What causes missing in an engine?
Engine misfires can be caused by a list of faults, but there are a few suspects that occur more than others. The primary villains are simple – spark or fuel – usually manifesting in spark plugs, plug wires, the coil(s) or the fuel-delivery system.
Will misfire cause engine not to start?
Hi There, Generally a misfire in one or two cylinders may not prevent the car from starting, however depending on how severe the misfire is, it may be possible. Engine misfires can be caused by many different problems and are generally caused by either a spark or fuel issue or in some cases, a combination of both.
What causes a Toyota 4Runner to have a lean idle?
If the engine smooths out and HC drops and remains stable, the problem is a lean idle condition. Check for dirty injectors, low fuel pressure or a defective fuel pressure regulator. If HC still fluctuates, however, the engine is still too lean in one or more cylinders indicating a vacuum leak.
How do you find a misfire code on a Toyota 4Runner?
If a misfire is occurring in only one or two cylinders, you will usually find a misfire code for that specific cylinder rather than a random misfire code. Start by checking engine intake vacuum. Connect a vacuum gauge to a vacuum port on the intake manifold. Start the engine and note the vacuum reading.
Why does my Toyota 4Runner fail emissions test?
The fuel mixture is too lean to ignite reliably so it often misfires and fails to ignite at all. Lean misfire will show up as elevated hydrocarbon (HC) readings in the exhaust, which may be enough to cause a vehicle to fail an emissions test. Hesitation or misfiring when accelerating.
What causes a vacuum leak in a Toyota 4Runner?
An EGR valve that is stuck open at idle can have the same effect as a vacuum leak. So too can a loose positive crankcase ventilation (PCV) hose, a leaky PCV valve or the wrong PCV valve (one that flows too much air for the application). If somebody replaced the PCV valve recently, they may have installed the wrong PCV valve.