What's involved in a car tune-up?
July 28, 2009 2:30 PM   Subscribe

Car care: (1) How often, generally speaking, should I change my spark plugs and plug wires? (2) When a vehicle gets a "tune up," what, exactly, does this mean? What gets tuned? Thanks!
posted by jackypaper to Travel & Transportation (12 answers total) 3 users marked this as a favorite
Depends on the age of the car.

On most recent cars original plugs are made to last 100,000 miles.

On older cars without fuel injection, a tuneup means replacing the plugs, and then points and condenser. And then adjusting the carburetion. But most cars in the past 15 or so years do not have those parts, nor do they have carburetors. So, "major maintenance" usually includes changing out the timing belt, and maybe changing transmission fluid, as well as the plugs and plug wires (or however the plugs are connected).

YMMV. . .
posted by Danf at 2:36 PM on July 28, 2009

FYI, replacing the plugs and wires yourself is a fairly easy task. They screw in/out without a problem.

Changing a timing belt or chain seems like a very labor intensive process (I've never done it, but I've read the manual to see what needs to be done).
posted by spikeleemajortomdickandharryconnickjrmints at 2:41 PM on July 28, 2009

Speaking really generally, I'd say new plugs and wires approximately every 30-50 thousand miles. At Audi, all of our cars call for new plugs at 55k or before. There may be plugs that claim a 100k lifespan, but every manufacturer that I can think of calls for plug replacement before 60,000.
Plugs may be changed more frequently on an older (pre 1990) car.
It'd be really helpful to know what kind of car you're talking about. Your owner's manual will have a schedule in it.

"Tune up" is somewhat of an antique term. Old cars required adjustments in regards to ignition timing and fuel mixture. New cars run on non-adjustable computer control so a "tune up" these days will consist, generally, of new filters (fuel and air) new plugs and wires (unless it's coil-on-plug), maybe a fluid flush of sorts, and some places will clean the carbon out of the throttle body and even run a solvent through the fuel injectors. Nothing gets "tuned" on a new car, just refreshed or restored.
A timing belt is typically a major service all its own and a major "tune up" style service is performed a half the timing belt interval. For example, a 50k will be a major tune up and 100k will involve a timing belt and water pump replacement.
posted by Jon-o at 2:44 PM on July 28, 2009 [1 favorite]


Not always; the link also gives some info about the increased lifespan of modern spark plugs. Your owners manual will tell you what is recommended for your particular car or you can probably find the info on the internet.
posted by TedW at 2:51 PM on July 28, 2009

In addition to the above, nowadays a "tune-up" will usually include a "thorough 40 point inspection", many of which will include mundane things like looking at the tires, checking their pressure, making sure the headlights work, etc. All for the low low price of $399.00 (or some ridiculous price).

I'm not saying it's a waste to have your car checked by a professional, but a lot of what you get is really straightforward stuff.

When in doubt, your owner's manual will tell you appropriate intervals to change things like air filter (very easy), spark plugs (usually easy), oil (easy but messy), transmission fluid (not always easy, messy), timing belt (professional time for most people), etc. These can vary widely by vehicle and usage.
posted by Big_B at 2:53 PM on July 28, 2009

1) It depends, somewhat, on the age and condition of your vehicle. Late model cars with modern high voltage electronic ignitions, platinum spark plugs, and fuel injected engines, dynamically "tune" themselves, to a great degree, and the reduction of moving parts, and better materials mean you may only need to replace your plugs and spark plug wires every 60,000 or so miles. Older cars, from the 70s and early 80s, often had semi-mechanical ignitions and fuel metering systems, with a rotating spark distributor and mechanical ignition points, as well as a carburetor for mixing fuel and air, all of which needed much more frequent adjustment and/or replacement, perhaps as often as every 10,000 to 12,000 miles. Follow your owner's manual service recommendations, for the type of driving that you do.

2) Again, it depends on the age and condition of your vehicle. In a modern car, there will be recommendations for inspection and replacement of various ignition and fuel system components at 30,000, 60,000, and 90,000 mile intervals (and thereafter, at generally 30,000 mile intervals). Air filters and fuel filters should be changed on schedule, or as dirt found in inspection dictates. Spark plugs and wires will usually be replaced at 60,000 miles. On fuel injected cars, fuel pressure and flow are usually checked when the spark plugs are replaced. Spark timing may be checked with a timing light, but rarely needs to be adjusted. Oil and lubrication services are also generally done at "tune up" intervals, although they should also be done at recommended intervals in between. Engine accessory belts, hoses and vacuum lines, and valve timing belts are also generally checked and replaced as needed.

