What causes random cylinder misfire?

A random misfire code usually means the air/fuel mixture is running lean. But the cause might be anything from a hard-to-find vacuum leak to dirty fuel injectors, low fuel pressure, a weak ignition coil, bad plug wires, or compression problems. The first thing to check is the intake vacuum with a vacuum gauge.

How does the PCM know which cylinder is misfiring?

The OBD II system detects misfires on most vehicles by monitoring variations in the speed of the crankshaft through the crankshaft position sensor. Whenever crankshaft rotational velocity varies by just 2 percent, one or more misfire codes are stored in the memory of the PCM.

How do you tell what is causing a misfire?

The PCM can detect when a cylinder decelerates (an indication of a misfire), store a Diagnostic Trouble Code (DTC) in memory, and turn on the Check Engine Light. Some car computers detect misfires by measuring electrical activity [ionization] at the spark plug electrodes.

What causes misfire at low rpm?

Many system malfunctions can cause misfires or rough idling. Ignition system components, including spark plugs, plug wires, ignition coils and ignition timing are culprits as are lean air/fuel mixtures and mechanical issues within the engine.

How many misfires are normal?

Normally it’s less than 10 misfires but there always seems to be a couple no matter what, like I said, especially at first start up, cold. What exactly is a misfire? Should I be concerned? Should I monitor something else at the same time that I am not thinking about?

What to do if your Acura has a misfire?

We replaced that with a bolt and gasket (washer) from Acura (PN 90009-R70-A00 and 94109-14000 if you were curious). After all of this work, the engine is still spitting out the same codes. The engine’s running much more powerfully now, so it’s like an amplified version of the original problem.

What is the Check Engine light on Acura CL 3.2L?

I’m working with our 2002 Acura CL 3.2L. The engine is running very rough at idle (it sounds like a muscle car). I have two lamps illuminated on the dashboard. The Malfunction Indicator Lamp (MIL) is flashing, and the Traction Control System light is solid. NOTE: Some bulletins refer to the MIL as the Check Engine Light (CEL) as well.

Why is exhaust gas clogging on my Acura?

Purely running off of the feedback of the lamps, I did some online research and found this to be common issue with Exhaust Gas Recirculation (EGR) System Port Clogging. It didn’t take much to pull the intake manifold cover plate off of the engine and have a look.