sforshaw

I'm periodically experiencing strange behaviour from my 520d - at fairly slow speeds, possibly up to about 35mph, the car feels as though it's accelerating and decelerating in a mildly oscillating manner

The car's now done a little over 3000 miles - the problem was first noticeable at around 1500 miles. Initially I put it down to cheap diesel and immediatelystopped using supermarket filling stations etc, sticking to the likes of BP/Shell/Texaco. It has also been suggested that not keeping the tank topped up can cause problems due to condensation forming in cold conditions and the resultant moisture effecting the ability of the diesel to combust - I'm currently running at between a half and 3/4 tank and the problems has re-appeared. Also, whilst in this condition, the economy showing on the "swingometer" appears to drop of quite dramatically. On or off throttle makes little difference!

Substantially increasing the rpm and driving harder eleviates the problem, but I'm not happy that the problem's there at all

Anyone experienced anything similar, either with the e60 or other diesels?

KAF

Not really noticed that, I would suggest a dealer visit, maybe an ECU problem

pedrollo

Could it be the 'purging the particle filter' business, or a defect of it?

BetterMakeWay

LOL...who knows? But lets not start blaming all the purging of the particle filter.

mixterk

Funny you should say that....I felt something similar at about 40mph, I have a 535d. At the time I looked at the rev counter and it was hunting up and down slightly by about 300 rpm, also picked it up in the engine note...very strange
I put it down to the CIP rev being 20.01 its effecting my transmission. Getting a complete reprog again on the 6th hope it fettles it :'(

sforshaw

Yep, rev counter hunts also

browellm

Do you find it happens about mid-way through the warm-up period? If so it's the same thing I get.

It's always happened to me, but always disappears when the car is fully warmed up

sforshaw

When it last happened, I'd driven only a few miles. I'd used the car an hour previously for approx 4 miles, and 4 hours previous to that for approx 8 miles, so the engine would definately not be fully warm. However, my daily driving is very regular, but the problem is not! It's a couple of weeks since it last appeared.
After initially posting this thread yesterday evening, I did approx 6 miles again (a couple of hours after the last run - kids taxi!) and although there was definately no evidence of the issue initially, around a mile from home it reappeared, literally as if the engine had switched into a different programming mode, or as if something had failed/slipped/disconnected/reconnected etc

I've got nearer 100 miles to do this morning so I'll see what happens!

fantomas

I've also noticed some small variations of the RPM under 2000 RPM while the particule filter cleans itself.

sforshaw

How often does the filter clean itself?