FAQ
TL;DR: On Audi A4 B6 1.9 TDI PD, “beep/BIP” readings can be ~40–50; “Corrections are, but still normal.” Use Group 18 and basic electrical checks before replacing injectors. This FAQ helps owners understand uneven idle, high corrections, and BIP values. [Elektroda, daro_p, post #17127634]
Why it matters: You can avoid unnecessary injector replacements by confirming simple, cheaper causes first.
Quick Facts
- Group 18 should show 0 at idle; brief deviations up to ~4 can appear on a throttle blip. [Elektroda, daro_p, post #17127634]
- Start with simple checks: improve injector 1 and 4 electrical connections; verify synchronization. [Elektroda, daro_p, post #17127665]
- To confirm a bad unit, swap injectors (e.g., 3 and 4) and repeat the readings. [Elektroda, daro_p, post #17127739]
- Seal failures can cause severe BIP (e.g., −50) and 3‑cylinder running; replace copper washer and O‑ring. [Elektroda, marszałekkom, #17129528]
- Use new stretch bolts: injectors 12 Nm + 270°, rocker shafts 20 Nm + 90°. [Elektroda, masay1, post #17130147]
What do “corrections” and “BIP beeps” mean on a 1.9 TDI PD?
Members use these readouts to judge injector behavior. Beep/BIP values around 40–50 appear in healthy engines. As one expert said, “Corrections are, but still normal.” Focus on outliers rather than chasing zeros. [Elektroda, daro_p, post #17127634]
Which injector looked weak in this thread’s case?
Members pointed to cylinder 4. One reply stated, “No. 4 looks the weakest.” Recheck after any wiring or seal work to confirm. [Elektroda, Trawik, post #17127579]
Are modest positive idle corrections considered normal?
Yes. The shared logs showed corrections present, yet within acceptable behavior. As noted, “Corrections are, but still normal.” Focus on symptoms, not chasing zero. [Elektroda, daro_p, post #17127634]
My cylinder 4 correction rose from +0.99 to +1.2; what should I do next?
Document the trend, then inspect cylinder 4. Remove the injector and check its gaskets and the electrical connector. The author planned this because seals can influence corrections. [Elektroda, hunter999, post #17127845]
What should I check before replacing a PD injector?
Start with low-cost checks. Improve electrical connections and verify timing synchronization. If needed, swap injectors (e.g., 3 and 4) and repeat the readings. Check the tandem pump’s fuel-side efficiency. Replacement is costly, so rule out simple causes first. [Elektroda, daro_p, post #17127739]
How do I check tandem-pump fuel pressure on this engine?
The tandem pump has a port for a pressure gauge. Connect a gauge to measure fuel-side performance. Weak fuel delivery often shows as negative BIP and uneven running. Repair or replace only after confirming pressure. [Elektroda, daro_p, post #17127794]
Does firm brake feel rule out a tandem-pump issue?
No. The tandem unit handles vacuum and fuel pressure. Good brakes prove vacuum, not fuel pressure. As noted, “air and fuel pressure — separate topics.” Test fuel pressure independently. [Elektroda, daro_p, post #17127952]
What should Group 18 show at idle and during a blip?
Expect zeros at idle. During a quick throttle blip, temporary deviations up to about 4 can appear. Sustained deviations suggest an electrical or injector issue that needs attention. [Elektroda, daro_p, post #17127634]
I briefly see “127” in Group 18 after a throttle blip. Is that bad?
One report showed 0 at idle and brief 127 spikes during blips. Use this as a clue, then confirm with other checks and readings. [Elektroda, hunter999, post #17127646]
Can a worn dual-mass flywheel cause wavy corrections or idle shake?
Yes. If dose adjustments are wavy, check the dual-mass flywheel condition. Start with the simplest solutions first, including connector checks on injectors 1 and 4. [Elektroda, daro_p, post #17127665]
Can leaking injector seals cause negative BIP and misfiring?
Yes. One case showed −50 BIP and the engine running on three cylinders. A failed copper washer let compression past, then the O‑ring failed. Replacing seals restored BIP near 0, though worn sockets may limit longevity. [Elektroda, marszałekkom, #17129528]
What torque and hardware should I use when reinstalling PD injectors?
Use new bolts only. Torque injector hold‑downs to 12 Nm, then add 270 degrees. Torque rocker‑shaft bolts to 20 Nm, then add 90 degrees. As advised, use “only New” fasteners to protect head threads. [Elektroda, masay1, post #17130147]
Is a budget 3/8″ torque wrench accurate enough for this job?
It can work for undemanding tasks. Where higher precision matters, it is a bit too weak. Choose a better tool for injector and rocker fasteners. [Elektroda, masay1, post #17131195]
How can I isolate a weak PD injector quickly?
- Improve electrical connections on injectors 1 and 4.
- Swap injectors, for example 3 and 4.
- Repeat the readings to see if the fault follows the injector. [Elektroda, daro_p, post #17127739]
Could a middle O‑ring leak cause overflow and negative BIP?
Yes. A leaking middle O‑ring can route fuel to overflow. The ECU increases dose, and low pressure yields a negative BIP. Fix the seals first. [Elektroda, marszałekkom, #17127945]
The pump tends to operate in two areas - air and fuel pressure - separate topics.
