10 Things You Need to Know about Engine Tune-Up’s

Aug 1, 2016

PART One:  What is a Tune-Up?

Mechanic Blaine MNThe Ignition systems works together with the fuel management system to provide a vehicle operating properly.  What is generally considered the tune-up today is just the replacement of the spark plugs.  The tune-up is listed in the Recommended Maintenance list as a preventive maintenance procedure at a specified mileage.  Some vehicles have what is called “coil over plug” ignition systems.  That means there is an ignition coil over each spark plug and no spark plug wires.  This tune-up amounts to replacing the plugs and inspecting each coil and coil insulation boot.  I can’t recall ever recommending that all the coils be replaced at once as that would be very costly.  The next type of ignition system (mostly on older vehicles) has a distributor, coil, spark plug wires and plugs.  This type of ignition system tune up normally replaces the distributor cap and rotor, wires, and plugs.  As the engine installations became more complicated this type of ignition system was replaced as they were expensive and difficult to maintain.

There are combinations of these two systems, but the bottom line is to know what mileage the tune-up is due at, and to get an estimate of its cost.  That tune-up estimate can vary from quite reasonable to extremely expensive.  The cost varies depending on the type of ignition system, engine and how it fits into the vehicle.  The point being you need to get a cost estimate, when the mileage that the manufacture is recommending approaches.

PART Two:  What is The Ignition System?

The ignition system is comprised of many individual sensors and other parts.  The ignition system provides the spark for each cylinder spark plug, at the correct time, causing the cylinder to fire the mixture of compressed air and fuel.  The major components are the computer, coils, spark plugs, plug wires, numerous sensors, and a battery.  You can expect to do repairs to the ignition system that is not a tune-up.  There is no set maintenance schedule for ignition system repairs other than a tune-up. Ignition system failures generally will set the check engine light.  So in and of itself the tune-up is not rocket science, but other ignition system repairs can be difficult to diagnose.

Another compounding factor is what other repairs that might be required in the near term that may share labor time.  Ignition systems have many moving and electronic parts; are complicated, and many failures exhibit the same symptoms. The fact that there are repairs to the ignition, that many call a tune-up, can make it even more confusing.  These ignition system repairs generally require a diagnostics test following a protocol shown in our diagnostics library.  The recommended tune-up does not require other things to be done with it, and is again considered preventive maintenance, requiring no diagnostics.

PART Three:  What is the fuel system?

The fuel system is also comprised of many individual sensors and other parts.  The fuel system provides the fuel mixed with air to each cylinder at the correct time to be ignited by the ignition system.  The ignition system and fuel system work together and their repair and maintenance can get very intermingled and or confusing.  As with the ignition system, failures is this system will generally set the check engine light. The major components are the fuel pump, fuel filter, air cleaner, throttle body, intake manifold, injectors, fuel regulator, and computer.

The only preventive maintenance procedure in the fuel system is the fuel and air filters.  The replacement times are listed in the recommended maintenance schedule.  Yes, the ignition and fuel systems share the same computer.  The troubleshooting of these two systems requires experience, special equipment, and diagnostic data support.  The poor old fuel filter perhaps is the most neglected part on the average car.  When they go bad the result can cause premature fuel pump failure, the car may not run and can be a diagnostic nightmare.

PART Four:  What is that Pesky Check Engine Light?

In general its appearance on your dash is to inform you that the computer has detected a problem, requiring a repair to the ignition or fuel systems. The problem is significant and caused by readings or sensing that is outside of the factory specifications.  There are a couple hundred reasons for this light to be on, each being called a fault code.   Each fault code has a diagnostic procedure that is many steps long and can lead to many different recommended repairs.  Not all fault codes will generate a customer complaint, so the first thing a good mechanic will ask about is what the observations of the customer are.  As long as your vehicle is running properly, has full power, the alternator light not on, and not overheating you may proceed and get it scanned at your earliest convenience.  If the car is not running right, immediate attention is required.

