TEMEA research project ensures quality of electronic components in the automotive industry

Under the leadership of Fraunhofer FOKUS and with financial support from the Investitions­bank Berlin, the TEMEA project – Test Specification Technology and Methodology for Embedded Real Time Systems in the Automobile – has now taken up its work.

The main aims of the TEMEA project are to meet current and future demands for Quality Assurance in the automotive industry through the development and provision of standardizable testing technologies, and also to substantially lower production costs. Alongside the Fraunhofer Institutes FOKUS and FIRST, the other project partners include IT Power Consultants, Testing Technologies IST GmbH, Fourth Project Consulting and the University of Göttingen.


The project will run for three years; first results are expected in fall 2008.

“In spite of intensive efforts on the part of automobile manufacturers and their suppliers, no solutions have yet been found for dealing with problems arising from the testing and Quality Control of increasingly complex, increasingly networked systems,” says Prof. Dr. Ina Schieferdecker, TEMEA project manager at the Fraunhofer Institute FOKUS, talking about the project background. “For instance, test specifications for test systems and test solutions – many of which are proprietary – cannot be reused – neither between the original equipment manufacturer and supplier nor on a cross-project basis within the company. This leads to an unnecessarily high workload in terms of test specification and implementation, inhibits communication between producer and supplier and prevents reuse of existing test artifacts. The bottom line is that the quality of the whole vehicle suffers.”

The approach adopted by the TEMEA project is specially tailored to meet requirements-driven systematic testing of electronic components and their integration in the automobile. Based on the standardized testing technology TTCN-3, the TEMEA project seeks to develop a uniform test specification technology consisting of textual and graphical means of description for test specification, a flexibly adaptable test implementation and runtime environment, and a configured testing methodology that will satisfy the needs of suppliers and major manufacturers alike. An approach of this kind – which promises to raise the efficiency of Quality Assurance processes for software-intensive systems through standardizable technology and thus to lower their production costs – is something completely new for the automotive industry. A further special feature of the project is that it also covers current automotive industry standards such as AUTOSAR. The main project areas are

• integrated testing of discreet and continuous behavior,
• cross-platform exchange of test definitions (MiL/SiL/HiL),
• support across the whole testing and integration cycle,
• analysis of real-time and reliability requirements,
• testing of AUTOSAR components, and analysis of test quality.

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Other than as a source of light, rays of light radiated from the car also became alert to other vehicles. However, if the condition is less good, when the rainy season can arise in the dew light car.

If you want to turn, reduce speed or stop, for example, a rider or winking light rays as a means to communicate with other vehicles. For that, the lamps shining car should be light. Do not dimmed a bit, especially out at all.

One cause of the light rays can interfere with the car is moisture. Although only a vapor, the moisture to sneak in the lamp can be with the car.

Besides dim ray emission from the bulb, dew or moisture can cause the bulbs drop out, especially if moisture or water vapor to the cables to trigger short circuit time dialiri electricity.

Therefore, try to check the lamp of your car. If there is dew or moisture in it, most likely mica and spools in conditions that are less good. While handling, with the gracious light cover, and to dry clean using a rag and spray with the air compressor or hair dryer (hair dryer).

For a more satisfactory results, we recommend to replace the mica and seals in car lamps with its a new. Seal less, in general meeting occurred because of the age.

The older age of the vehicle, the seal is generally less elastic (hard). Moreover, if the vehicle is often parked in the summer. The mica is so, the old age of the vehicle and the more often exposed to hot temperatures, the possibility of cracked or broken the greater.

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Introduction

Carburettors were used until 80's on Spark Ignition (SI) engines to provide mixture of air and fuel. But their weakness were the inaccurate metering of the fuel quantity and the bad vaporization of it. Due to air pollution control and fuel efficiency, a solution had to be found. Injection system were introduced in the 80's. The first systems were mechanically driven. The pressurized injection provided a better vaporization of the fuel and thus a more homogeneous mixture which results in more efficiency. But the mechanical system had also his limitations and could not provide an accurate metering of the fuel on the whole engine working range. Electronic Fuel Injection (EFI) solved this problem by giving a more flexible metering.

This presentation will cover the design of the embedded control system used for the EFI. The history and deep going technical aspects of the carburation will not be discussed here.


