Jason C
04-07-2005, 04:10 AM
http://www.quebectuning.qc.ca/ArtImages/24256/2.jpg
With the demise of the inferior points-type ignition system and the ubiquitous use of computer-controlled ignition systems, modern tune-ups are rather simple and not at all time consuming. In a typical tune-up, the cap, rotor, and spark plugs are replaced, assuming that everything else (plug wires, coil, etc) are fine. On an increasing amount of modern systems, there is no need to replace a distributor cap and rotor, since they come from the factory equipped with DIS.
However, the spark plug has not been eliminated, and it is a wear item that must be periodically replaced. Spark plug brand, design, and material are sometimes a popular subject of debate among automotive enthusiasts. In general, it is a wise idea not to deviate from whatever brand the car came spec'ed with from the factory. If the Chevy came with AC Delco, don't put some fancy Bosch Platinum +4 in the car. Whether it's a Mercedes or a Mitsubishi, sticking with what it came with originally is the safest way to go. Doing otherwise can sometimes make the car run better, but often is a recipe for misfires.
After doing some research on my car I found out that it came with NGK plugs stock. A bit of googling later, and I had found everything I needed (cap, rotor, plug wires, spark plugs) for a general tune-up.
http://www.ngksparkplugs.com/images/IridiumIXwithLeaderLines.jpg
The NGK Iridium IX is one of NGK's newest designs, employing a 0.6mm iridium center electrode. Most publications indicate that this is good for 60,000-100,000 miles (SAE iridium technical paper (http://www.sparkplugs.com/pdfs/iri.pdf)). I had briefly considered going with NipponDenso and their 0.4mm iridium plugs, but the added performance comes with a corresponding drop in durability. Mind you, the Denso Iridium will still outlast most Platinum plugs, nevermind a conventional Copper or Nickel design.
After some careful use of dielectric grease/antiseize, I started up the car and went on my way. First impressions: slightly smoother idle, noticeably smooth acceleration. Granted, the old plugs were pretty worn (roughly twice the spec'ed air gap before a temporary regapping) but it still felt nice.
Periodical replacement of the spark plugs is essential to prevent costly repairs down the road. Not keeping up with scheduled maintenance intervals can and often does produce a chain reaction of events. Example:
Your modern, DIS-equipped car won't start one day, so you have to tow it to the shop and service it. Turns out the ignition module is bad. No big deal, they're bound to go bad anyway. So you replace it and go along your merry way. Except that this isn't an archaic points type where the lobe grinds away at the plastic actuating piece. Your car doesn't have a distributor cap accumulating deposits over time and building up resistance. It just uses an ignition module, which in turn uses transistors to complete the circuit to ground. These suckers are pretty damn reliable. Isn't replacing one of them without further diagnosing kind of like replacing a burnt-out fuse without finding out what caused it to burn out?
Lo and behold, the new ignition module lasts a year before crapping out on you. Now you're scratching your head and you begin fuming as it hits you - that damn thing was replaced no more than a year ago!
Ignition modules can burn out just from exposure to underhood temperatures, but chances are the OEM knew about that and shielded the module sufficiently. More likely, an unacceptably high amount of current flow through the module caused by a short fried the transistors. What can cause this?
Well, when the module grounds the negative side, current from the coils passes through it. The worst enemy of an ignition coil is heat. If the coil gets hot enough, the thin winding inside said coil can melt and short together, creating a easier path to ground and thus zapping the module with way more current than it is rated to handle. The module won't be able to take this for long before giving up the ghost, possibly leaving you stranded on the side of the road - with virtually no prior warning that it's getting cooked by excessive current flow.
What usually causes a coil to overheat? Too much voltage passing through it! In the old days of points and even with the newer systems, too long of a dwell period can energizing the coil for too long and heat it up real quick. Modern computer controls do a good job of controlling dwell though. Something much more simple, like a worn-out spark plug can easily do it. What happens is that as the plug wears, the air gap slowly but surely increases over time. As this air gap increases, the amount of required voltage to jump the gap increases. When the coil is forced to provide this higher voltage it heats up beyond normal operating temperatures. This can only continue for so long before something has to give.
Now what? Well, a coil can start from between $25 - $50 each. The module costs at least $250, probably more if you drive one of them fancy imported luxury cars or flashy sports cars. :P And the spark plugs that started this whole chain of events will set you back about $50. Given about 1-2 hours of book time labor to replace everything at between $95 - $105 per hour on average, and you just set yourself back more than $500 bucks (conservative estimate ;) ). Some basic tools, antiseize, and your own purchased spark plugs wouldn't have cost you even $100, probably under $75. BTW, that estimate of 500 bucks doesn't include the first time you replaced the ignition module.
