How do I know when it is time for a tune up and how much should it cost

The first indication that it is time for a tune up is when gas mileage begins to worsen.
You should always keep running tabs that show the average miles per gallon your vehicle is achieving. You can check the average mileage that you are getting and if the figures have begun to drop 10-15% there is a good chance that your automobile would benefit from a little TLC at a garage.
Of course there are some additional signs that can give you clues that let you know if your car could use a tune-up. When you perform routine tune-ups on a vehicle you are rewarded with better mileage and performance, but sometimes some small adjustments can be needed in between scheduled maintenance visits.
There are other reasons besides a tune up that could be the cause of many automotive woes, but this procedure will often clear up minor problems and it is relatively inexpensive.
Here are some of the top problems that occur in cars that are begging for a tune-up:
Misfiring of the engine becomes more frequent
Unusually rough running, engine coughs and sputters
Fast Idling is noticeable, especially when the engine is warm
Low power is obvious, especially on hills or when accelerating
Rough idling can be felt by the driver and passengers
Engine pings and knocks
Black smoke from the exhaust pipe
Engine continues to run for a few seconds after the car is turned off
Engine hesitation
Problems starting the engine
Usually you will notice more than one of these signs, and the more of them that are present, the greater the chance that you should take your car in for a check up soon. Some people have cars that may occasionally exhibit one or two of these problems; this is not necessarily an indicator that a tune up is in order. It is when these types of automotive symptoms suddenly occur that the alarm buzzers go off.
If you have been driving a car that has always had a little engine ping that you are used to hearing it may be very normal. You can ask a mechanic to check it out for you, but if your vehicle has already had an extensive work up and it is tuned to perfection, another tune up will not be necessary. There are some automobiles that have idiosyncrasies and if the problem is not major then you should not become overly concerned.
Proper maintenance will keep your car running longer and stay in better shape.
you can easily see that when you call around for an estimate you can get some pretty dramatic price differences. Most larger shops and all dealers that I am aware of will charge an hourly price for each job that is listed in a shop hourly manual. For example your car tune up might have an estimated repair or replacement time of four hours in the shop manual. This time is calculated using the shop hourly rate {i.e., 4 x $60}. Pretty straight forward right? Not all the time.So what do you get for the four hours of labor? If you call my shop and ask for a car tune up price we automatically figure in the price a fuel filter, spark plugs, air filter, PCV filter, and distributor ignition rotor plus all applicable labor charges. So my car tune up price would probably be much higher than a shop that only replaces spark plugs as their auto tune up package. You need to make sure you are comparing apples to apples when you are calling around for prices.Some shops that I know in my area purposely give low ball telephone estimates just to get you in the door. Example: You call to get a price for a new radiator installed. Does the estimate include new antifreeze, a new radiator cap and taxes? I would automatically figure these items in to my estimate, not only because I want to do a nice turn key job, but also I don't want to have to sell you parts later on that I already know you will need. For this reason, my phone estimates can be higher than some of my competitors, but your final bill might be lower. There are also different brands of shop manuals on the market, so the GM dealer would be using a different labor estimating guide than my shop and most independent shops would be using. Not only would these guides possibly give different replacement times, but they could also classify an auto tune up differently like in my example above. So the shop that you found only charged you for the time they actually spent working on the car? So is that a better deal? Maybe not, if all they did was replace spark plugs and call it a car tune-up. Just for grins you should call the dealer back and ask them how much they charge just for spark plugs. What if this shop has a slower mechanic, or deliberately takes longer to do the work just to rack up more time on the clock?On a different note, as a servicewriter, I would want to know why you are requesting a car tune up in the first place. What I have found is that if the car runs poorly or differently than normal, the customer often automatically asks for a car tune up. Cars of today are very sophisticated and full of computers and sensors that can cause your car to act strangely. So a tune up might not fix the problem, and a proper diagnosis from the mechanic could be beneficial