Carburation basics

A SI engine works mostly with a stoichiometric mixture of air and fuel. The quantity of fuel is given as function of the quantity of air as the Air Fuel Ratio (AFR). Typically, for standard gasoline :

AFR = 14.7 / 1

The injected fuel quantity is thus proportional to the quantity of air which income in the engine's cylinder. So this mass of air can be used as parameter to calculate the requested fuel quantity.

As this relation is true for normal operating range, (e.g. : cruising) some corrections have to be made for other conditions like idling and full load or Wide Open Throttle (WOT).

The whole operating range of the engine can be determined by two parameters : Speed of the engine in Revolution Per Minute (RPM) and Manifold Absolute Pressure (MAP) which gives the load of the engine. As boundary conditions, we can retrieve the idling with low RPM and the WOT with high MAP.

The volumetric efficiency (VE) is the volume of air incoming in the engine divided by the engine's displacement. The VE quantify the filling of the engine with air and depends of the engine's state. A table of the VE can thus be made in function of the engine's speed and the MAP.

Knowing the VE, the mass of air can be found by the ideal gas law.

And so the requested fuel quantity is compute by multiplying mair by the AFR.

Deviations from the normal working conditions can then be added. These are the warm-up enrichment (choke) or the deviation from standard atmospheric pressure.

Now that the requested fuel quantity is computed, it is important to verify if the AFR is correct. That is why an Exhaust Gas Oxygen (EGO) sensor is used to do a closed loop regulation. This aspect will be discussed later.

Design Criteria

One of the most important criterion to design an embedded control system for application in automotive technology is the robustness.

The hardware has to be robust against the environment in which it will be used. In automotive applications, the temperature can go from -40°C to more than 100°C in some places of the engine compartment. Moreover, it has to resist to shocks and vibrations due to road and the dynamic of the car. This robustness also involves good quality. Most of the time, is an EFI system designed to work during the whole life of the car.

Another important aspect is the speed of the hardware. A SI engine rotate to minimum 6000 RPM. Which means 200 Hz injection sequence for a L4 engine. It is naturally quite slow comparing to the speed of an actual computer's CPU but all the operations to compute the requested fuel quantity have to be done 200 times per second which of course ask a greater clock speed.

The system also has to be robust against the failure. It must protect the engine against bad working conditions like too high speed or temperature. If something is going wrong, the system must shut down the engine and no let him accelerate for example.

The communication is also important. Most of the new cars use for example CAN-bus protocol for communication between different component. The vehicles are also equipped with On Board Diagnose system (OBD 2) which must be able to communicate with the Electronic Control Unit (ECU).

And last but not least the price must also be taken into account. A system must be as inexpensive as possible to have a chance to be used in production cars.

Hardware

The hardware can be divided in three components. The sensors, the ECU, and the actuators.

Sensors

The sensor used in this application provide all the necessary parameters to have the best view on the engine's situation and compute the requested fuel quantity. These are :

MAP sensor : Piezoresistive sensor Throttle Position Sensor (TPS) : rotational potentiometer Tachometer : this signal can be taken from the ignition coil or with a crank and a camshaft position sensor (variation in function of the car) Coolant and Air temperature sensor : NTC thermistor EGO sensor : wide band warm oxygen sensor (aka Lambda sensor)

Most of the sensor's output are varying between 0 and 5 V DC and give an analogue signal.

ECU

The most important part of the ECU is the processor. The choice of it must satisfy all the criteria mentioned above. For the example of the Megasquirt, the processor is a Motorola MC9S12C64 which is adequate for this kind of application. This processor was originally used in ABS ECU and works from -40°C to 125°C. This answers to the criterion of robustness against hostile environment. It has a 16 bits core which means accuracy in the computed values and 2K RAM which can handle more parameters (like ignition timing, Idle control, ..) 24 MHz speed which allows fuel control to 1 µs And a flash memory of 64K to keep the embedded code.

The Printed Circuit Board (PCB) have minimum 6 analogue port in for the sensors signal and 4 out for the injectors. It also has some spare ports for additional applications like ignition timing, ...

As the price must be competitive, the whole PCB cost about $85.