On older Detroit V8 cars, a 12,000 mile tuneup used to typically include replacement of air filter, oil filter, fuel filter, and an oil change, as needed. Then, spark plug replacement, inspection/replacement of ignition points and condenser, check of spark coil output voltage, test/replacement of spark plug wires, replacement of spark plugs, adjustment of ignition timing and dwell, cleaning and inspection of carburetor, adjustment of idle mixture, check of carburetor accelerator pump function, carburetor float valve level, and a check for vacuum leaks. Inspection of engine accessory belts and hoses. About every 24,000 miles, a cooling system service was also usually done.
posted by paulsc at 2:54 PM on July 28, 2009

A note about spark plugs - internet forums devoted to your car's model are a fantastic resource for this sort of thing. On some cars the coils mount just above or on the spark plugs, and you need to be careful not to damage them while you are working or you are going to start spending a lot more money. I've learned some very valuable tricks on reading forums and can chance the plugs on our 4-cylinder car in five minutes. I have yet to attempt this on my v6.
posted by Big_B at 2:56 PM on July 28, 2009

Wellll...sort of. Many modern cars have individual ignition coils on each plug. Some of them can be downright fragile to remove intact(*COUGH*vw*COUGH*) In other instances, some plugs are almost unreachable. The rear bank on my Maxima, for instance (my aching back!) But, yeah, in general, plugs can be pretty easy. Definitely something a first-time DIYer should have no problem tackling.

Timing belts should be done only by someone who really knows what they are doing. Serious damage can be had if done wrong. Timing chains rarely, if ever, need replaced. Our Maxima has over 300k on it and the timing chain has never been serviced.

Re: "Tune-ups"...A couple months ago, we took one of our cars to the local Midas (I know, I know) for brake work. While there, a woman came in and asked about getting a tune-up for her recent-vintage mini van. To my astonishment, the manager told the woman that, for modern computerized cars, there really was no such thing as a "tune-up" anymore. They would hook it up to the diagnostic equipment, see if there were any trouble codes, check the fluids and pads and that's about all there is, unless the computer finds a problem. I was simply amazed that he didn't just say "Sure, we can do a tune-up" and rob her for $300 or something. I was impressed with the honesty.
posted by Thorzdad at 3:17 PM on July 28, 2009

Generally the term for tune-up is inspection. There is usually a minor and a major, call your dealer and ask them what they do for each.

Here's a quick list of what is usually done for BMW Inspection I/II, I would expect similar for your car.
posted by wongcorgi at 7:26 PM on July 28, 2009

Agreed- no more such thing as a tune up.

My experience: I've had a couple of cars with the 100,000 mile plugs in them, and they did last 100,000 miles. The KEY point when using platinum plugs is to know whether your car uses a "waste spark" system. If it does, you MUST use double-platinum plugs. A dollar or two more a piece, but without that, the plugs eat themselves alive. Also, the spark plugs (in this sort of modern vehicle with the platinum plugs) usually aren't the cause of any problems. They just don't wear out they way they used to.

All cars need these days is maintenance.

-Oil according to the preferred schedule.
-Air filter should be checked often, and replaced when it's dirty. (This *can* make a huge difference.)
-If the manual suggests changing the timing belt, it is usually a good idea to do so when they suggest it. When they fail, they can cause a lot of problems.

If you start getting drivability issues, things to check are spark plug wires, oxygen sensor(s) and MAF/MAP sensors.

Other than that, pretty much just fix stuff when it breaks.
posted by gjc at 7:31 PM on July 28, 2009

If you have the owner's manual for your car, it will have this information in it, as well as the schedule for all other maintenance. Depending on the car, you may be able to find a .pdf of the owner's manual online.
Like other posters have said, modern cars don't really need to get "tuned" the way older cars with carburetors and points did.
posted by zombiedance at 10:34 PM on July 28, 2009

Even if your car calls for plugs only after 100,000 miles, I'd still jump the gun and replace them as early as 70k. Not because the plugs won't last, but because of the increasing difficulty and risk of extracting the plugs. Most new engines have aluminum cylinder heads and at high mileage, after being heat soaked for about 7 or 8 years, the steel threads of the spark plug aren't so willing to unscrew. In the past, I've had three spark plugs SNAP OFF AT THE NUT on high milage cars. A 4.3 Blazer, a 3.0 Ranger, and a 3800 Impala, each with about 100-120k on them. Also, if a spark plug wire goes untouched for 100k, it becomes practically welded in place and the amount of effort to remove them is totally unreasonable, especially on a front-wheel drive V6 like the 3800. The rear plugs and wires are subjected to so much un-dissipated heat. I have vivid and unpleasant memories of sitting on top of the engine in that Impala, struggling to my wits end to remove the spark plug wire in one piece, and the feeling totally sick in my stomach when the spark plug snapped of. Then, I spent the next several hours extracting the old plug, having to view the whole process through a mirror since I couldn't fit my head between the firewall and the cylinder head. I had to chip the old porcelain insulator out of the core and then clear the threads without allowing the metal into the combustion chamber. It sucked.
There is absolutely ZERO harm in changing your plugs early, but the longer you put it off, the more stubborn they become.
posted by Jon-o at 4:09 AM on July 29, 2009

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