Don't skimp out on a scheduled tune-up! You may be able to stretch it out somewhat beyond what is *ideal*, but all you really end up doing is playing with fire - eventually, you're gonna get burned.
http://akimages.crossmediaservices.com/dyn_li/200.0.88.0/Retailers/AdvanceAutoParts/ngk_iridium_spark_plugs.jpg
With the demise of the inferior points-type ignition system and the ubiquitous use of computer-controlled ignition systems, modern tune-ups are rather simple and not at all time consuming. In a typical tune-up, the cap, rotor, and spark plugs are replaced, assuming that everything else (plug wires, coil, etc) are fine. On an increasing amount of modern systems, there is no need to replace a distributor cap and rotor, since they come from the factory equipped with DIS.
However, the spark plug has not been eliminated, and it is a wear item that must be periodically replaced. Spark plug brand, design, and material are sometimes a popular subject of debate among automotive enthusiasts. In general, it is a wise idea not to deviate from whatever brand the car came spec'ed with from the factory. If the Chevy came with AC Delco, don't put some fancy Bosch Platinum +4 in the car. Whether it's a Mercedes or a Mitsubishi, sticking with what it came with originally is the safest way to go. Doing otherwise can sometimes make the car run better, but often is a recipe for misfires.
After doing some research on my car I found out that it came with NGK plugs stock. A bit of googling later, and I had found everything I needed (cap, rotor, plug wires, spark plugs) for a general tune-up.
http://www.ngksparkplugs.com/images/IridiumIXwithLeaderLines.jpg
The NGK Iridium IX is one of NGK's newest designs, employing a 0.6mm iridium center electrode. Most publications indicate that this is good for 60,000-100,000 miles (SAE iridium technical paper (http://www.sparkplugs.com/pdfs/iri.pdf)). I had briefly considered going with NipponDenso and their 0.4mm iridium plugs, but the added performance comes with a corresponding drop in durability. Mind you, the Denso Iridium will still outlast most Platinum plugs, nevermind a conventional Copper or Nickel design.
After some careful use of dielectric grease/antiseize, I started up the car and went on my way. First impressions: slightly smoother idle, noticeably smooth acceleration. Granted, the old plugs were pretty worn (roughly twice the spec'ed air gap before a temporary regapping) but it still felt nice.
Periodical replacement of the spark plugs is essential to prevent costly repairs down the road. Not keeping up with scheduled maintenance intervals can and often does produce a chain reaction of events. Example:
Your modern, DIS-equipped car won't start one day, so you have to tow it to the shop and service it. Turns out the ignition module is bad. No big deal, they're bound to go bad anyway. So you replace it and go along your merry way. Except that this isn't an archaic points type where the lobe grinds away at the plastic actuating piece. Your car doesn't have a distributor cap accumulating deposits over time and building up resistance. It just uses an ignition module, which in turn uses transistors to complete the circuit to ground. These suckers are pretty damn reliable. Isn't replacing one of them without further diagnosing kind of like replacing a burnt-out fuse without finding out what caused it to burn out?
Lo and behold, the new ignition module lasts a year before crapping out on you. Now you're scratching your head and you begin fuming as it hits you - that damn thing was replaced no more than a year ago!
Ignition modules can burn out just from exposure to underhood temperatures, but chances are the OEM knew about that and shielded the module sufficiently. More likely, an unacceptably high amount of current flow through the module caused by a short fried the transistors. What can cause this?
Well, when the module grounds the negative side, current from the coils passes through it. The worst enemy of an ignition coil is heat. If the coil gets hot enough, the thin winding inside said coil can melt and short together, creating a easier path to ground and thus zapping the module with way more current than it is rated to handle. The module won't be able to take this for long before giving up the ghost, possibly leaving you stranded on the side of the road - with virtually no prior warning that it's getting cooked by excessive current flow.
What usually causes a coil to overheat? Too much voltage passing through it! In the old days of points and even with the newer systems, too long of a dwell period can energizing the coil for too long and heat it up real quick. Modern computer controls do a good job of controlling dwell though. Something much more simple, like a worn-out spark plug can easily do it. What happens is that as the plug wears, the air gap slowly but surely increases over time. As this air gap increases, the amount of required voltage to jump the gap increases. When the coil is forced to provide this higher voltage it heats up beyond normal operating temperatures. This can only continue for so long before something has to give.
Now what? Well, a coil can start from between $25 - $50 each. The module costs at least $250, probably more if you drive one of them fancy imported luxury cars or flashy sports cars. :P And the spark plugs that started this whole chain of events will set you back about $50. Given about 1-2 hours of book time labor to replace everything at between $95 - $105 per hour on average, and you just set yourself back more than $500 bucks (conservative estimate ;) ). Some basic tools, antiseize, and your own purchased spark plugs wouldn't have cost you even $100, probably under $75. BTW, that estimate of 500 bucks doesn't include the first time you replaced the ignition module.
Don't skimp out on a scheduled tune-up! You may be able to stretch it out somewhat beyond what is *ideal*, but all you really end up doing is playing with fire - eventually, you're gonna get burned.
http://akimages.crossmediaservices.com/dyn_li/200.0.88.0/Retailers/AdvanceAutoParts/ngk_iridium_spark_plugs.jpg