Engine misfired during smog check
My engine misfired when doing the smog check.
Experienced mechanics share their insights in answering this question :
If your engine has a misfire then that can occur for a number of reasons. If it suddenly occurred during a smog test then something may have been knocked loose during the inspection. It is not uncommon to have a vacuum hose come loose and cause this. If it is not a hose then it may have a bad ignition coil or spark plug. The computer would need to be scanned for codes to see which cylinder is misfiring. A mechanic would use the codes to determine if one of these parts is bad and to possibly check the compression of the engine. I recommend that you have your engine misfiring issue diagnosed and repaired as soon as possible to prevent further damage.
How to Identify and Fix Common car Problems ?
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If your engine is misfiring it will not pass a smog check. The engine needs to be in good running condition in order to pass.
Bad Spark Plugs
Bad and worn spark plugs make your engine misfire. It is this misfiring that may cause your vehicle to fail the smog check. You need to have a fully operating ignition system in order for your vehicle to pass. If the spark plugs are bad, you may end up with a failing grade.
A clogged or failed exhaust gas recirculation or crankcase ventilation valve or faulty oxygen sensor can send the wrong signals to the computer and cause misfires.
The OBD II system detects misfires on most vehicles by monitoring variations in the speed of the crankshaft through the crankshaft position sensor. A single misfire will cause a subtle change in the speed of the crank.
The short answer is yes. Your vehicle can pass the smog check with a pending trouble code, so long as the check engine light is not illuminated and the required emission monitors are ready. A pending trouble code may set for diagnostic purposes and will not illuminate the check engine light.
A misfire will cause the engine to momentarily stumble, or lose rpms, and then regain its normal engine speed. The misfire will usually reappear, either under specific operating conditions or randomly. A misfire may occur when your engine is idling, causing a rough or uneven idle.
If you car fails a smog inspection or if you fail to get a smog inspection once every two years, then you will not be allowed to renew your car`s registration with the DMV. As a result, you will not be able to legally drive that car on the street.
Get Rid of Your Check Engine Light
If your check engine light is on, you`ll automatically fail your smog test. In the State of California, your auto mechanic cannot refuse to test your car if they see the light on.
The most common causes of misfires are worn, improperly installed, and mishandled spark plugs, malfunctioning ignition coils, carbon tracking, faulty spark plug wires and vacuum leaks.
Yes. While the damage may seem small initially, the longer you drive with a bad oxygen sensor, the worse the damage will become. Eventually, you may experience rough idling, poor acceleration, engine misfires, an illuminated check engine light, and failed emission tests.
P0420 means the catalytic converter is not efficiently removing pollutants from the exhaust. Your car won`t pass an emissions test. A bad catalytic converter isn`t a hazard to the driver but it can overheat and destroy engine components.
How are PDTCs going to be used as part of a Smog Check inspection? Upon implementation, vehicles that have a PDTC stored in the OBD system will fail the Smog Check inspection regardless of whether the malfunction indicator light is illuminated.
This is called detonation, and worn spark plugs cannot ignite the mixture properly. Consequently, there will be unburned gases that make their way from the combustion chamber to your vehicle`s exhaust, and this will cause your vehicle to fail the emissions test.
Dirty fuel injectors may cause your vehicle`s engine to misfire. This problem makes the motor feel as though it is sputtering — sending vibrations through the car. Such misfires can happen when a fuel injector problem mixes up the delicate balance between fuel and air entering the engine.
Worn spark plugs
While small, spark plugs are among the most critical parts in your engine, unfortunately, they can also lead to a failed car emissions test.
Faulty spark plugs could lead to increased fuel consumption and higher emissions as mentioned earlier.
Your spark plugs generate the spark your vehicle needs to start. They are set to fire in a specific order and they if fail to do so, your car, truck, or SUV could fail its emissions test. In most cases, misfiring is caused by old and worn-down spark plugs. If it`s time to replace them, do so before your test.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
2006 Ford Mustang has check engine light on
ANSWER : There are countless potential causes for your illuminated check engine light. The mechanic manually turned off the light, but it came back on because the problem has not been fixed. The first place to start is retrieval of the stored diagnostic trouble codes (DTCs). These codes serve as a starting point for any further diagnostics a mechanic may perform. Codes will be stored anytime the check engine light is on. Since the first mechanic was unable to fix your concern, I recommend giving the professionals at YourMechanic a call. We offer expert check engine light diagnosis and repair.
