Steve J

Hi, I'm hoping someone can jump up with a known issue / solution to this one.

Car is an E60 535d which is having the following symptoms.

Travelling on a motorway at constant revs (say 1700) every few seconds the revs drop by 300 with the consequent engine labouring for a second or so then bounce back to normal. Keeps doing that until you either take your foot off the accelerator or push the accelerator down. Sort of like when it's burning soot from the DPF but it's doing it most of the time when just cruising along.

Also, when putting the car under light load (going up a hill, or not aggressively accelerating off from stationery) you can feel the drive train judder (like a worn clutch).

Independent specialist diagnostics has picked up nothing.
Drive shaft and donuts are ok.
Thought it was an injector which was going slowly out of phase, but no change when they swapped.
Gearbox fluid level fine.

Any simple things I can check / clean which could be the cause and I can eliminate?
They are now saying it could be gearbox but no codes are coming up showing a problem, so can't guarantee that a £3k rebuild will resolve.

It's got 150k on the clock.

Please tell me it's a simple and cheap fix as I love this car and would rather keep it for another 150k miles.

Cheers

bmwrider2010

Sounds like torque converter fault

Steve J

Thanks. Local specialist don't know what the cause is but a couple of posts on here seem to have similar symptoms relating to mechatronic system and transmission fluid changes.
Don't think it's worth fixing though so may chop in.