For OEM, the ECU does not have to be re burned or modified. So it is most of the time protected by silicon against vibrations.

Actuators

Actuators are here the injectors. They work with a piezoelectric actuator or solenoid which opens the injector under 12V voltage.

These are rated by the fuel flow they can deliver. This parameter is given in cc/Min @ full opening. The choice of injector is specific to each engine and it's application.

Once the requested fuel quantity is computed by the ECU, it can be easily converted in injector's opening time. This opening time theoretical equal to time that the injector must be feed with 12V or the pulse width. Deviations from the theory occurs due to the finite time needed to fully open the injector and the battery voltage variation. Those two facts must also be taken into account.

Injectors can be have low or high impedance. So in order to work with low impedance injectors, the current must limited. This can done by adding resistor or reducing the current electronically with a Pulse Width Modulation (PWM). If the injector is very quickly set alternatively to 12V and ground the total amount of current in the injector will decrease.

The PWM rate can thus regulate the current trough the injector.

Software

As said before OEM keep the software of EFI very secret. That is why only a few general characteristics will be given.

Because of the repetitive aspect of the system and the simplicity of the hardware, no Operating System (OS) is needed. For OEM, the software is burned on memory once for all.

The working principle is as follows :

The requested fuel quantity is computed with the VE table and the perfect gas law. Corrections are made in function of the temperature,atmospheric pressure,EGR,... The final fuel quantity is translated into a PW. The PW is translated to electric signal which is send to the injectors.

This part of the control system is a full feed forward regulation.

A closed loop regulation with EGO correction is added to the process. This regulation works only in normal working conditions (not idling or WOT). The ECU checks the value of the lambda sensor and adjust the fuel quantity. The burning process has a certain time constant. So the lambda value is not checked every time but for example every 7 ignition events. If the value returned by the EGO indicates that the mixture is rich, the fuel quantity will be lowered of one fixed incremental value and vice & versa.

The megasquirt system provide all the features above in the software but everything can be modified to suit a given application.

C programming language is used for the code and then complied to be burned on the ECU The software can be tuned by a user's interface which modify the C code before it be burned A serial port is used to read and write all the computed and measured values can be downloaded in a log file The code is open source

Conclusions

The EFI system provide a good example of how electronic can supply mechanic and how a simple embedded control system can be developed.

With the time the systems become more complex. They handle detonation control, idling,.... Like for the diesel engines the injection become also more and more accurate with a better control of the combustion.

EFI was originally the only electronic device in a car. But now, it is only a component of the system. Electronic found also place in steering, gearbox management, stability control, ... All this improvements mean a better system but can also give more failure due to the complexity.

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Pioneer AVH-P3100DVD 5.8-Inch In-Dash Double-DIN DVD Multimedia AV Receiver with Widescreen Display

Product Description

DVD/CD receiver with internal amp (14 watts RMS CEA-2006/50 peak x 4 channels) * 5.8" touchscreen * plays MP3/WMA/AAC files recorded on CD and DVD * compatible with Pioneer iPod adapter, Bluetooth adapter, satellite radio, HD Radio tuner, and CD changer *

Product Details

* Amazon Sales Rank: #177 in Consumer Electronics
* Brand: Pioneer
* Model: AVH-P3100DVD
* Dimensions: 3.60" h x 20.40" w x 12.00" l, 6.60 pounds

Features

* 5.8-inch motorized touchscreen LCD monitor
* Double DIN
* Plays DVD-R/RW, CD-R/RW, DivX, MP3, WMA and AAC
* Features touchscreen control for iPod/iPhone¿ with album art, touch slide, ASR and USB control
* 4V preout

Customer Reviews

Great Receiver for the Money!5
Just put this receiver in my 2004 F-150 not but 2 days ago. So far it has worked flawlessly. The DVD clarity is excellent, the sound quality is superb. The controls are very easy to use and you can customize the deck to fit your needs (i.e.: changing background colors, button colors, changing background image- 6 are preloaded). I bought the recommended ipod connector cord (Pioneer CD-IU50V) and it works great too. I hooked it up to my iPhone 3G, and iPod Video and they both work awesomely! All in all, this is a great buy for anyone looking for an aftermarket upgrade.