Yes, there are some cases when the check engine light repair can be deferred till a better time.  Then again there are fault codes that must be fixed very soon, if not immediately.  If the check engine light is flashing at you, the engine has a serious misfire and must be repaired immediately, to prevent destroying the very expensive catalytic converter.  Each fault code falls into three categories. The first is called a pending (soft) code, some computer sensing’s out of specifications, but intermittent, the light may even turn off.  It is still recorded in the computer for future diagnostic support.  The second type of fault code is called a current (hard) code.  The computer is getting sensing consistently out of specification.  The third type of fault code is called a historic fault.  There was a time when sensing were out of specifications, but in the past.  Most historic codes turn off the check engine after a specified number of drive cycles.  Not all fault codes turn on the check engine light, but are still recorded in the computer for diagnostic purposes.

When your car is running poorly and the check engine light is on we recommend that your vehicle be diagnosed and repaired.  The reason being, when your car is running poorly it is causing other damage that will cost you even more latter.   Not all problems will set the check engine light, but may cause you’re vehicle to not operate properly.  There are at least three, if not five computers in the modern vehicle.  All set fault codes, many of them not being allowed to turn on the check engine light.  Some of these codes are so important that additional lights have now been placed in your dash.  The Anti-Lock Brake computer will set the ABS light and the red brake light.  The body controller will set the check vehicle soon light as well as other lights.  The transmission controller generally sets the check engine light.  The heating and air conditioning controller normally sets no lights, but can be scanned.  The low Tire Pressure module will set the TPS light.  Finally the traction Control computer has now even been given its own light.  These all make for future articles.

PART Five:  What is the Computer?

The modern vehicle has three or more computers.  The computer operating the ignition and fuel systems, relative to the tune-up, is called the Electronic Control Module (ECM) or the Power Control Module (PCM).  I’m sure in some engineering circles there is a reason for both terms existing, but I have not crossed it.  Because of the complexity of these computers they get condemned a lot as the reason for the observed complaints.  In the process of troubleshooting it is the last item listed in the test sequence, due to expense and frankly they generally are not the problem.  If there is a problematic PCM or ECM, for that specific model or make of car, we get what is called factory service bulletins or factory recalls.  These bulletins and recalls tell the technicians in the field what problems have been observed in enough quantity to deserve information being published about it by the factory.

Because these are in fact computers, technicians are always warned about protecting them from voltage spikes during repairs.  That is why Jump Starting your neighbor’s car is less popular, due to the risks of voltage spikes.  Battery chargers and jump start boxes are much preferred.  The PCM or ECM is the controller of the Ignition and Fuel Systems and turn the check engine light on when there is a problem detected.  The computer is where the fault codes from the check engine light are recorded and stored.

The Computer is accessed through a data port.  The structure of the data port has been regulated for many years (all cars use the same data port) called OBDII.  Data ports prior to the early 90’s varied with every manufacture and or model car.  Repair shops are hard pressed to hook up the cars prior to OBDII, because they no longer have those cables or scanners.   Needless to say there are volumes of material we could cover here, but just knowing that there is a computer in the ignitions system is the goal.

PART Six:  What is Diagnostics or Troubleshooting?

The question is, can knowing what the fault code is, tell you what is wrong with your vehicle?  A reputable shop will scan your automobile’s computer codes free.  They will give you some recommendations about an organized way to proceed with the repair of your vehicle.  But alas, just knowing the code generally will not identify exactly what to do.  That takes us to troubleshooting, which is the process of specific diagnostic tests to the ignition and fuel system to identify what repair is needed.

When the mechanic starts the troubleshooting process the worst things you can, do as the customer, is tell the technician what to fix.  Some shops will do what you have asked them to do, and then call you and tell you what really needs repair.  A good example of this would be your car is misfiring and you’re asking for a tune-up.  The shop looks at the fault codes and determines that the fault codes are for lean bank one and bank two as well as a code for random misfire.  You are 40,000 miles short of the recommended tune-up, which is over $300 dollars.  The real cause may not the tune-up, but rather vacuum leaks, exhaust leaks, or fuel management problems, requiring diagnostics.

