A misfiring engine is a very serious concern that demands immediate attention, unless of course you prefer to spend thousands of dollars on your car repairs.
What is an engine misfire?
It’s easiest to explain when you understand how an engine works. An internal combustion engine has several cylinders which continually fire in sequence creating a smooth flow of power and this propels your car. When the firing sequence is not smooth the engine has what is called a misfire. There are many causes from a bad spark plug, ignition coil, fuel injector or engine valve just to name a few.
When a misfire is present you will notice are several things: first the engine will shake or shutter either at a constant speed or when accelerating, and your check engine lamp may come on. Often the check engine lamp will blink and this indicates a catalyst damaging misfire. This is something to take very seriously and have repaired quickly.
When an engine misfires, a cylinder’s worth of raw, unburned fuel is exhausted through the catalytic converters and out the tailpipe. Any raw fuel in the catalytic converters quickly overheats them and leads to their destruction. If misfires occur severely then damage occurs quickly. If misfires are subtle, then damage may not occur for a year or two. When damage does occur expect to pay a lot to fix it. Most modern vehicles use what are called close coupled catalytic converters because they are integrated with the exhaust manifold and tucked up tight to the engine. On a V6 or V8 engine these are usually followed by another catalytic converter further downstream.
Over the years we’ve seen many vehicles that have experienced misfire concerns, fixed them after the vehicle was driven too long and then had the car return a few months later with either plugged exhaust and/or the check engine lamp on with a catalyst inefficiency code. It’s very predictable!
Recently we repaired a V6 equipped 2003 Ford Escape that had a couple of defective ignition coils that were causing a severe misfire. Several months passed and the vehicle returned with a plugged exhaust system. So severe was the blockage that it caused the EGR valve to blow apart. We dismantled the exhaust system, performed an inspection and found the front converter had partially melted, broke apart and sent particles to the rear cat, plugging it. After replacing these 2 cats and the EGR valve the engine’s power was restored but a further major exhaust leak was present from the rear exhaust manifold. Final repair bill: $3600 taxes in. Ouch! This happens more often than you think.
The good news it that it is completely preventable.
If your engine ever misfires get it fixed right away and save your money.
Some folks think that AirCare is a scam or at least a waste of time and I’m here to say that those thoughts could not be further from the truth.
We fix several cars and trucks per month and from experience I can say that the results speak for themselves. Check out the latest AirCare repair that we did on a 1995 Jeep Cherokee: the results are profound and just by fixing this one vehicle, less toxins are being released into our air.
Most modern cars, especially the new models are very clean and release mostly CO2 into the air. This is a global warming substance and of great concern.
However, the most toxic pollutants are carbon monoxide, hydrocarbons and oxides of nitrogen emissions and properly running modern cars minimize those pollutants.
Air Care’s purpose is to keep these toxic pollutants to a minimum and it does a great job of doing so by identifying vehicles which put out excessive emissions. If you care to know more about the hazards of these pollutants there are many websites with detailed information.
Before repairs this vehicle emitted the following amounts of pollution in 100 kilometers:
• 40 grams of hydrocarbons
• 664 grams of carbon monoxide
• 168 grams of oxides of nitrogen
After repairs this vehicle will now be able to drive:
• 5.7 times farther (571 kilometers) and emit the same level hydrocarbons
• 19 times farther (1900 kilometers) and emit the same level of carbon monoxide
• A whopping 83 times farther (8300 kilometers) for the same oxides of nitrogen pollutants.
These are big numbers that mean much cleaner air for all of us. Next time that you think that AirCare is a waste of time, please take time to reflect on these numbers.
Pawlik Automotive is a licenced AirCare Repair Center, and we have year after year maintained a 100% (or near) pass rating on our AirCare repairs including in the most recent 12 months.
We are Certified AirCare technicians which means that we have passed the required extra exams to get the certification. Not all AirCare repairs are created equal… call (604) 327-7112 to set your appointment with the Pawlik Automotive service team.
Catalytic converters fail for many reasons and the consequence of failure can cause several things to occur including a failed AirCare emission test, a check engine lamp warning, rattles under your car and poor engine performance.
