Misfire and drivability complaints with misfire codes are very common at your shop. How do you deal with those complaints?
What often gets left out is asking your customer how long has the misfire been going on? The longer a misfire is plaguing an engine, the chances of damaging the catalytic converter are a lot greater. Here’s what to know about a misfire: you have fuel and air going into the cylinder that is not ignited because either the spark plug is not working or the timing is off.
That air and fuel then gets put into the catalytic converter. When it’s there, it ignites and creates heat and possibly damages the ceramic substrate inside the catalytic converter.
This is why it’s critical to understand how long that misfire has been occurring and extending your diagnostic process to a catalytic converter. In some cases, it is going to be clogged. In some cases, the efficiency numbers are not going to be there, and you may have a P4020 code.
When this happens, you’ll need to do further diagnosis on the vehicle. Still, that question must be asked: how long has this misfire been going on? If the customer says more than a week, chances are the converter could probably be damaged due to the severity of the misfire from that vehicle.
So just keep these two things in mind. If you have a misfire code, make sure you’re checking downstream, because if that spark plug is not firing well, the air and fuel, will be going into the catalytic converter getting burned and causing higher temperatures.