Great Receiver4
Purchased this item last week with the bluetooth adapter and had it professionally installed. The touch screen works well and the color customization is a must have for me since my car dash color is an off green. Sound quality is great, even with my dated factory speakers (plan to upgrade speakers later.) Bluetooth function works well with my iphone, sound quality crisp on both ends. However, I am having issues transferring my phonebook/contacts to the unit. I dont know if this is a compatibility issue or what. Overall, i would highly recommend this unit to anyone looking to upgrade, especially if hands free phone usage is important to you. I did not give this product a "five star" because in order to make calls using the touch screen, pioneer requires the car to be in park with the parking brake activated. The same with DVD video playback (which is the law). I bypassed this easily and you can too with a little research on how to. If you can get your phone book to transfer, voice dialing is an option. Hope this review is helpful.

Best car stereo I've owned5
The Pioneer AVH-P3100DVD is a touch-screen Double DIN aftermarket car stereo. It has a 5.8" full color widescreen face, front auxiliary port for connecting an Ipod or other device, a front USB port for connecting a USB flash drive, and it can play DVD-R/RW, CD-R/RW, DivX, MP3, WMA and AAC files. The Pioneer AVH-P4100DVD 7-Inch In-Dash Double-DIN DVD Multimedia AV Receiver with Widescreen Display is the same exact radio, except it adds a bigger screen (7") by removing the physical buttons to the side, and it adds a subwoofer preamp output.

INSTALLATION AND DVD BYPASS: Double DIN means that it is roughly twice the size of a conventional car stereo, so before ordering, you need to make sure it will fit in your car. The best way to do this is to go to Crutchfield's web site and determine if it will work on your vehicle. The unit itself comes with the receiver, mounting screws, manual, a stylus pen, front mounting cover, and a power cable. I found it fairly easy to install. The power cable it comes with just has bare wires coming out of it. In addition to the radio, you will want to buy a mounting harness and mounting bracket for your vehicle. The harness looks just like the one that comes with the stereo, but it is designed to clip into the factory harness that's in your vehicle, to make it easy to remove the stereo. If you don't have one, you'll have to connect all of the wires by hand, and disconnect each one to remove. The mounting bracket is designed to make sure you radio fits correctly in your specific vehicle. I purchased both the harness and bracket from Crutchfield. My only problem with installation, is that it comes with a long green wire that is supposed to be connected to your emergency brake wire. This is necessary, because the unit has a safety feature that requires the emergency brake to be applied in order to play DVDs. My emergency brake wire was extremely hard to get to, and once I was able to finally remove the center console and find it, it was buried and almost impossible to access. I don't suggest doing this, but if you have the same problem and want to get around this issue, or if you want to be able to watch DVDs without having to engage the brake, then you need to connect this wire to an auto relay switch. Go to Radio Shack and buy a momentary push button switch, part number 275-1548. Cut the green wire coming out of the radio harness from the receiver, close to the end of it, maybe 5 inches away from that red clip. Strip the wire, and run it through one of the holes on the relay switch. You can solder it or just wrap it with electrical tape. Buy a standard 16 gauge wire from Radio Shack and connect it to the other hole on the switch, then connect the other end of it to a grounded connection on your vehicle. I just wrapped mine around one of the mounting screws for the radio. I stuffed this wire out of site under the dash and pull it out when I need it. Alternatively, you can just cut the green wire directly in half, and use the half you cut instead of having to buy more wire at Radio Shack, but I wanted an extra long wire in case I ever want to move it. Now, when you play a DVD, the warning screen will come on. Just press the button on the switch and it will go away, since it tricks the receiver into thinking you have engaged the parking brake. Be sure to check with your local laws, as having the DVD player on while driving or bypassing this may be illegal in your area. It may also void insurance claims. I definitely do not recommend ever watching a DVD while driving.

