Why does the new Jetta have fuel injection pulse width but no ignition signal?

[LeHope]

Reasons for the new Jetta having fuel injection pulse width but no ignition signal: weak spark plug ignition energy, insufficient low-pressure fuel supply. Weak spark plug ignition energy: Some car owners, in order to save money, do not replace the spark plugs after the maintenance cycle, which leads to a significant drop in spark plug ignition energy and even misfires in severe cases. Moreover, many current models use direct-injection engines, which place higher demands on spark plugs. Insufficient low-pressure fuel supply: Insufficient oil pressure in the low-pressure fuel circuit directly causes the engine to require a second ignition. The specific reason is that the first ignition fails to start the car because the low-pressure fuel circuit is building up oil pressure, and the second ignition can start the car. Specific components to check: fuel pressure regulator, fuel pump, fuel filter, and internal pipelines.

[IkerLynn]

I remember encountering this issue last year when repairing a new Jetta for someone. The fuel injection pulse width was normal but there was no ignition signal – really annoying. This is most likely due to a faulty crankshaft position sensor, as it provides the ECU with signals to control ignition timing. The fact that the ECU can output fuel injection commands indicates its fuel delivery function is still operational, but there might be a short circuit or open circuit in the ignition system. Check the ignition coil, high-voltage wires, and related wiring connectors – look for corrosion, looseness, or burn marks. It's recommended to use a diagnostic tool to read fault codes, which often show P0340 or similar. Don't attempt DIY fixes to avoid damaging the engine; get it professionally serviced promptly. This kind of failure prevents the car from starting and could easily leave you stranded, posing significant safety risks. Regularly cleaning sensor connectors during maintenance can help prevent minor issues.

[AbelFitz]

I've been driving for several years and encountered similar situations. When starting the new Jetta, the engine cranks but fails to ignite. The mechanic said there's fuel injection pulse width but the ignition signal is missing. The cause might be simple: loose wiring of the crankshaft sensor or a burnt coil. Poor contact due to aging wiring is also common, especially after rainy days or bumpy rides. You can try visually inspecting the ignition components, but don't touch the high-voltage wires randomly—safety first. ECU failures are rare, but once they occur, they're troublesome. I recommend going to a 4S shop or a reliable repair shop for a check first. The diagnostic fee isn't high, and replacing a small sensor or coil might solve the problem. If left unrepaired, each start wastes fuel and can easily lead to carbon buildup, affecting subsequent driving.

[SanCecilia]

As a frequent visitor to car enthusiast forums, let's talk about this issue. Having fuel injection pulse width but no ignition signal usually indicates a problem with the crankshaft position sensor or ignition module. The ECU controls fuel injection but the ignition process is interrupted—a faulty sensor can't provide ignition commands. Short circuits or poor connections in wiring can also cause this. During diagnosis, checking the spark test of the ignition coil can confirm the issue. Repair it promptly to avoid startup failures or roadside breakdowns, which can also damage the engine. Replacing a sensor isn't a big deal, but professional testing is more accurate.

[DiAdalynn]

I enjoy researching car issues on my own. When there's fuel injection pulse width but no ignition signal, start with simple checks: see if the ignition coil connector is tight, and if the crankshaft sensor plug is loose. If the high-voltage wire is burnt black, it should be replaced. ECU or control line faults are more complex; you can use a multimeter to test voltage, but don't experiment without experience. Remember to check the relevant fuses in the fuse box. Not fixing this not only makes starting difficult but also wastes fuel and increases pollution. For safety, it's recommended to have a professional technician diagnose the issue, as they have comprehensive tools and high precision. During maintenance, clean electrical connectors to prevent similar faults.

[VanWalter]

Worried about car repair costs? Let me break it down. For the new Jetta, normal fuel injection pulse width but missing ignition signal is often caused by a faulty crankshaft position sensor - a small part that costs just a few hundred to replace. Ignition coil failure is similarly affordable. ECU issues or wiring problems may cost more. Always have a technician diagnose to avoid unnecessary expenses. When experiencing faults, avoid frequent starting attempts to protect battery and engine. Failure to start may lead to unexpected parking situations, which can be dangerous. Regular sensor checks and cleaning prevent minor issues, saving both money and hassle.