Technical Is it normal for a brand new car to vibrate/pulse when idle?

[Izzzy]

I bought a new Fiat 500 Dualogic a couple of weeks ago and have noticed that when the car is idle the car has this pulsing vibration which can be felt through the driver and passenger seat.

It only happens when the car is idle with the brakes applied or the parking brake applied (with the car in gear and when neutral).

I'm not sure whether to take it back to Fiat so they can check it or if this is normal as it's the first time I've had a semi-automatic?
Plus, I have a feeling that they will just say it's normal...

Any advice would be appreciated

 

[Piccolo Nero e Bella]

I bought a new Fiat 500 Dualogic a couple of weeks ago and have noticed that when the car is idle the car has this pulsing vibration which can be felt through the driver and passenger seat.

It only happens when the car is idle with the brakes applied or the parking brake applied (with the car in gear and when neutral).

I'm not sure whether to take it back to Fiat so they can check it or if this is normal as it's the first time I've had a semi-automatic?
Plus, I have a feeling that they will just say it's normal...

Any advice would be appreciated

Can't guess what it may be but it certainly doesn't sound normal. I'd be taking it back - and hoping it doesn't decide to behave itself while it's in their hands.

 

[KaZetec]

Sounds like the air con fan. They can be loud and vibrate. Can be made worse if it gets hit by stones.

 

[Maggie]

Don't be embarrassed to get the dealer to check it, that's why you bought new.

 

[John202020]

With the car fully warm, with the ac off,no electrical loads and in PARK it should idle smoothly.
Now try putting on the AC/climate control, is this the effect, if not turn the AC/climate control off, now try neutral(should be the same as park), then try drive, heavy loads like the ac+cooling fans/headlights/heated rear window whilst stationary can make the car vibrate some if turning everything off and putting in park stops this I would not worry, though you could ask your dealer to increase the idle speed a little say 100 RPM to lessen the effect, however this may not be possible in today's modern cars as it maybe ecu controlled/programmed.

 

[alexGS]

You've mentioned it's a Dualogic, but is the engine a TwinAir?

TwinAir is available with the Dualogic in some parts of the world. Having only two cylinders, it is inevitable that there will be pulsing effects at certain speeds (engine mounts are designed to damp out the pulses at most speeds), so what you're noticing could quite possibly be normal, regardless of it being a brand new car.

For those that are about to claim that the TwinAir is as smooth as any other, it's a four-stroke engine, so each cylinder develops a power stroke on one out of the four strokes... that's power for 25% of the time... (half a crank revolution out of every two revolutions). So with two cylinders, they are producing power 50% of the time. As with a three cylinder, that's less than the 100% possible with a four-cylinder, and so there must be more of a pulsing effect than with a four cylinder. Flywheel and balance shafts can reduce the effect but it would be impossible to completely fill in the missing power strokes.

-Alex

 

[John202020]

You can't beat a nice straight six for smoothness ?

 

[alexGS]

With the car fully warm, with the ac off,no electrical loads and in PARK it should idle smoothly.
Now try putting on the AC/climate control, is this the effect, if not turn the AC/climate control off, now try neutral(should be the same as park), then try drive, heavy loads like the ac+cooling fans/headlights/heated rear window whilst stationary can make the car vibrate some if turning everything off and putting in park stops this I would not worry, though you could ask your dealer to increase the idle speed a little say 100 RPM to lessen the effect, however this may not be possible in today's modern cars as it maybe ecu controlled/programmed.

I agree with your knowledge - inline six-cylinder is indeed the smoothest but be aware there is no Park or Drive with a Dualogic. Whether it's in N or 1, the idle is the same because the clutch is disengaged (as it would be for a manual) so the engine is unloaded.

You're also right when you say that the idle speed cannot be adjusted. It used to be a screw that jacked open the throttle plate... These days it is a "movable feast" - the engine ECU calculates a target idle speed based on prevailing conditions (including whether the car is moving), and then dials the ignition advance (or diesel injection timing) up and down to achieve this target. To a lesser extent, the motorised throttle is adjusted as well - and even on a diesel they have a motorised throttle now - bizarre. Of course it's always possible for something to go wrong; most often something simple, like an air leak into the induction system.

Before we can get any closer to an answer, I think we need to know what engine it is. FIAT do pair the 1.3 MultiJet diesel with the Dualogic for the Grande Punto, I assume not in the 500. Which leaves the four-cylinder 1.4, 1.2 or two-cylinder TwinAir as possibilities, and they all have different characteristics.

-Alex

 

[jrkitching]

Any advice would be appreciated

Go testdrive another car with the same engine & gearbox as your own. You're familiar with yours, so any difference should be immediately apparent. It's the best way of finding out if they really 'all do this, sir'.

You might want to go incognito to a different dealership.

You can't beat a nice straight six for smoothness

Does anyone else remember doing the thruppenny bit test when buying a used car? Wonder if we can do the same with the new £1 coin?

 

[Maggie]

Go testdrive another car with the same engine & gearbox as your own. You're familiar with yours, so any difference should be immediately apparent. It's the best way of finding out if they really 'all do this, sir'.

You might want to go incognito to a different dealership.

The simplest and best advice.