Let’s look at what your catalytic converter is, what it does and what causes it to fail.
Catalytic converters use a catalyst to transform harmful carbon monoxide, hydrocarbon and oxides of nitrogen emissions in your engine’s exhaust into carbon dioxide and water. The catalyst consists of a combination of precious metals: platinum, palladium and rhodium. When the hot exhaust passes these elements a chemical transformation occurs.
The precious metal catalyst is bonded onto a very fine ‘honeycomb’ grid which sits inside the converter housing. It is a simple structure with no moving parts and only requires the heat of the exhaust and the right exhaust gas mixture to operate.
Catalytic converter failures occur in several ways: First, impact failures which can occur if the unit is hit, often involving running over something. Second, thermal shocks which can occur if the unit is suddenly cooled. A likely cause would be going over a puddle in cold winter weather and the hot converter receiving an intense dousing of cold water. Third cause of failure is poisoning of the catalyst which can come from several sources: use of leaded gasoline (very rare these days); antifreeze entering the unit likely through a blown head gasket or other internal engine coolant leak; use of improper silicone gasket sealers; and use of oil additives which contain zinc. Fourth, is coating of the substrate: this is the honeycomb structure with the catalyst. This can occur from excessive carbon deposits and/or excessive engine oil consumption. Fifth and final cause of failure is overheating of the catalyst and this usually occurs from too rich a fuel mixture and/or engine misfire.
While all manufacturers seem to claim that they don’t and that they last the life of the car, it simply isn’t true. Many cars experience early failure due to a substandard size or quality of converter. Aftermarket replacements, always much cheaper than the original manufacturer’s part, are usually inferior in quality.
There are various grades of aftermarket converters. Here, you truly get what you pay for as the cheap ones often fail quickly whereas the good quality aftermarket units usually give years of great service. This is why we always recommend high quality units.
As a conscientious car owner looking to maximize catalytic converter life the best thing that you can do is to maintain your car meticulously and always address any check engine lamp concerns, correct rough running and misfiring engines or any performance issues. Failure to do so will result in you buying new catalytic converter(s) sooner than necessary and these are, by the way, normally very expensive to replace!
For more on repairing Catalytic Converters here’s an article at AirCare
I am pleased to announce that our shop has won an AirCare Quality Repair Award. Very few technicians receive these awards and I am honoured to have met the criteria. To win this award a technician must perform a set number of repairs per year and have a passing average of 95%.
Our shop average over the past 12 months is 100%!
When you bring your vehicle to Pawlik Automotive you can count on receiving the finest AirCare repairs and service in Vancouver with a commitment to fixing your car properly: doing so not only keeps your vehicle running at its best, but also keeps our air clean.
Beware when buying a car maintained by a do it yourselfer!
We recently diagnosed an interesting AirCare failure on a 1993 BMW 320i that inspired me to reflect on the work that some do it yourselfers do. The vehicle failed for very high carbon monoxide and hydrocarbon emissions and while performing diagnosis and road testing I noted on our diagnostic computer that the engine’s coolant temperature was only reading 30 degrees Celsius with the engine hot. It should be at least 80 to 100 degrees!
The engine’s computer was getting the signal that the engine was cold and enrichening the fuel mixture and very likely causing the elevated emissions. Testing the coolant temp sensor and wiring was the next step. What I found here was amazing: the coolant temperature sensor was not connected and after an exhaustive search for the wiring connector I finally found it, buried under the intake manifold with another coolant temperature sensor connected to it sitting out exposed to the air! The sensor was reading the air temperature in the engine compartment. Why someone would go to such an effort to do something clearly so stupid is beyond me. Reconnecting the sensor correctly restored all concerns and the vehicle passed AirCare with great readings.
While there is nothing wrong with do it yourselfer work beware when you buy a car from such a person. Clearly this person had an idea of what they were doing but it made no sense and clearly showed that he had no understanding of what was required to keep a car running properly. This crazy repair not only created excessive pollution, it was also wasting gas in a big way.
If there is a lesson here to be learned, always ask who has maintained the car that you plan to buy: if the answer is “I did “or “my friend is a mechanic” be wary. You might just end up with this sort of horror story.