FORM FACTOR: The radio itself is beautiful. It fit flush with my dash and looks gorgeous. There are only a few buttons on the left hand side, and I didn't even realize they were buttons until I looked at them closely. They control volume, forward/backward, source, mute, and power. I like having these physical buttons, especially for volume and mute. If I get a phone call or need to hear something, I want to be able to instantly mute the radio without having to fool around with a touchscreen. It's very nice to have a radio that doesn't have 15 buttons all over it and looks cluttered. Customization is easy with the radio. You can select from several different colors, which will change the LED colors on these physical buttons and on the touchscreen menu buttons, so that it matches your car's LED colors. You can also choose from seven factory background screens, three of which are animated videos. The animation on the videos is very subtle and doesn't distract you. Plus, when you change the LED color, it actually changes the color of the background videos to match it, which is really cool. If you don't like these, you can use your own image from a CDR or USB drive. The screen contains a dimmer option, so when you turn on your lights, it automatically dims. This is pretty nice, but can also be annoying. I like to use my lights during the day, and while the screen is still readable, it can be hard to see. Fortunately, you can completely adjust the dimmer options through the settings.

TOUCHSCREEN: The touchscreen is very easy to navigate and done very well. The menu system is very intuitive and set up a lot like a computer. There is a back button and an escape button to get you through the menus. Seeking through a song can be done in three ways. You can hold down the physical forward/backward buttons on the unit, you can do the same with the touchscreen forward/backward buttons, or you can use your finger to slide a progress bar back and forth, the same as you would do with a video file on your computer or with an Ipod. This is great because a 30 minute song can start, and I can just press the end of the progress bar with my finger and it will immediately skip to the end of the song (or whatever position I press on the bar). From what I can tell, it will scroll exactly like a computer and stop at the exact position you touch. A lot of touchscreens would have "segments" or 5-10 seconds, and stop on whichever segment you came close to. But with the AVH-P3100, it is segmented into 2 second increments, so you can have much more accurate scrolling. This is the only instance where I can see the stylus being of any use, but I have fairly large fingers and don't have any problem with the scroll bar. My main gripe with the touchscreen navigation, is with the up/down scrolling. This is used when navigating radio/satellite stations, song racks on a CD, or file folders on a USB/Ipod. There is no page up/down feature, so if five folders are displayed and you press the down arrow on the scroll bar, or if you press anywhere below the current position on the scroll bar, it will move the list down by one, instead of down by five. This is a major oversight in my opinion, and will affect the way you setup your folders. I have one folder on my USB with 80 subfolders. That means if I want to scroll through every folder in the list, I have to press the down button 75 times. Now you can put your finger on it and simply drag the arrow down to move quickly, but it goes kind of fast, and paging through the list would be so much more convenient. Also, since it only displays five lines at a time, it means you have to scroll one time to view all six of your radio presets.

USB/Ipod: Ipod menus look the same as the front of your regular Ipod and navigation is easy. It will also display a picture of the album. USB is the main reason I purchased this radio, and works well, with a few faults. First, it takes about 10 seconds when I start the car or select the USB source, for it to "read format." This is possibly because I am using a 8Gb drive with over 1000 songs on it, so it's acceptable to me. My main problem with the USB feature, is the way it organizes the folders. They do not appear alphabetically. I am not sure what method it uses, but like a lot of MP3 audio devices, it just seems to throw them up in the folder list in whatever order it wants. It will use the same order every time, but you can't trick it by copying a folder you want to appear at the top first, or adding "01, 02, 03, etc" in front of your folders/file names." There is probably a workaround for this, but I have no idea what it is. I think it would make more sense if it just listed the folders alphabetically. It does read ID3 information very well, however it cuts off anything after a certain character limit. It would be nice if it scrolled sideways through long song titles/artists to show you the full ID3 information, but for about 95% of people's music, this won't be a problem, and for the other 5% you should have enough of the title to figure out what it is. However if you don't have ID3 tags on your music, it can be a problem. For example, if you have a folder with 10 songs in it labeled "DJ Jazzy Jeff and the Fresh Prince - Greatest Hits - Girls Ain't Nothing But Trouble," and there are no ID3 tags, it is only going to display the first part of the filename until it reaches the character limit. So your list on the screen will have 10 songs on it that all say something like "DJ Jazzy Jeff and the Fr." Additionally, the USB drive is going to stick out 3" or so from the unit, so unless you remove it every time, you have to be aware of it and careful not to break it off. It doesn't bother me at all though. The only other problem I've noticed with the USB playback, is that the progress bar is off. The bar shows time elapsed and time remaining at the same time. Time remaining is incorrect about 80% of the time. A song will start up and it will show that it has 6:22 remaining, when it is only a 4:00 song. Some songs are accurate, but the majority is off anywhere from :30 to 3:00.

