What is the reason for a car having fuel, spark, and cylinder pressure but not starting without any faults?
3 Answers
This situation may be caused by damage to the ignition system. After encountering this issue, it is recommended to check the ignition coils and spark plugs. The operation of a car engine depends on the ignition system. If the ignition system fails to spark, the combustible mixture in the cylinder cannot ignite. Relevant details are as follows: 1. Spark plugs: The ignition coil and spark plug are the main components of the ignition system. The spark plug is a wearable part that requires regular replacement. The spark plug has electrodes that can release sparks. However, as usage time increases, the electrode gap of the spark plug will gradually widen, leading to weaker ignition energy. If the ignition energy weakens, it will affect the engine's power and fuel consumption. 2. Ignition coil: If the spark plug is not replaced for a long time, the electrodes of the spark plug may fail to release sparks. The ignition coil is used to connect the spark plug, and its function is to increase the voltage. Only with sufficiently high voltage can the spark plug release sparks.
I've encountered this issue quite a few times. No trouble codes, fuel and spark present, plus cylinder compression, but the car just won't start—it's really frustrating. The main cause usually lies in system coordination, such as a faulty crankshaft position sensor or camshaft sensor, which prevents the ECU (Electronic Control Unit) from properly controlling ignition and fuel injection timing. Even though there's spark and fuel, if they're mismatched, it's like adding seasoning in the right amount but at the wrong sequence when cooking—the engine simply won't fire. If the timing belt is off by a tooth or two, it can also throw off compression and ignition alignment. I've seen cases where ECU programming issues or poor wiring connections caused this—everything seems normal on the surface, but the engine won't run. I recommend immediately scanning with an OBD diagnostic tool and avoiding DIY fixes. Take it to a professional repair shop to check the timing and sensor components—safety first. Once resolved, you can drive without worries next time.
My car once had the same issue, and it drove me crazy! I checked all the basics: fuel line clear, spark plugs firing, cylinder pressure up to standard, but it just wouldn't start. After racking my brain, I found out it was a minor fault with the camshaft position sensor—the ECU wasn't receiving the correct signal, causing the ignition timing to be off. Also, if the timing chain or belt isn't aligned precisely, even a slight mismatch between the compression stroke and spark timing is like dancing off-beat—the engine just won't start. I once overlooked an ECU firmware issue too, which was resolved after an update. This experience reminded me how crucial small details in a car can be; don't just focus on the major components. Now, during regular maintenance, I always ask the mechanic to check these areas to avoid breakdowns on the road. You'd better get a comprehensive check-up done ASAP—don't end up struggling late into the night like I did back then.