The process of troubleshooting the automobile of today is compounded by the complexity as well as the intermingling of the many operational systems on today’s cars.   There is the transmission shop that starts to do tune-ups, because so many people bring cars in for a transmission repair, when it really needs a tune-up.  There is the ongoing mystery of the car not running correctly and it ends up being an exhaust repair for a plugged catalytic converter.  There are things that you as the vehicle operator can do to save you money.  One, think a about what it is that constitutes your complaint.  Does it miss only when first started or only after fully warmed up?  Is the lack of power only exhibited when at highway speeds?  Is the backfire only when decelerating?  Does the engine seem to be running too cold and your complaint is poor fuel economy.  These observations along with the fault codes will help orientate the diagnostics and allow for a more effective repair.

 PART Seven:  What is the recommended Maintenance Schedule or Preventive maintenance?

When you get a different (new) car it has a list of recommended maintenance repairs at certain miles and or months of operation.  If you don’t have that list in the owner’s manual then you can get those on line or at most repair shops.  Bottom line is you need to know when specific maintenance items such as the tune-up are due i.e. 30,000 miles, 80,000 miles etc.  The reason is that as you affect maintenance (Oil Changes) many repair facilities will recommend maintenance procedure early.  The tune-up of your engine is one.  The factory recommended maintenance schedule can be considered as preventive maintenance.  Preventive maintenance is designed to replace various parts at a time before they fail and cause problems.

Just because the check engine light is on at 65,000 for any of a couple of hundred reasons, does not mean you need a tune-up.  A very high percentage of tune-ups are not due till 100,000 miles.  Most small shops will scan your computer and identify a list of the fault codes at a minimal charge or free.  I provide a code scan free of charge and provide some impute to you as to what type of trouble shooting may be required or what type of repair you may be looking at.  Just knowing the code in most instances will not direct the specific repair.  It will only tell you which system or parts are not operating within factory specifications.  This brings me back to the tune-up.  Many shops recommend a tune-up early even when the required repair is something else.  How do you know when you need one?

First, a very high percentage of the tune-ups done at Clark Automotive are done many thousands of miles after the recommended miles.  This is possible because, needed check engine light repairs were done soon after the light comes on, thus causing less stress on the engine management systems.  Many times you can manage your car maintenance expenses by knowledgeable deferring of repairs till a better time.  A case in point, I recently observed a new customer experience their truck jerking and the check engine light blinking continually.  They had brought it to the local parts store and were told, “You have a misfire on cylinder # 3”.  They still have 40,000 miles till the recommended tune-up time.  What parts to replace?  A friend had suggested a tune-up, and says they will help because they have experience.  An afternoon later and some expenditure on parts they start the truck up and still have the light on.  They then contacted Clark Automotive Clinic for a free scan and recommendation.  We recommended a trouble-shooting session at a $30.00 charge.  The resulting repair was accomplished with parts (An ignition coil) and labor at $90.00.  A replacement of the spark plugs (Tune-up) was not needed.

The lesson to take from the above case is that there can be many possible solutions that cause the problems you may be having with your truck.  Knowledgeable trouble shooting can save you money and time.  The tune-up on most vehicles today is to replace the spark plugs.  In many cases the correct spark plugs a very exotic and high priced.  The ignition system has much more to it than spark plugs, but those parts are replaced as needed, generally because they fail, causing a unacceptable complaint and the check engine light to be on.  If this happens before the plugs need to be changed only the repair of that failed parts is needed.

PART Eight:  What tune-up parts to use?

A reputable shop should utilize parts equal to or better than the Original Manufacture (OEM) Parts.  Many parts are upgraded after the car is manufactured and specific problems start to arise.  Again these issues are published in Factory Service Bulletins and if serious may end up being a Factory Recall.  An example is the common problem of conducting the Tune-up on certain Ford Pickups.  These Spark plugs are recommended to be replaced at 100,000 miles.  What happens is many break off during removal. There are numerous articles published on how to successfully do this tune-up and how to remove the broken spark plugs.