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Engine misfires and check engine light is always on
ANSWER : It’s always a good idea to pull over and turn off your vehicle when the check engine light is blinking. A blinking check engine light usually means there is a severe misfire in one or more of the cylinders. Most of the time, a misfire symptom is the result of a fouled spark plug. Honda now recommends changing spark plugs at 110,000 miles, however it is a known fact that spark plugs are considered a wear item and they do indeed wear out. There are a lot of factors that go into a spark plug wearing out or prematurely wearing out. One thing to consider is the type of gasoline being used in the vehicle. A top tier gas is recommended in most newer vehicles. This is because top tier gas contains additives which keep the engine free of deposits that may cause spark plugs to foul prematurely.
Honda is aware of this concern and has issued a technical service bulletin to help reduce and, in some cases, eliminate this concern. This technical service bulletin advises the technician to update the vehicle’s engine computer. This update improves fuel injector and variable camshaft timing during cold starts and eliminates excessive fuel from fouling out the spark plugs. I recommend you have a certified mechanic inspect your ignition system to determine the exact cause of this misfire so the proper repairs and preventative maintenance can be performed and get you back on the road again.
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Check engine light refuses to go off after engine replaced
ANSWER : Hello there, you have a long series of issues going on with your 2013 Hyundai Sonata. If you keep getting a repeating oil light on than there is likely a fault in that system.
Since this fault has lasted after the engine was replaced it could be a oil pressure sensor, wiring harness fault, ECU fault, oil pump, oil strainer clogged, or low oil pressure.
To diagnose this issue properly you need a complete vehicle inspection to start from square one and identify the root cause of all this.
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Reduce engine power / check engine light is on
ANSWER : Hi there. Most of the time, reduced engine power is caused by a restriction of fuel, or the throttle body’s inability to efficiently mix air and fuel. This could be caused by a failing mass air flow sensor, EGR valve or other fuel system components. Since the check engine light is on, you should have a professional mechanic complete an inspection at your location to determine what codes are stored and which components require repair. This should resolve your issue.
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Check Engine Light comes on after starting pickup
ANSWER : Hello there, thank you for asking about your 1992 Isuzu Pickup. A professional will have the correct equipment to read OBD1 codes. Retrieving the diagnostic trouble code(s) is the first place to start when diagnosing your vehicle. Increasing RPMs changes engine load, which can in turn affect many different sensors and components, causing the Check Engine Light to illuminate. The only way to narrow down the options and find the culprit is through in person diagnosis with an OEM compatible scan tool. A certified technician from YourMechanic can retrieve the OBD codes at your home or office.
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O2 sensors changed, but check engine light still showing code after clearing it I checked fuse. Wires are good and used Denso OE.
ANSWER : Depending on what the code was for will determine if the oxygen sensor was to be replaced. If the conditions were for a rich or lean mixture and it said oxygen sensor, then the spark plugs and wires could need replaced if its a rich reading or the fuel injectors could be clogged or not working if its a lean mixture. If the code said that the oxygen sensor was bad, then check the harness and see if there is a break in the wiring or a short to ground in the wiring from the oxygen sensor to the main harness. If you need further assistance with your check engine light being on, then seek out a professional, such as one from Your Mechanic, to help you.
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p0011 code,check engine light one, changed bank 1 vvt solenoid and check engine light still on?
ANSWER : The P0011 code is typically caused by oil issues with the car. I would particularly make sure the engine oil level is not low. The VVT solenoid relies on proper oil levels to do their job. If they don’t have enough oil, they won’t work. You can have a mobile technician from YourMechanic visit your home or office to inspect the Check Engine Light for you. If you follow through with a repair with us you will be reimbursed for the cost of inspection.
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Check Engine Light is on and engine is quaking and stalling – 2006 Mercedes Benz C55 AMG
ANSWER : Hello. If the Check Engine Light has come on, then that means the computer has detected some sort of issue. I would rescan the computer to see if the same code has returned, even after cleaning the sensor. If cleaning the MAF did not clear the code, then it is likely that the MAF sensor needs to be replaced. When changing out the MAF be sure to replace it with a high quality unit (an original equipment piece if possible), as a low quality,or low budget MAF can sometimes cause issues. Usually a MAF sensor replacement is quick, and aside from clearing the code, it can help keep the vehicle running at maximum efficiency.
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