DVD PLAYBACK: DVD playback is superb. The video quality is on par with any portable DVD player you would buy. You cannot tilt the screen, so application is limited, but if you're parked somewhere you can easily enjoy a movie from any seat in the car. If it's daylight and sunny, you won't be able to see much however. The DVD onscreen menus are nice, and the scroll bar works well for skipping quickly through a movie, even better than a traditional DVD player. There's a HIDE button for quickly removing all onscreen displays, so you don't have to wait several seconds for the menus to time out.

SOUND: Sound quality is excellent. DVDs sound great. It has three loudness modes which really bring out the sound. I am using factory speakers with no amplifier, and the built-in Pioneer amplifier makes a huge difference. It has several pre-set equalizer settings for different types of music.

Overall, even if you don't get it at Amazon's current price (40% off SRP), I think this receiver is worth the money. It really is a beautiful and functional unit, and I always like showing it off to my passengers. It is too bad there doesn't seem to be a way to update the firmware, because it would be a perfect unit if Pioneer just made a few small changes to the menus. The unit also does not come with built in Bluetooth, HD Radio, Satellite, or steering wheel controls, but you can add all of these from the products below. I realize Pioneer makes more money by adding these separately, and also keeps costs down on the unit from not including them unless someone wants them, but it would be nice to have built in HD Radio and Bluetooth at least. Stay away from the remote though, it's worthless.

Pioneer CD-IU50V USB iPod Cable for Pioneer AVH-P3100DVD
Pioneer GEX-P10HD HD Radio Tuner for Pioneer HD Radio-Ready Head Units
Pioneer GEX-P920XM XM Satellite Tuner
Pioneer CD-SB10 - Sirius Bus Interface for use with Pioneer SAT Radio Ready Headunits and AV Receivers and SIRIUS SCC1 SIRIUS Connect Universal Tuner (you need BOTH of these to get Sirius radio)
Pioneer CD BTB200 - Cellular phone Bluetooth adapter
Pioneer ND-BC2 Universal Rear View Camera

» Read More...

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A spark plug initiates combustion in an internal combustion engine. A plug sits right inside the combustion chamber and can be removed for inspection. An examination, or "reading" of the characteristic markings on the firing end of the spark plug can indicate conditions within the running engine. A spark plug's firing end will be affected by the internal environment and will bear the marks as evidence of what is happening inside the engine while running. Usually there is no other way to know what is going on inside an engine running at peak power. The information obtained is especially important in high performance engines to refine the adjustment of all the systems.

The reading of spark plugs for a racing engine is a precision technique distinct from the more generic reading of spark plugs from general purpose engines, as the published information is intended for commercial mechanics to diagnose engine damage.

A racing engine is tuned whilst in prime condition. These engines require fine adjustment to much tighter tolerances. The most relevant spark plug parts for reading are at the tip, the center and side electrodes as well as part of the insulator.

Type the rest of your post here.
When a spark plug fires, it ignites the fuel-air mixture, creating a fireball inside the combustion chamber. The size of this fireball or 'kernel' depends on the exact composition of the mixture between the electrodes and the level of combustion chamber turbulence at the time of the spark. A small kernel will make the engine run as though the ignition timing was retarded. A large kernel appears like the timing was advanced for that individual cycle. The combustion process produces characteristic marks on the spark plug. It is these marks that you can analyse.
Contents
[hide]

* 1 Spark plug construction
* 2 Ignition process
* 3 Reading spark plug conditions
o 3.1 Accurate Reading Conditions
o 3.2 Gap Type
* 4 Engine conditions and impact on spark plugs
o 4.1 Heat range
o 4.2 Voltage loss
o 4.3 Ignition timing
o 4.4 Fuel mixture
o 4.5 Engine power
o 4.6 Ignition performance
o 4.7 Detonation
* 5 Other observable factors
* 6 External links

[edit] Spark plug construction

Image:Plug construction.jpg

* Ribs: The ribs prevent electrical energy from leaking from the terminal to the metal case along the side of the insulator. The longer the current has to travel because of the ripples the higher the resistance thereby assisting with isolation.

