A funny thing happened on the way to the motorway.  After having already been driving for 20 minutes without issue (and indeed, in this car, for six years...) I reached the end of the M49 from Bristol -braking to a stop of course - and the roundabout that leads onto the M4 westbound, and on pulling onto the slip road by the new Severn Bridge, the car randomly started trembling (best way to describe it).  It was very slightly jumpy, you know.  It was the same in all gears and speeds.

 

It still went without being noticeably underpowered, but obviously you wouldn't want to drive to Edinburgh or similar feeling like you were in a suspension free medieval waggon.

 

I pulled onto the hard shoulder, lovely view, and restarted the engine - and the problem was gone.   Hasn't been back, either, despite driving again in various conditions and speeds.

 

This isn't a car that doesn't have its odd moments - some of which are documented on this site, which are seen once to never be seen again.

 

If anyone thinks it might be at all related, I also have an open thread for an intermittent ABS light.  

Wonder if anyone ever looked at this?

 

Didn't happen for two months then did again today... as before, after slowing for, and then leaving, a roundabout.    Restarting the engine once again cleared it.

Possibly a failing coil pack?

35 minutes ago, Me-109 said:

Possibly a failing coil pack?

Thanks!  I agree it seems like it would be more likely electrical than mechanical, as otherwise restarting the engine would not clear it.

 

Looking at failing coil pack symptoms, I have not got any others other than this vibrating (eg no issues starting, no loss of power, fuel economy fine).

 

However this did make me check a scan I had a couple of months ago with another issue (failing ABS pump, now replaced and fine) and there is this on there which I confess I just didn't look at at the time as the problem went away:

 

2.p0672 cylinder 2 glow plug circuit

 

Could that be related?

Ah, diesel! Wouldn't have expected a glow plug issue to materialise once you'd been running the engine a while as you say, but it might point to an injector going bad. Not sure if they store codes for bad operation or if you have to catch it at the time.

11 minutes ago, Me-109 said:

Ah, diesel! Wouldn't have expected a glow plug issue to materialise once you'd been running the engine a while as you say, but it might point to an injector going bad. Not sure if they store codes for bad operation or if you have to catch it at the time.

Nor me, but a bit of Googling (no substitute for experience and a mechanic of course, but at a first glance...) does throw up "The engine may misfire due to the colder-than-normal cylinder head temperature. The engine may hesitate during acceleration".

 

Which could be what I'm getting, somewhat, if I squint...

 

The car has been serviced and all codes reset since this scan (May) and the problem hadn't recurred since then and until Monday (took the car out yesterday with no issues) so perhaps something new will appear on the scan I've got booked in tomorrow.  Will update!

My BKD goes a bit lumpy sometimes, I usually notice it when slowing down on the motorway if there's some congestion.

 

I do also have a glow plug fault on the scan, but as the engine is up to temperature I doubt it's anything to do with that.  I've just been ignoring it lol

Well the issue was...

 

 

 

...drumroll...

 

 

... dirty fuel injectors.  Cleaned up and it's made quite a difference, even to "normal" driving, which hadn't been normal before but evidently I had got used to it.

Interesting! How did you clean them?

 

I've checked the values on mine in VCDS at idle and they seem ok, but never seen the values when the lumpiness occurs!

1 hour ago, chrisund123 said:

Interesting! How did you clean them?

 

I've checked the values on mine in VCDS at idle and they seem ok, but never seen the values when the lumpiness occurs!

Just a sponge and washing up liquid.

1 hour ago, JamieH86 said:

Just a sponge and washing up liquid.

 

WHAT!!??

9 hours ago, JamieH86 said:

Just a sponge and washing up liquid.

That's... Not usual 🤯

Well not really...happy to say!

 

I have no idea how it was cleaned, the mechanic did it. 

On 10/07/2024 at 09:31, JamieH86 said:

Googling (no substitute for experience and a mechanic of course, but at a first glance...) does throw up "The engine may misfire due to the colder-than-normal cylinder head temperature

 

Google does not have a BS filter.

16 hours ago, JamieH86 said:

Well not really...happy to say!

 

I have no idea how it was cleaned, the mechanic did it. 

 

My approach to cleaning injectors and turbos is to use a tank of premium diesel and go on a motorway drive and hold the revs between 3-3.5k for about 10-15 miles so it gets nice and hot to burn away deposits.

1 hour ago, Golf-Fiend said:

 

My approach to cleaning injectors and turbos is to use a tank of premium diesel and go on a motorway drive and hold the revs between 3-3.5k for about 10-15 miles so it gets nice and hot to burn away deposits.

Yes I will do an Italian tune-up (as I believe it's called) as well.