,5 years/1800 miles)
Michelin Cup2 (1,5 years/1800 miles)

If the mounts fail, especially the VT's, I think it would be more of a vibration and rattles. (?)
I have tried to change the tire pressure, did not help.
Tires could be the cause, flat spots and so on, my car also sits for weeks.

If its a failing sensor, could it cause this type of bounce?
Can it be vanos related, i.e. leaking coil pack seals? Cams not rotated right...
The reason to my suspicion is the rev range in witch it occurs.

There seems to be a smilie for every occasion! Now its friday so...

[chickdr]

Originally Posted by racerbruce

I've noted "square tires" when my Red Roadster sits for a week or two....the minor vibration clears after 3-4 miles.

I have the flat spot tire issue too, but it isn't the same. The tires are felt through the steering wheel while the vibration he speaks of is from the center of the car(drive line). One board member postulated it is from the UUC transmission mounts I have, but it didn't start immediately after putting them in (well over 5yrs ago). This vibration started a couple of years ago. I guess the material in the UUC mounts could be stiffening up?