* Insulator: Made from Aluminum Oxide ceramic. Designed to withstand 1,200 deg. F. and 60,000 volts. The exact composition and length of the insulator, extending from the metal case into the combustion chamber partly determines the heat range of the plug.

* Metal Case: Bears the torque of tightening the plug. Removes heat from the insulator and passes it on to the engine head. It acts as the ground for the sparks passing through the center electrode to the side electrode.

* Center Electrode: Can be made of copper, nickel-iron or precious metals. The center electrode is designed to eject electrons because it is the hottest (normally) part of the plug. The electrons 'boil off' from the hot electrode. A further improvement would be to use a pointed electrode but a pointed electrode would melt after only a few seconds. The development of precious metal high temperature electrodes allows the use of a much smaller center electrodes that are smaller in diameter-closer to a point, but they do not melt or corrode away. A smaller electrode also absorbs less heat from the spark and initial flame energy.

* Side Electrode: The side electrode is made from high nickel steel and is welded to the side of the metal case. The side electrode also runs very hot, especially on projected nose plugs.

[edit] Ignition process

As the electrons are pushed in from the coil, a voltage difference appears between the center electrode and side electrode. No current can flow because the fuel and air in the gap is an insulator, but as the voltage rises further, it begins to change the structure of the gases between the electrodes.

Once there is a small channel of gas which is affected this way, it is said to be "ionized". An ionized gas becomes a conductor and can pass electrons.

As the current of electrons surges across the gap, it raises the temperature of the spark channel to 60,000 degrees K. The intense heat in the spark channel causes the ionized gas to expand very quickly, like a small explosion. This is the "click" you hear when watching a spark.

The heat and pressure force the gasses to react with each other and at the end of the spark event there should be a small ball of fire in the plug gap as the gasses burn on their own. The size of this fireball or kernel depends on the exact composition of the fuel-air mixture between the electrodes at the time of the spark. A small kernel will make the engine run as though the ignition timing was retarded and a large one like the timing was advanced for that individual cycle.

[edit] Reading spark plug conditions

Spark plug reading flashlight/magnifiers aid in reading spark plugs.
Two spark plug viewers

[edit] Accurate Reading Conditions

The most accurate plug readings are obtained after an engine is well tuned with new plugs and after shutting the engine at the end of a strong full throttle run. Having the engine shut down quickly and cleanly avoids creating misleading information and provides evidence from full power conditions. Idle conditions may be relevant for non-racing readings and general engine diagnosis.

[edit] Gap Type

Racers are concerned with only two gap styles illustrated in figure 2.

1. Projected Nose
2. Conventional gap

Most racing engines use projected nose, fine wire plugs, but some engines need the conventional gap fine wire plugs because of clearance problems or difficulty in cooling the plug. Surface gap, retracted gap, etc., plugs are not suitable for high performance use.

[edit] Engine conditions and impact on spark plugs

[edit] Heat range

With respect to heat range, manufactured racing engines already have most of the selection done. The stock plug is usually within two heat ranges of ideal. The only change that might be needed to use the fine wire version of the same plug (usually 1 or 2 steps hotter). For heavily modified standard engines the choice is less clear. A plug 2 to 3 ranges colder than stock and of the fine wire type would be a good starting point. Complete the ignition timing and fuel system adjustments first and then select the final heat range for the spark plug.

Figure 1 illustrates hot versus cold spark plugs. Spark plugs are capable of running anywhere from cold to hot in a given engine, depending on plug design. Use the hottest plug that won't over heat itself under the worst conditions.

A hot plug does not make an engine run hot, nor a cold plug make an engine run cold. A hot plug merely means that the insulator nose will run hotter and keep itself clean by burning off deposits.

A plug which is too cold collects carbon and fuel deposits on its insulator, which leaks energy from the ignition, causing loss of power, if allowed to continue it will foul (not spark at all).

The length of the insulator determines the heat range of a plug. Use the hottest plug that doesn't burn the tip of the center electrode.

If your plug is too cold, you will see deposits on the nose of your plug. Figure 6 illustrates this. If your plug is too hot, the porcelain will be porous looking, almost like sugar. The material which seals the center electrode to the insulator will boil out.

