[Cm757]

Really at my wits end here.

Pre lci e91 335d.

I have a lack of power, a weird torque curve and awful mpg. Car is extremely slow down low, no meaningful boost until 2300 rpm. There is some boost, but less than 50% of its setpoint. After 2300, it consistently meets it's boost target until redline.

I have replaced:

Hpfp, lpfp, rail pressure sensor, regulator, and 6 injectors, fuel filter. All OEM parts.

Maf, map, charge temp sensor, every pressure converter and eucv controlling compressor bypass, every boost pipe including red one with new seals.

Dpf, egr are deleted.

I have changed every single vacuum line, everything is plumbed correctly and to their correct place. I've blanked off swirl flaps, egr and motor mounts at the vac manifold. There are no leaks whatsoever. We don't have the carbon buildup on our eu models, but intake mani is clean as a whistle regardless.

I have tested turbine control valve, compressor bypass and wastegate. All can be controlled normally, and seen moving when vacuum is applied. Turbine control valve has been correctly set with vac, but I have tried it in several positions.

Rail pressure is fine, within a few percent of target at all times.

Turbos were replaced by BMW in 2022. I have inspected both of them, both are sound with no play or damage to turbine or compressor.

Glow plugs are sound, and all 6 cylinders have been compression tested and within 5% of each other. Gearbox is sound and has been serviced. Car has been smoke and pressure tested, there are no boost leaks.

I have had it running several maps by several people including full stock, and they all have the same issues.

Does anyone have any ideas here? Ive tried literally every single thing I can think of and I'm getting nowhere.

[richard_tricky]

Could this possibly be the vacuum pump itself? Have you done a vacuum check to see how much it’s pulling?

The only other thing I can think of is the ecu is broken. Youve replaced so many parts and still have no solution

Have you sent the ecu for testing?

[diesel.e90]

Check the amount of threads that are on your turbo changeover, especially if you have had your turbos replaced. Should be about 16 to 17 threads after the nut if it’s less than that tighten it up some more and try that, should be a night and day difference.

[diesel.e90]

I was in the some boat as you tried everything nothing changed until I moved a bolt a couple of threads and it changed the car entirely