Odd shudder

**fat controller** · 28-09-2010,07:52 PM

This afternoon when starting my car to come home from work, the car shuddered for a few seconds before settling to a normal idle - the whole car was shaking, as though the engine was running rough, although it sounded fine.

Anything to be concerned about, or to check?

Also, and probably completely unrelated, since then the fuel consumption has improved - I was getting high forties in London rush hour traffic this evening - even after being in nose to tail traffic for a while, it was still showing 43mpg when we arrived home.

**tommyweaves** · 28-09-2010,11:54 PM

Mine's done that from time to time. I tend to put it down to cooler weather and me needing to give the glow plugs a proper chance to do their job; also my research on here has led me to believe it could be my DMF on the way out, but I reckon that's been on the way out for the past 60k miles, so I've stop worrying about it!

Sometimes I've had a lumpy idle when sitting in traffic, no rhyme or reason to it and the car carries on just fine month after month, so unless it gets worse and becomes more of a problem I'd not fret too much!

DSG4ME · 29-09-2010,01:34 AM

Do you mean it seems like the engine is falling out as you push the key to start it, and once running it's fine?

Both my PD's have done it from time to time, it could be a mount, if the VW ones are the same as Skoda's they will leak a red dye near the mount if they are shot, other than that don't worry, I've noticed my misfire has gone as well, this has to be air density causing it.

**fat controller** · 29-09-2010,04:01 PM

It wasn't as it was turning over to start, but immediately after the engine had started. It only lasted a few seconds before settling down to its normal idle. Maybe I didn't give the glowplugs long enough to do their job - wouldn't be like me, but entirely possible.

I think you could be onto something with the air density though - I've had a few cars over the years that would run better or worse depending on the weather etc. My Sierra was a particularly moody bugger, never awful, but on a nice cool, clear night would run like a dream. I am fast coming to the conclusion that the Passat is another moody car - yesterday it was running really well - smooth, quiet, good consumption etc, yet today its running like a box of bolts, and the consumption is worse by 7 to 10 mpg on the same journey as yesterday.

Cars - definitely female.

**rapport25** · 29-09-2010,04:04 PM

Originally Posted by fat controller

It wasn't as it was turning over to start, but immediately after the engine had started. It only lasted a few seconds before settling down to its normal idle. Maybe I didn't give the glowplugs long enough to do their job - wouldn't be like me, but entirely possible.

I think you could be onto something with the air density though - I've had a few cars over the years that would run better or worse depending on the weather etc. My Sierra was a particularly moody bugger, never awful, but on a nice cool, clear night would run like a dream. I am fast coming to the conclusion that the Passat is another moody car - yesterday it was running really well - smooth, quiet, good consumption etc, yet today its running like a box of bolts, and the consumption is worse by 7 to 10 mpg on the same journey as yesterday.

Cars - definitely female.

Yes i think you could be right

. The thing with the fuel consumption is the crap weather heater on lights etc... that will knock your mpg. As for running like a box of bolts. Not had that one yet

**fat controller** · 29-09-2010,04:12 PM

Originally Posted by rapport25

Yes i think you could be right

. The thing with the fuel consumption is the crap weather heater on lights etc... that will knock your mpg. As for running like a box of bolts. Not had that one yet

Its hard to describe what I mean by that - not doing anything of note, but just not running 'right'.

I do worry sometimes that I seem to have a bit of sensitivity to vehicles and how they are running, yet I have only very limited mechanical knowledge to work from. I am known at work as one of the people that can take a vehicle out and decide if it is right or not, and the engineers tend to use me sometimes to get an honest description of a fault.

The downside of that is that I worry about my own vehicles little 'off-days' (not helped by reading about faults on forums

)

**Stuart W** · 30-09-2010,01:01 AM

Can't say I've ever noticed any difference in the way mine runs, whether the engine is cold/hot or whatever the weather is outside.

The only thing was that last winter when the car was cold, when moving off the clutch would tend to bite suddenly rather than engage progressively, and that might have been down to wear and/or the cold winter, so I await this year's cold weather with interest (or perhaps trepidation!).

Also, I sometimes hear a bit of noise at idle, which is presuably clutch-related because it disappears/changes when I depress the pedal, but since it's not too intrusive I've just ignored it, on the assumption that if it's normal wear and/or the DMF then I'll get a bit more noise as a warning before it's about to go.

The only other thing is a very occassional random shudder/rough idle, but I haven't really noticed that so much as the car has reached the higher mileages.

Oh, and it rattles a bit for a second or two after starting from stone cold, but so have all the other high mileage cars I've owned

**molgrips** · 04-10-2010,02:04 PM

I am fast coming to the conclusion that the Passat is another moody car - yesterday it was running really well - smooth, quiet, good consumption etc, yet today its running like a box of bolts, and the consumption is worse by 7 to 10 mpg on the same journey as yesterday.

7-10mpg? You definitely have a problem.

Heater, lights etc make a very slight difference to mpg. What makes far more of a difference is the weather - colder weather makes it worse (although not sure why on a diesel); rain on the roads also makes a big difference; wind obviously; and winter diesel between Nov-April ish has a lower cetane rating so also makes a difference.

However all those things would only reduce your mpg by 5 at most. To lose 10mpg from one day to another is drastic. There is something wrong with your car - do you have a flat tyre?

Also mine's perfectly consistent whatever the weather or temperature. YOUR car is moody, they shouldn't be.

**fat controller** · 04-10-2010,07:00 PM

Tyres all good, molgrips, and apart from a misfire (see other thread) the other day, its been fine since - even consumption seems settled at the moment.

**PeteK** · 04-10-2010,08:49 PM

I don't think i've ever owned a car that feels like it drives the same every day. Some times my car feels ultra smooth (including the engine, ride, steering & transmission), other times it just feels slightly courser in the way it drives although it still runs well. I think it may be influenced by the mood of the driver! I always find it runs especially well on early morning starts - I know this is caused by the cold denser air with regards to the engine but i'm not sure how it can effect the suspension as the ride always seems smoother.