Intermittent MPG needle / Vehicle exhibiting hesitation / Following turbo refurbishment

[Flexfer]

Greetings, everyone.

Attempt to maintain brevity. I lack mechanical aptitude and seek assistance prior to returning my vehicle to the shop. Any guidance would be welcomed.

Present owner of a 2015 320d F30. Possessed for six years.

Recently installed a refurbished turbo after a turbo failure. Comprehensive servicing was conducted once again. The vehicle was returned to the garage after a few days due to my suspicion of exhaust fumes infiltrating the cabin. The gasket between the diesel particulate filter and the turbocharger has failed. A new gasket and v-clamp have been installed. Appeared to have resolved the issue.

Recently, I have seen that my MPG gauge fluctuates significantly, dropping from 50 to as low as 15 MPG with little acceleration at both low and high RPMs. There seems to be pause, followed by the needle swiftly returning to the upper range, namely 50-60 mpg. It is certainly not operating as smoothly as it did when I originally had the vehicle back after the turbo replacement. Unhurried.

I have since purchased an OBD scanner, modest in nature, only to examine potential issues. No codes have been generated; nonetheless, I have been attracted to many numbers.

The airflow rate from the MAF sensor is inconsistent.

Example: 0.3 lb/min - 3.0 lb/min.

The equivalence ratio (lambda) mostly remains around 1.999, however some fluctuations may occur while driving.

The voltage of the oxygen sensor ranges from 0.5 to 1.0 volts.

I suspect my lambda sensor may be malfunctioning.

I have not had the DPF cleaned, however I have attempted forced regeneration and added Wynn's DPF cleaning to the fuel tank.

No emissions or irregular idling.

The vehicle had not shown any problems until the turbocharger malfunctioned a few weeks ago.

The vehicle has accumulated 95,000 kilometres.

Any guidance would be appreciated. I hope that some of this is comprehensible.

Salutations. 👍

Revise

The vehicle is scheduled for an EGR recall at BMW on January 10th.

[Black_raven]

The first consideration is that an element inside your intake system may not be properly seated or sealed, such as a twisted or broken rubber seal on one of the intake pipes that was disturbed during the procedure.

I anticipate that the garage will first verify their work to ensure everything is correctly assembled, and ideally, it will be a simple resolution.

[Flexfer]

Thank you for your response.

I inspected the engine compartment this morning for any apparent issues but found nothing. Disconnected the maf to inspect and clean it. Departing for a brief test drive before to visiting the garage tomorrow.

The vehicle has been taken to the shop twice after the turbo replacement to verify their work and to redo the gasket and clamp.

Attempting to formulate a preliminary hypothesis on the potential issue.

Enquiring about the accuracy of my OBD reader. Acquired only for code reading and preventive maintenance purposes. I may get the Carly OBD because to the several good evaluations I have seen.

[paulh2602601]

What is Bimmerlink? is superior than Carly and requires a single payment.
Additionally, BimmerCode requires a one-time payment for coding services.

[Flexfer]

I will examine them. 👍

The automobile will not be placed in the garage until January 6th. 😧

The cleaned MAF sensor seems to have provided a little reaction during acceleration. Occasionally remains somewhat reluctant.

I am preparing to run Wynns EGR cleaner via the intake once I determine the method.

It is quite plausible that the issue may be attributed to the EGR and its forthcoming recall. It is hoped that the EGR and cooler will be replaced.

Does anybody know the location of the lambda sensor on my model? 2015 BMW 320d F30?

Salutations. 👍

[DreamCatcher88]

The Lambda sensor is positioned above the DPF; I suspect that your problem is attributable to an inadequately configured turbo during its reconstruction, rather than the EGR cooler.

[Flexfer]

I suspected that could be the situation with Lambda. 👍

I really hope that is not the case for the turbo. The vehicle exhibited more responsiveness during the first weeks after the installation of the turbocharger. Except for a little leak at the gasket.

Operated the vehicle again this evening after the cleaning of the MAF sensor. Appears to have regained vitality. Abundant responsiveness on the freeway in fourth, fifth, and sixth gears. Consistently maintained rhythm.

Hesitation seems to manifest as operating in lower gears at speeds below 30 mph.

The OBD is connected, however the MAF air measurements remain inconsistent.

30-55 grammes per second on the freeway. 2500 RPM 0-17 g/sec at idle. However, exhibiting erratic movement.

The voltage of the O2 sensor seems to be within the acceptable range. 0.5 volts to 1.0 volts.

The lambda ratio is mostly 1.999 at maximum on the OBD.

Continue troubleshooting the situation tomorrow until a technician is available to examine it.

[Black_raven]

As paulh2602601 noted, it is quite peculiar after the turbo modifications.

[mrnobady]

Have swirl flaps ever been blanked?

[Flexfer]

Negative. Entirely standard, devoid of modifications or maps.