FAQ
TL;DR: After refueling, a 2011 VW Touran 2.0 TDI lost power and misfired; "4 injections went to pizza" and all 4 injectors were replaced, tank cleaned, and the issue vanished. [Elektroda, OTOLIT, post #16685132]
Why it matters: If your TDI runs unevenly right after a fill-up, bad fuel can take out multiple injectors fast—diagnose before you drive further.
Quick-Facts
- Reported symptoms: uneven running, power loss, hard/no start right after a full refuel. [Elektroda, OTOLIT, post #16638411]
- OBD initially flagged cylinder 4; after clearing, no codes reappeared despite misfire. [Elektroda, OTOLIT, post #16642009]
- Unplugging injector 4 made no difference; engine only ran on three cylinders when forced. [Elektroda, OTOLIT, post #16642614]
- Compression test showed 28 atm on three cylinders and 18 atm on cylinder 4. [Elektroda, OTOLIT, post #16646530]
- Root cause and fix: contaminated fuel damaged all four injectors; replacing 4 injectors and cleaning the tank solved it. [Elektroda, OTOLIT, post #16685132]
Quick Facts
- Reported symptoms: uneven running, power loss, hard/no start right after a full refuel. [Elektroda, OTOLIT, post #16638411]
- OBD initially flagged cylinder 4; after clearing, no codes reappeared despite misfire. [Elektroda, OTOLIT, post #16642009]
- Unplugging injector 4 made no difference; engine only ran on three cylinders when forced. [Elektroda, OTOLIT, post #16642614]
- Compression test showed 28 atm on three cylinders and 18 atm on cylinder 4. [Elektroda, OTOLIT, post #16646530]
- Root cause and fix: contaminated fuel damaged all four injectors; replacing 4 injectors and cleaning the tank solved it. [Elektroda, OTOLIT, post #16685132]
What were the first symptoms after refueling?
The car began to run unevenly, felt like it was “not burning all cylinders,” lost power, and then wouldn’t restart after stopping. This followed a full tank fill-up. These symptoms point to fueling or injection issues that appeared immediately after the refuel event. [Elektroda, OTOLIT, post #16638411]
Does this 170 PS 2.0 TDI use piezo common-rail injectors or unit injectors?
It uses piezo common-rail injectors, not unit injectors. A forum expert emphasized that these piezo CR injectors are costly and require proper diagnostics before replacing parts. "A decent diagnosis is essential." [Elektroda, ledka, post #16645977]
What did unplugging injector 4 reveal?
Unplugging injector 4 made no difference to engine behavior, confirming that cylinder was already inactive. The engine could be made to run on three cylinders only when forced, which further implicates injector 4 or its cylinder. A slight idle knock was also noted. [Elektroda, OTOLIT, post #16642614]
What did the scan tool show for cylinder 4?
The scan initially reported an error for cylinder 4. After clearing the code, no new codes appeared, even though the cylinder stayed inactive. Transient faults can clear if not re-detected immediately. [Elektroda, OTOLIT, post #16642009]
What were the compression test results in this case?
Compression measured about 28 atmospheres on three cylinders and only 18 atmospheres on cylinder 4. That delta indicates a significant mechanical or sealing issue for that cylinder and warranted deeper inspection at the time. [Elektroda, OTOLIT, post #16646530]
Could contaminated fuel actually kill multiple injectors at once?
Yes. The owner reported contaminated fuel, after which all four injectors failed. Replacing all four injectors, refilling with clean diesel, and cleaning the tank resolved the problem completely. "4 injections went to pizza" was the on-thread description. [Elektroda, OTOLIT, post #16685132]
What finally fixed the Touran’s uneven running and no-start?
Replacement of all four injectors with tank cleaning and fresh fuel. After this work, the engine behavior normalized and the problem disappeared. This confirms the failure was tied to fuel-borne injector damage rather than wiring alone. [Elektroda, OTOLIT, post #16685132]
Is it safe to keep driving if there’s knocking at idle during a misfire?
No. The case documented a slight knock at idle with a dead cylinder. Continued operation risks further damage and unburned fuel wash-down. Stop, diagnose, and repair before road use. [Elektroda, OTOLIT, post #16642614]
How do I quickly isolate a dead cylinder on a CR TDI?
Try a controlled injector unplug test.
- With engine off, unplug the suspected injector’s connector.
- Start and observe changes; restore connection, then test another cylinder one-at-a-time.
- Compare behavior to identify the inactive cylinder.
Perform only if you’re trained and safe. [Elektroda, goldwinger, post #16642205]
Why did the fault code disappear even though the misfire stayed?
The code for cylinder 4 was cleared and did not immediately return. Intermittent or threshold-based detection can delay re-logging, especially if conditions for the fault are not met during a short test. [Elektroda, OTOLIT, post #16642009]
Can starting fluid help in diagnosing fuel-system faults?
In this thread, the engine fired when assisted with starting fluid, then ran poorly. That behavior points away from immediate low-compression no-start and toward fueling or injection problems to investigate first. [Elektroda, OTOLIT, post #16640570]
Could misfueling with gasoline have caused this? How to verify quickly?
Misfueling was suspected, but the owner verified diesel at the filter. A quick check is to inspect the fuel in the filter housing. If appearance or smell is wrong, drain and test before running. [Elektroda, OTOLIT, post #16640570]
Are these injectors Bosch or Siemens on this vehicle?
Despite an early guess of Siemens for the 170 PS variant, the owner confirmed Bosch injectors on this car. That detail matters for testing and replacement choices. [Elektroda, OTOLIT, post #16642009]
Could a shorted injector cause sudden rough running?
Yes. A contributor suggested that on 170 PS setups, an injector can fail by short circuit, causing misfire and loss of power. Electrical checks should accompany fuel tests. [Elektroda, 1769758, post #16638740]
Does high mileage alone explain this failure?
The vehicle had about 260,000 km with no prior issues reported. The sudden onset immediately after refueling points to the fuel event, not wear-only aging, as the trigger. [Elektroda, OTOLIT, post #16640570]
