Need Help My Suv Is Misfiring

Can a bad car battery cause engine misfire?

So everyone on hear that says a weak battery cannot cause a misfire is wrong especially with a Subaru!!! I recently ran into this exact same problem with my 2013 Subaru Impreza 2.0L. My car began to have a rough idle anytime I was sitting at a stop light. Then the CEL came on for a misfire in the cylinder and the dealership wanted me to do $1000 worth of work replacing the coil packs and spark plugs. I specifically asked them if a weak battery would cause the problem and they said no as well. I knew my battery was weak because I couldn't leave my car radio on for 5 min with out the battery dying. All battery tests I did said the battery was fine. Today I finally got sick of having to worry about it not starting from leaving the door open or the radio on while it wasn't running. Sure enough my check engine light turned off and now my car has greatly improved performance! Also my car now idles like it is supposed to. I'm thinking my fuel pump was not getting enough power which caused the misfiring. Either way the problem is fixed and I suggest looking into the battery first!

What are cylinder misfire symptoms?

I'll add to the other answers,  if you are above 2500rpm, and the engine seems to abruptly sag (and also vibrates) as you gently increase the throttle to full throttle and recovers when you back off on the throttle : then this type of misfire is usually an ignition problem, most likely the ignition leads (especially if it's worse in the rain), or spark plug gap or plug fouling, or (for older engines, the distributor points are worn and the points gap is too large or too small) Arcing inside the distributor or across the coil also causes these symptoms. You can also have fuel related "misfires" too, a leaky injector will make one cylinder run really rich so it will run OK with normal loads , but idles rough, maybe some whitish smoke, smells like fuel in the exhaust.Another really obvious misfiring symptom is backfiring, backfiring can only occur when there is loss of spark.

How do I solve a cylinder 3 misfire?

Misfires are flagged due to lack of contribution from that cylinder. Lack of contribution means that that cylinder is not producing adequate combustion or no combustion at all.Misfires are caused by lack or weak spark due to faulty plugs, coils , coil wires, distributor caps ( if so equipped).Or, fuel issues, no fuel or too much fuel or too much air ( vacuum leak). Fuel related culprits could be injectors, clogged or not pulsing due to internal failure or drivers in the PCM or wiring to injectors.More serious issues are engine internals such as valves not sealing. Usually exhaust valves. Or worn cam lobes, or broken valve springs.So, eliminate the easy things first. Verify spark and measure strength of spark with a cheap spark tester. You should have a minimum of 30 KV jumping the gap. Swap plugs and or coils to see if the misfire travels to another cylinder.Eliminate fuel and vacuum leaks  issues with a propane test. Carefully introduce propane to the affected cylinder.

Why did my car shake and the check engine light flash while stopped at a light?

What you experienced was almost certainly a misfire event and the cause may be recorded as a diagnostic trouble code (DTC) in the engine controller’s memory. Most failures that are significant enough to cause MIL illumination will record a trouble code and its environmental/ data information from the moment, even if the MIL is no longer lit. Onboard Diagnostics work constantly to keep the MIL off, looking for a reason to turn the CE light out if the condition hasn’t been seen again recently, eventually even erasing trouble codes if all’s good. I can only speculate on the nature of your event, but a thorough scan to retrieve codes and freeze frame data of the moment will often shed some light on the situation.Misfires come in many flavors, ranging from slight loss of performance in a single cylinder, to one or more holes being completely dead. Your description of shake at an idle implies a power imbalance, which usually involves complete loss of performance, but just one hole.Barring an at-home scanner being available, rolling the ignition key from LOCK to RUN three times, then leaving it in the RUN position at the end will initiate the customer code-read feature, spilling any matured codes stored in the PCM through the instrument cluster’s odometer window. All codes will be four digits in length, beginning with the letter P, such as P0123. DTC information can be found at OBD2-OBDII Engine Light Trouble Codes Definitions, Description and Repair Information online.One-trip failures - those that have not quite matured - will not be displayed in this feature, but will show up on a high-end scanner if present.If only a single cylinder misfire code is retrieved, pull the coil and spark plug to inspect for signs of flashover - black marks on the upper spark plug insulator and inner coil boot that will not scratch off with a fingernail. Flashover is pretty common on coil-on-plug ignition systems and the cure is to replace both the boot and spark plug together. Worn plugs tend to incite this sort of situation as spark will always seek the path of least resistance.If your DTC list includes an injector control circuit code that matches the cylinder of misfire, chances are good that the injector is at fault. The injector may test as completely normal when cooler, but will go to an open circuit once heated, either naturally or with a heat gun.

I changed the spark plugs, Why is my engine light blinking now?

On most cars I’ve driven, a flashing check engine light means something is very seriously wrong. That means don’t drive the car till you’ve fixed it.An OBD2 scanner is pretty much a necessity for working on modern cars. They don’t even cost that much anymore. Plug it into your OBD port, and it’ll most likely tell you what’s happening to make the check engine light flash. Look up the code and error message on google or youtube, and you can most likely find a description of how to fix it.If it says something vague, and then think about what you did and what the problems might be. If changing the plugs was ALL you did, there are a few things that come to mind as the first things I’d check. Think about what you touched, and what those parts do for the engine. The plugs, wires and coil are all things you might have disturbed or miss-installed, and they all have to do with ignition. My thought is that you might have one or more misfiring cylinders. An engine will continue to run, although poorly, with a surprisingly large fraction of its cylinders failing to fire, but the computer that controls it will see this as a pretty serious problem, and either detect the misfires directly, detect the extra oxygen in the exhaust, or both.Are all your spark plug wires back in place and making good contact with the terminals, both at the plug end and the coil end?If you have ‘coil over’ plugs, are the connectors to the individual coils tight?Did you check gap on all your plugs before you put them in? If the gap is too small or too large, the plug can fail to spark or spark so weakly it doesn’t ignite the gas.Did you tighten all your plugs to the proper torque? A loose plug can result in a misfire due to lack of compression.Did all the plugs have their crush washers, or was one missing?Did you reinstall all the plug wires to the correct plugs, or are some of your cylinders firing out of sequence?Are all your spark plug wires in good condition, or were some damaged during your work? It doesn’t take much damage to high voltage wiring before sparks come out at the wrong places.Is the coil in good condition? Is it dry? If you had the hood open in the rain, a wet coil can malfunction, as rainwater is quite conductive at high voltage. The plastic shell on an old coil can get brittle, and working with it can crack the insulation. Oily gunk on the coil can bake into a carbon layer that’s conductive and short out the coil too.