What would cause a shudder/tremble when idling?

[surfercalavera]

My 04 XC70 shudders/tremble when I am waiting at a stop light! I come to a stop and sit there for 10-20 seconds not feeling a thing when all the sudden it shudders. It does it from time to time though; transmission shifts smoothly and engine is sound once I press the gas.

Is this a transmission issue or engine issue? I know it could be a number of things, but I am looking for a place to start.

People have told me the following possibilities:

- Transmission idle valve
- Engine mounts are worn out
- Inspect timing belt or serpentine belt and check for loose components
- A loose vacuum hose


What is your take?

Thanks!

[guyeye]

AC engaging/disengaging?
Does it only happen momentarily when it happens? Do the RPMs dip?
I've heard the MAF might have something to do with this.

[JRL]

ALL three (3) motor mounts need to be new and then see if it does this.
Some of these do vibrate a bit, but for it to come one suddenly is a bit odd.
As was said, does the compressor engage when it's doing this?
Turn off the AC blower and does it do it then?
The quick RPM drop when the compressor comes on plus worn mounts could be the issue

[PierreC]

I would check the coils - chances are one of the coils is beginning to die.

[surfercalavera]

AC engaging/disengaging?
Does it only happen momentarily when it happens? Do the RPMs dip?
I've heard the MAF might have something to do with this.

AC works and it does not seem to make a difference, it shudders with or without the AC on.
It shudders for about 1 second, and the RPM does dip slightly, but has never gone out on me, but it is enough for me to notice.

Thanks!

[acools]

Surfer,

I have an 04 XC70 and had a similar problem.

Most people would not notice, but the driver (me) does and the RPM needle would barely move.

I fixed it by cleaning the throttle body carefully, when I replaced my PCV system.

I would check your motor mounts as well, along with vacuum hoses and my coils.

If it isn't constantly shuddering, only occasionally and it is sometimes hard to tell, I would bet on the TB.

[surfercalavera]

AC engaging/disengaging?
Does it only happen momentarily when it happens? Do the RPMs dip?
I've heard the MAF might have something to do with this.

AC works and it does not seem to make a difference, it shudders with or without the AC on.
It shudders for about 1 second, and the RPM does dip slightly, but has never gone out on me, but it is enough for me to notice.

Thanks!

[guyeye]

Reason I asked was because mine does this as well. It's fairly easy to ignore, but it'd be nice to fix. My ETM is so clean you could eat off of it. It happens when the AC is off. The coil idea is interesting, though it's never showed up on a Vida scan. I'd hate to go throwing parts at something so minor. How would one check the coils other than reading a misfire code with the Vida/Dice?

[shammyh]

Hmmm....

I have a 2004 XC70 (~79,000 miles), and also notice this exact same symptom.

It seemed to happen a bit more frequently during the summer months, and I haven't noticed it nearly as often since my last major service (details listed below).

It's also interesting I seem to be having identical symptoms despite my car being a bit of a baby in Volvo years. Maybe that can help isolate the issue?

As to the exact symptoms:

- Happens when the engine is fully at operating temperature
- Happens when at a stoplight only. Don't notice it at start while in the garage, or while moving.
- Definitely notice the RPMs drop for maybe half a second
- Feels almost like a bit of a lurch... normally it's barely noticeable (except to a anal-attentive driver), but very occasionally it'll be quite pronounced

As to my car:

- Entire PCV system replaced at 74K (dealer done via aftermarket warranty)
- Engine oil flush/clean, cam seals replaced, ETM cleaned, new timing belt kit at 74K
- Volvo dealer 75K recommended maintenance done at 73K
- Tranny is in good shape, no codes in VIDA/DiCE, no obvious leaks or hose problems
- Engine runs great all the way up and down the rev band. Holds maximum boost correctly too. AOC/Haldex in perfect working condition.
- Only run Mobil 1 since PCV replacement, change oil at 4500-5000 mile intervals

~~~~~~~~~~~

Would really love to get a handle on this... I've considered the MAF, the coils, or possibly even the CVVT timing system. And obviously I could do the coils or the MAF myself, but I'd rather not throw money at a problem without narrowing it down first. I do find it a bit suspicious it only happens at idle, and while stopped, which is prime time for the intake/exhaust variable timing to be mucking around trying to save fuel and/or the environment. My dealer is pretty bad at fixing these kind of issues (if it's dead, they'll fix it, but little stuff they always ignore), so I'm not sure where to turn next...

Any advice would be much appreciated!

[sjonnie]

My 04 XC70 shudders/tremble when I am waiting at a stop light!

My '02 has done that since I bought it in 2009. I've replaced everything on the engine suggested above except the coils. No change.