Diagnostický případ

Jen diagnostikované vozidlo

Libor Fleischhans

Jazyk případu:

Misfire during warm idle

11.02.2025 | aktualizováno 11.02.2025 12:11:34 0 58x

Informace o vozidle

VIN:	WBAPH31030E295117
Výrobce:	BMW
Model:	3 Series
Rok výroby:	2010
Kód motoru:	3,0 325i
Typ motoru:	N53 B30A
Výkon (kW):	160 kW
Převodovka:	Manuální
Palivo:	Benzín
Najeto:	186 458 km

Jak se závada projevuje

Nefunguje / funguje nesprávně. Misfire only at warm idle.

Jak často se závada projevuje

Trvale přítomná závada.

V jakém systému se závada vyskytuje

Motoru.

neukládá žádný chybový kód

Doposud provedeno bez úspěchu

1) New NOx sensor (fault memory recording)
2) New fuel injectors, but not OEM
3) New spark plugs
4) New ignition coils
5) Intake manifold cleaned
Further cost estimate by BMW dealer is almost 5 000 €

Závěr

VOZIDLO JSEM NEOPRAVOVAL, PROVÁDĚL JSEM DIAGNOSTICKÉ PRÁCE

Für unseren Partner nur die Diagnose mit FCD-Logger gemacht.

### Conclusions:
The FCD logger algorithms detected issues with the dynamic change in the sum of Short + Long Term Air/Fuel Trim (total mixture adaptives). This means that mixture adaptation dynamically changes over time based on two parameters:

1) Engine oil temperature parameter
2) Transition from additive to multiplicative adaptives

The LOG recording also shows that the cylinder bank 1 adapts to the operating warm state to –50% (maximum lean condition), while the second bank adapts only to about half the value (–20% lean).

Since the crankcase ventilation output is close to the first three cylinders, this could indicate that the engine has fuel vapors in the oil pan. Gas measurement in the crankcase system confirmed this with readings of **270 ppm HC (cold)** and **2900 ppm HC (warm)** (normal values: cold **0 ppm**, warm **~20 ppm**).

The fuel source could be a **leaking high-pressure fuel pump**.
FCD-Cloud algorithms estimate a **95% probability** that the high-pressure fuel pump is defective based on multiple indicators!

Additionally, the LOG graph indicated a **non-functional catalytic converter** on the cylinder bank 1. However, this may be a consequence of the **50% richer** cylinder bank. **First, replace the high-pressure fuel pump**, then burn out the catalytic converters thoroughly by driving in a very sporty manner, and finally perform another log analysis.

### Repair Recommendation:
**Replace the high-pressure fuel pump.**

Obrázky, fotografie a soubory

Engine with direct fuel injection (18803/11)

Estimated repair costs at an authorised BMW workshop (18803/12)

The replacement of the following parts was recommended to the customer.

Partly warm engine (about 40 °C) (18803/14)

Fuel Trim adaptives in negative values (–30%) on both cylinder banks (B1 and B2)

Multiplicative adaptives = OK (18803/15)

The adaptives under engine load are completely OK.

Engine under load = OK (18803/16)

All engine parameters are OK.

Bank 1 adaptives (–50% (!!!); Bank 2 (–20%) (18803/17)

Engine idle after a long drive. There is a large difference in adaptives between both cylinder banks. The values are reaching high negative values. The difference between the individual Banks is 30%! The engine crankcase oil is contaminated with petrol. The first cylinder bank receives more petrol vapours.

Timing advance retarded (18803/18)

At the same moment, the spark occurs after TDC. However, this has nothing to do with the mixture enrichment fault! It is the response of the control unit to the oscillating signal from the monitoring lambda sensor on cylinder bank 1 (B1S2). The control unit sees that the catalytic converter is not functioning and attempts to heat it up during this idle phase by applying negative ignition timing. In vain. The converter face is probably already coated in carbon deposits at this point.

The monitoring Lambda sensor on Bank 1 (B1S2) oscillates and this isn't correct (18803/19)

Either the converter is defective or the front face of the converter is covered by soot. The soot is the result of the mixture being strongly enriched by the crankcase vapours that include fuel.