What does engine misses mean

Call it scientific method, with some sensible leaps. As for knowledge, if your car or truck is computer-controlled, the place to start is to plug in. Okay, six cylinders of potential problems have just been narrowed to one. Had we not been computer controlled, studying the spark plugs would have helped focus on possible sources of a misfire. Before you get started, however, be sure to follow all the car maintenance safety protocols with goggles, gloves and whatever else is needed.

Diagnose and investigate: Ignition Choose your plan of attack — cheap to expensive, easy to difficult — and stick to it. Because the P had repeated, the 4 plug came out first.

It read lean a gray-brown, not bad but trending hot and fuel-starved , predictive of a fuel problem rather than a spark problem. The repair and replacement R and R of fuel injectors is a bigger project than the plugs, so we stuck to the plan and stored the knowledge in case ignition repairs failed to fix things.

The other plugs had been replaced about 20, miles earlier and looked almost ideal. Every one was in good shape, short of the lean read on 4. We cleaned them up and swapped the plug on Hole 4 with 2. If the problem were the spark plug, the misfire would move to 2.

P came back. Plug read: ash-brown with a hint of green — good mixture on late-model engine. Touch of gray from hot, hard run up and down Black Mountain. White flecks, bad gas? Plugs good, plug wires not? Those on this truck were as old as the truck itself and probably original, so even though they ohmed out fine and looked good — if dusty — at , miles, it was not hard to justify a new set.

There are a few easy ways to test plug wires. Examine them in the dark, engine running, and watch for sparks jumping. Next, mist the wires with water and see if this causes any sparks in the same dark environs.

Surging can be related but not necessarily. Except in the rare case where ignition timing wanders distributor based systems had this problem sometimes when they got old, but todays cars control ignition timing much more reliably , surging is generally a fuel metering problem. Again, there are a number of possible causes including but not limited to vacuum leaks and flaky fuel pressure regulators. Milady, would you like me to recommend some good books on automoyive fundamentals?

You sound like the kind of person that is an obsessive-compulsive reader who would really benefit from good texts. In the worst-case scenario, a continuing misfire could cause some costly problems that could effectively destroy your engine. One of the worst culprits, a cylinder misfire, can cause a host of problems starting with your catalytic convertor.

As the inside of the catalytic converter heats up it can start to break apart, plugging the exhaust, which causes problems to keep cascading. Excessive oil consumption can heat the cylinder up, creating preignition which in turn slows the engine down and damages crankshaft bearings.

The heat that is generated can warp or crack valves and the cylinder head. One of the first things you mechanic will do when you present a car with a misfire is to check for diagnostic trouble codes DTCs. An engine misfire code might indicate a problem with a specific cylinder, or that the engine is running lean.

Depending on the diagnostic tool being used, it may show how many misfires occurred within a certain number of cycles, or the engine RPM when the misfire occurs.

Not all misfires will cause a DTC to be logged, however, particularly if the misfire is intermittent. Vehicles showing any of the above DTC codes should not be driven due to the potential for unsafe vehicle operation and driveability concerns.

In short, if you suspect your engine is misfiring, make an appointment with a mobile technician from RepairSmith as soon as possible to have your vehicle inspected and repaired and to prevent further damage. But before you call to make an appointment, collect as much information as you can , including any peculiar sounds, to assist your technician in diagnosing the problem.

Take note of any unusual sounds or behavior, and under what circumstances the engine is misfiring, such as if it occurs immediately after the car has started if the misfire occurs under acceleration or at idle, and how frequently you notice the misfire occurring. The more information you have, the easier it will be for your mechanic to find the cause of the misfire.

You should not continue driving with an engine misfire. Is Your Engine Misfiring? Here are 6 Possible Causes April 8, Here is what a mechanic might find when diagnosing the issue: 1. Ignition system problems When most people hear the term misfire, they think of worn out spark plugs. Air and fuel delivery problems Air and fuel mix together inside the engine, then the mixture is ignited by the spark plug.

Emissions equipment problems Late-model cars have an array of emissions equipment that helps minimize the amount of pollution released into the atmosphere. Control circuit problems All of the input and output engine management devices i. What Causes A 4 Cylinder Misfire?

Possible causes of a cylinder 4 misfire include: A damaged fuel injector Sticking valves Faulty spark plugs Worn coil packs Defective injector circuit Bad catalytic convert e r Low fuel pressure Leaking head gasket Faulty oxygen sensor Defective mass airflow sensor Faulty throttle position sensor Any of these components can cause a cylinder 4 to misfire and be the root cause of a P engine code.

However, a misfire will be considered in conjunction with the following signs: Check engine light Engine stalling Rough idle Slow acceleration Excessive fuel consumption Hard starting the vehicle Low fuel pressure Low compression When Does My Engine Misfire?

Diagnosis of Common Engine Misfire Codes One of the first things you mechanic will do when you present a car with a misfire is to check for diagnostic trouble codes DTCs. The following codes may indicate a potential misfire: P — P Mass airflow sensor P — P Lean or rich fuel mixture P Fuel injector circuit malfunction P Random misfire that is not isolated to one or two cylinders.

P Misfire in cylinder 1 P Misfire in cylinder 2 P Misfire in cylinder 3 P Misfire in cylinder 4 P Misfire in cylinder 5 P Misfire in cylinder 6 P Misfire in cylinder 7 P Misfire in cylinder 8 Vehicles showing any of the above DTC codes should not be driven due to the potential for unsafe vehicle operation and driveability concerns. Car Care Advice.