FAQ
TL;DR: Typical M47 pre-supply is about 3.5 bar; “0.8 bar is not enough.” If your E83 2.0d stalls on cold start, verify low-pressure fuel delivery first. [Elektroda, Cobrat, post #17065172]
Why it matters: This FAQ helps BMW E83 2.0d owners fix cold-start stalls faster and avoid misdiagnosis.
Quick Facts
- Typical common-rail pre-supply pressure ≈3.5 bar; 0.8 bar is insufficient. [Elektroda, Cobrat, post #17065172]
- Common symptom: cold starts, stalls 2–3 times; warm starts are instant. [Elektroda, sly_1978, post #17060657]
- Priming by cycling ignition 2–3 times improves cold starts. [Elektroda, sly_1978, post #17060657]
- Confirmed fix shared: EWS 3+ → EWS 4 plus new K96 and K2003a relays. [Elektroda, marcin.dziubczyk, post #19207029]
- Some M47 cars have a second lift pump under-floor near the driver’s seat. [Elektroda, xxxkubek, post #17063894]
What fuel pressure should the in-tank pump provide on a BMW E83 2.0d?
Typical common-rail pre-supply is around 3.5 bar. 0.8 bar is too low for this system. “0.8 bar is not enough for this system.” Measure at the feed line with a gauge. If pressure is low, test the lift pump and its power supply before chasing injectors. [Elektroda, Cobrat, post #17065172]
My X3 starts, runs 2–3 seconds, then dies when cold. What fixed it for others?
One owner solved this by replacing a faulty EWS 3+ with EWS 4 and renewing two relays: K96 (fuel pump) and K2003a (ECU power). The car had no codes and would die after 2–3 seconds. After these parts, cold starts were reliable again. [Elektroda, marcin.dziubczyk, post #19207029]
Why does cycling the ignition two or three times help a cold start?
Cycling the ignition primes the low-pressure circuit. The OP reported that turning to ignition two or three times helps cold starts. He suspected fuel reversing, which points to supply-side issues like drain-back or a weak lift pump. [Elektroda, sly_1978, post #17060657]
Does the M47 in the E83 have a second low-pressure pump?
One contributor reports a second pump under the car near the driver’s seat. It sits roughly below the seat, along the fuel lines. Inspect your specific car for this configuration. If present, test that auxiliary pump as part of your diagnosis. [Elektroda, xxxkubek, post #17063894]
Where are relays K96 and K2003a, and what do they do?
K96 is a bright green relay behind the glovebox powering the fuel pump. K2003a is a blue relay in the left engine bay powering the ECU. Replacing both resolved cold-start stalls for one owner. [Elektroda, marcin.dziubczyk, post #19207029]
Could the glow plug controller cause hard cold starts on this engine?
Yes. A failing glow plug driver can cause difficult cold starts on BMW diesels. A contributor flagged this as a frequent culprit. Scan the glow system and verify the controller and plugs before deeper fuel work. [Elektroda, xxxkubek, post #17064518]
I can’t see fault codes or parameters. What should I do first?
Restore the ECU’s error table to regain diagnostics. A user recommended this step when codes and live data were missing after changes. “So it’s best to restore the error table.” [Elektroda, piotrekwoj1, post #17061210]
Could previous DPF modifications block diagnostics?
Yes. The OP indicated a DPF modification had been done, and afterward he could not see parameters or errors. Revert such changes or reflash to stock to restore diagnostic visibility. [Elektroda, sly_1978, post #17061086]
How do I prime the fuel system before a cold start?
Use the ignition-cycling method the OP found helpful:
- Switch ignition ON for 10–15 seconds without cranking.
- Switch OFF and repeat 2–3 times.
- Start the engine and observe idle stability. [Elektroda, sly_1978, post #17060657]
Is a 0.8 bar low-pressure reading acceptable on this common-rail system?
No. The system expects around 3.5 bar pre-supply. “0.8 bar is not enough.” At 0.8 bar, expect cold stalls and poor priming. Investigate the lift pump, filter restriction, and wiring for faults. [Elektroda, Cobrat, post #17065172]
What’s at the fuel filter on the E83 2.0d—pump or heater?
On the OP’s car, the unit at the fuel filter location is a heater, not a pump. Verify your vehicle’s configuration visually before ordering components. [Elektroda, sly_1978, post #17064053]
Should I replace the fuel filter during diagnosis?
Yes. Confirm the fuel filter service history and replace it if unknown. A contributor raised this check early because restriction there starves the low-pressure side and worsens cold starts. [Elektroda, xxxkubek, post #17063894]
Warm starts are perfect. Does that rule out fuel supply problems?
No. In the thread, warm starts were instant yet cold starts stalled. Ignition cycling helped, which points to priming or supply issues. Do not rule out low pre-supply pressure or air ingress. [Elektroda, sly_1978, post #17060657]
I have the same issue—what’s the most likely fix from this thread?
The only confirmed resolution shared was replacing a failed EWS module and renewing relays K96 and K2003a. After that, the engine started reliably from cold. Use this path after verifying pre-supply pressure. [Elektroda, marcin.dziubczyk, post #19207029]
. If I'm wrong, somebody correct me, but 0.8 bar is not enough for this system.