Each customer and the repair shop may have automotive part brand preferences.  Getting together with the repair shop to select the desired parts is important before the tune-up is started.  The selection of parts can have a bearing on quality, price, availability, compatibility, and factory recommendations.  Generally the manufacture recommends regular (Copper), platinum, double platinum, iridium, etc.  There are some aftermarket tune-up products that fall outside those factory recommendations and should be used with great caution.  When it comes to the older cars using spark plug wires we use wires with a life time warranty (just in case they break).

PART Nine:  What about aftermarket treatments and additives relative to the discussion of the Tune-up?

I was just asked about fuel treatment procedures conducted by the many oil change places.  There is a time and place for Fuel treatments, following factory recommendation as shown in service bulletins.  These are not part of an oil change!  These are specific and recommended repair procedures utilizing specific chemicals in a specified manner.  The need for fuel injector cleaning as part of an oil change, and is not recommended by most automotive manufactures.  In fact all gasoline dispensed by gas stations in most states contains the required amount of cleaners and additives.  There was a time in the far ago past when certain additives did have a place, but that is very rare today.

Oil additives on the other hand, are a much harder subject to address.  Generally speaking there is not a need for these additives in a well running vehicle nor do automotive manufactures recommend any.  In fact there are numerous service bulletins explaining what the harmful affect are.  In the case of an old tired engine there may be some appropriate applications of some additives.  In general than there is no need for you the vehicle owner to be spending money on additives and cleaners unless executing a factory recommended service procedure.

PART Ten:  Will high octane gas make my car run better?

Another question in the tune-up area often asked is, “Will high octane gas make my car run better”?  There is no manufactures recommendation to use premium unleaded fuel in a regular unleaded fuel car.  For those cars where premium fuel is recommended it can make the car operate at its full potential.   For vehicles recommended to use regular unleaded gas it will generally not and is for the most part a waste of money.  It works like this; high octane gas burns slower.  The additives between high octane and regular unleaded gas, is generally the same, for the various oil companies.  Using slower burning gas is of no advantage in a vehicle designed to run on regular unleaded.

For the vehicle recommended to use premium it is advisable to do so.  But, we recently had a customer who had put regular unleaded gas in their high performance Chevrolet.  They had been told they needed to get that gas removed immediately, or it would ruin their engine.  Not the case, we informed them that conservative operation for a half a tank of gas would be well advised, then fill it up with high octane unleaded. Although prolonged use of low octane gas in a high-compression engine that requires high octane will prove problematic and cause the engine to knock and potentially cause damage.

What to do if you put the wrong fuel in?
First, addressed in a separate issue, putting regular unleaded in a premium unleaded vehicle is not advised.  When this error is made it does not require a repair procedure, just a bit of conservative driving.  That is not the case if you put gasoline of any kind into a diesel operated vehicle.  Do not operate this vehicle!  Have it towed to your repair facility to have the fuel drained and replaced with diesel.  Putting diesel into you gas operated vehicle is not quite as serious, but still do not drive the car, as it won’t run well anyway.  Have it towed into your repair facility and the fuel corrected.  The last indiscretion is putting E85 into a regular unleaded fuel vehicle.  You are generally going to be headed and perhaps towed to your repairs shop to get the fuel switch out.

Make sure all operators of your vehicle are aware of the fuel requirements.  The Gas stations have done what they can to display the different fuels in a manner that does help us keep it straight.   Thankfully this is not an everyday problem.

The last thought on this subject is vehicles designed to operate on E85.  We have had a couple of high mileage cars that had never run on E-85, and it was finally used, but would not run right.  The E85 management system needed to be repaired or E85 use terminated.  There are some fuels now at different ratios of alcohol, E35.  We will address that at a later date.

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