[joosttromp]

Hi all, thanks for having me on the forum!

About 6 months ago i bought a 2nd hand E90 LCI 10-2008 330xd N57 (245bhp/180kW/520Nm) manual 213k km on the clock, currently about 224k.

Just after I bought it, I noticed the idle rpm was bouncing a little and this developed over 2 months into a bouncing idle RPM between 650 and 800 rpm, the bouncing had a very stable frequency. If it got outside of this range, it usually just stopped bouncing and went back straight to 700 rpm.

When it was bouncing badly, it also did it when driving in 1st gear at idle rpm. If you'd then push the throttle a bit (too) much it would quite voilently accelerate and directly choke a few times in a row. This behaviour was only noticable when engine was warm. It also seemed to me that (full-)power delivery over the entire RPM range was sometimes slightly hesitant. Now since a month or so, this behaviour -seems- to have gone away, although not completely, rarely i see the rpm needle bounce only very slightly

But what is now very apparent is that if I engage the clutch from standstill and trying to drive away in 1st gear, the car shudders sometimes quite heavily. But only when engaging the clutch. When trying to drive away in 2nd gear, it's sometimes not even there, driving away in reverse seems is less shuddery than in 1st. Also this, is only observed when warm. When the engine is cold, it drives away from standstill just smooth.

Both of these behaviours, but especially the last one are really annoying me. I've been searching over the peroid of the last frw month but I've never found a topic that is similar (enough) to my symptoms.

Over the course of time, I've had the BMW software updated when I first brought it in for inspection after I bought it. Glow plugs and controller were not working, so replaced. I've had the EGR replaced by a bmw remanufactured one and the air inlet cleaned. Next to that also the aux belt and pulleys replaced and the air intake valve (helps to shut down engine smoothly). Also the car has been remapped by a guy who's been in the trade for over 2 decades, the remap did not have any effect on these issues, good or bad.

After reading as much as I could I can suspect injectors, high pressure fuel pump, flywheel and/or clutch. But I'm not looking to preventively replace everything.

I really hope somebody is able to help me or send me in the right direction finding the solution.
Thanks!!

[joosttromp]

It was the fuel control electronics unit on top of the high pressure fuel pump

[Andy198712]

Interesting! Was it giving a code for that too?