Note: A lower number usually means a colder spark plug but not all the time. Ex: NGK uses high numbers for cold spark plugs as Bosch uses a lower number for colder spark plugs.

[edit] Voltage loss

As the voltage builds up in the plug, it may leak to ground through any deposits, which are on the insulator nose, robbing the spark gap of its energy. This is what happens when you foul a plug. Any conductive deposits on the insulator nose will, (even if the engine doesn't misfire) cause a reduction of energy in the spark leading to small,erratic kernels, slightly reducing power.

[edit] Ignition timing

Ignition timing can be seen on the center electrode tip. If the timing is too advanced by 2 to 4 degrees, the tip of the electrode will be scorched clean for about one millimeter from the tip. The center electrode will have its edges rounded from heat. The material which seals the center electrode to the insulator may boil out. This is illustrated in figure 3.

When the timing is correct or retarded, the fuel deposits on the electrode tip will extend right to the tip. So you can only see ignition advance on the plug, not retard.

[edit] Fuel mixture

This is the most important part of plug reading and the most misunderstood. Mechanics are often talk about "color" on their plugs. However there is only one color to look for on a plug and that is black. It is soot, the remains of combustion.

The brown color you see on a plug is only the result of gasoline additives and nothing more. In an engine which is running well, the plug will run hot enough to burn off all the brown color, leaving only white and black. Under test conditions as there will be little time to accumulate fuel deposits.

The black will be found at the base of the electrode insulator nose where the porcelain meets the metal case. This is the only place on the plug where you can see if the engine is rich or lean. This carbon forms a ring around the base of the electrode very quickly. It can be seen after only a few seconds of full throttle running, but a couple of full throttle runs should be made so that the ring will be very clear. (See figure 4).

While learning to read plugs it will be much easier to see the mixture ring if you cut apart the spark plug and remove the porcelain from the metal case. (See figure 5.) You will see the mixture ring starting where the seal was and extending up the insulator some distance.

The optimum width of this ring is about 0 to 2mm millimeters with .5mm being ideal for many engines, more than this is too rich for most engines and many engines respond to a mixture where almost no ring is visible but you must conduct power tests to find the ideal for your situation. Make sure your heat range is correct because it may affect the mixture ring.

[edit] Engine power

Power produces heat and one can see the heat of combustion on the metal case of the plug. The only plugs that show this feature are the cadmium-electroplated types. Don't use the black oxide plugs because they can't show engine heat. Racing engines will produce enough heat to burn the plating off the end of the threads on the case as illustrated in figure 7. You should have 1 to 4 threads scorched by heat on your plugs. If you can't get that heat, you have a problem. Even if every other indication on the plug is perfect, the engine is not making its potential power.

[edit] Ignition performance

You can see the performance of your ignition system on the electrodes where the spark jumps from one to the other. The spark should burn clean a spot on both electrodes where the spark touches as illustrated in figure 8.

If the spot is small and irregularly shaped, your ignition is going bad. You should watch this spot when you are experimenting with spark plug gaps.

[edit] Detonation

"Detonation" is one of the worst things that can happen in a powerful engine because they are running near the edge of the envelope. It can occur for many reasons; high compression, overly advanced timing, fuel too low in octane rating, too high of a heat range spark plug or poorly shaped combustion chamber. It can often be seen on the spark plug before serious damage occurs.

You will see small balls of fuel and metal deposits on the porcelain tip and smaller balls of debris on the electrode tip. The metal case will look as if it were sandblasted (inside the engine the piston will also look sand blasted). See figure 9.

(Detonation is not entirely bad however, maximum power is always found with just a trace of detonation, not enough to be seen on the plug or to be heard by the driver, but enough to leave a slight sandblasted look (just enough to remove the carbon deposits) on the edge of the piston, after a race. (Drag racers may not have visible marks even though it is happening due to the short running time). It is theorized that the trace detonation is partially burning the otherwise unburnable mixture in crevices of the piston and chamber.) Image:plug_reading.jpg

[edit] Other observable factors

The information mentioned above is used in concert with other observable factors such as the operator's impressions, exhaust pipe deposits, combustion chamber and piston deposits, engine sound, actual measured performance of the engine, exhaust temperature and sometimes exhaust gas analysis.

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