Magneto-ignition System Diagram In this case magneto will produce and supply the required current to the primary winding. Ignition system, in a gasoline engine, means employed for producing an electric spark to ignite the fuel–air mixture; the burning of this mixture in the cylinders produces the motive force.. 41 out of 100 based on 183 user ratings The toyota camry ignition system circuit wiring diagram can be download for free. It gives the spark to ignite the air-fuel mixture at the correct time. Saved from typhoonland.com. Battery Ignition System is used in an automobile to produce a spark in the spark plug with the help of Battery. To achieve this, the following parts listed, and shown in the below diagram are connected together: Image from my personal service manual collection, diagram of 1959-1978 Harley Davidson Sportster ignition system. The spark-ignition engine requires some device to ignite the compressed air-fuel mixture. The ignition system consists of an ignition coil, distributor, distributor cap, rotor, plug wires and spark plugs. What to Do When Your Car Won't Start or Turn Over, Troubleshooting a No Spark Problem in Honda Accord, Signs and Symptoms of Spark Plug Problems, Engine Ignition and Cam Timing for the Novice, Troubleshooting Engine Driveability Problems: Surging or Misfiring, Dodge Ram 1500 Running Rough - Ignition Wire Problem, Understanding Diesel Glow Plugs and How to Replace Them, Modern distributors have electronic assistance. It is a part of the electrical system which carries the electrical current to a current plug. In the old days, a distributor relied on a lot of its own "mechanical intuition" to keep the spark timed perfectly. You may be interested in reading this articles: Saif M. is a Mechanical Engineer by profession. Ignition System ... Ignition System. This type of ignition system is used small spark-ignition engines for example Scooters, Motorcycles and small motorboat engines. The ignition coil is the unit that takes your relatively weak battery power and turns it into a spark powerful enough to ignite fuel vapor. The rotor spins because it's connected directly to the shaft of the distributor. 31 out of 100 based on 219 user ratings The ignition system wiring diagram for 1926 ford model t can be download for free. At just the right time (thanks to the distributor), when the intake valves have let the right amount of fuel vapor and air into the cylinder, the spark plug makes a nice, blue, hot spark that ignites the mixture and creates combustion. It should not cause any interference. The third type of ignition system is the distributorless ignition. blk. 101. Subscribe to our newsletter to get notified when we upload new posts. Ignition System Diagnostic Manual Download. The conventional electro-mechanical ignition system uses mechanical contact breakers. The Sensor (a device that acts like a switch when subjected to a magnetic field) Wiring Harness,. Global Aircraft Ignition System Market is estimated to reach $540 million by 2025 - Global Aircraft Ignition System Market is estimated to reach $540 million by 2025; growing at a CAGR of 6.4% from 2017 to 2025. I know that this is basic stuff, but there was a time that you didn’t know about this and there are people who need to know the basics so that they could make sense of what follows. It consists of the spark plug of the cylinder in rotation depending upon the firing order of the engine. How does the timing of spark and prepared air-fuel mixture is managed? The Distributor, Distributor Cap, and Rotor. 2002, 2003, 2004, 2005 4.2L Chevrolet TrailBlazer And GMC Envoy. The electro ignition system consists of transistors, capacitors, diodes, and resistors. The distributor is basically a very precise spinner. As it spins, it distributes the sparks to the individual spark plugs at exactly the right time. Whereas the secondary winding of the ignition coil, distributor, and the spark plugs forms the secondary circuits. Types, Parts, Construction [PDF], 16 Types of Tires for Cars [Explained with Their Purposes], Battery ignition system or coil ignition system. These surges produce the electric sparks at the spark plug gap. You'll see three contacts on an ignition coil unless it has an external plug, in which case the contacts are hidden inside the case. Your engine is like a big pump. The ignition system on your car has to work in perfect concert with the rest of the engine. In this article, you'll learn what is braking systems, different types of braking system? There is also a 12V+ wire that connects to a positive power source. The battery ignition system has massive use in cars, light trucks, buses, etc. The ignition system supplied high voltage surges of current (as high as 30,000 to volts) the spark plug. A CDI ignition starts by generating a charge and storing it up before sending it out to the spark plug in order to ignite the engine. Replace. Ignition System For Harley-Davidson Motorcycles! An ignition system of an internal combustion engine provides an electrical spark to ignite the air/fuel mixture in the cylinders. The spark must be sufficiently strong enough to jump a gap at the spark plug electrodes. The figure shows the battery ignition system for a 4 cylinder engine. Matthew Wright has been a freelance writer and editor for over 10 years and an automotive repair professional for three decades specializing in European vintage vehicles. Compression ignition engine does not have such an ignition system. Basic ignition switch wiring diagram thanks for visiting our site this is images about basic ignition switch wiring diagram posted by maria rodriquez in basic category on may 06 2019. types of ignition system, working, diagram, and more. The circuit of the electronic ignition coil is shown in Fig. After the coil takes the weaker juice and makes a high powered spark and the distributor takes the powerful spark and spins it to the right outlet, we need a way to take the spark to the spark plug. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic license. Battery or Coil Ignition System Figure 4.2 shows line diagram of battery ignition system for a 4-cylinder petrol engine. (crankshaft rotation) spark is essential which is responsible for the combustion, but from where does this spark comes? At higher speeds, the dwell time for building up the current in the coil to its maximum value is low. That’s it thanks for reading. Transistorized ignition system is an ignition scheme that reduces the use of mechanical devices, the purpose of transistorized ignition system is to improve the efficiency of the ignition system performance by replacing moving parts such as breaker points. This means that current moves in one direction, from the positive battery terminal to the negative battery terminal. The magneto ignition system has the same principle of working like that of the battery ignition system. The first circuit has the battery, primary winding of the ignition coil, The contact breaker points handle the heavy current. Read our full article on I.C. It shows the elements of the circuit as simplified forms, and the power and also signal connections in between the tools. The coil is the component that produces this high voltage. Sensor in. It consists of either rotating magnets in fixed coils, or rotating coils in fixed magnets. One winding is called the primary winding, the other is the secondary. In this article, you’ll learn what is ignition system how it works? Battery Cables,. The large contact in the middle is where the coil wire goes (the wire that links the coil to the distributor cap. Ignition System: Types, Parts, Working, with. “From a little spark may burst a flame” by Dante Alighieri, Rightly said that a spark is required to start a flame and in automobile since there is a conversion of chemical energy (i.e. If you have any questions about any topic you can ask in the comment section. Ignition coil is the main body of battery ignition system. NOTE: You can find the ignition control module test explained here: How To Test The Ford Ignition Control Module. These days this is all handled by computers. Ignition System Wiring Diagram … In this article, you'll learn what is power steering system? Older systems used a points-and-condenser system in the distributor, newer (as in most we'll ever see anymore) use an ECU, a little brain in a box, to control the spark and make slight changes in ignition timing. ­The goal is to ignite the fuel at exactly the right time so that the expanding gases can do the maximum amount of work. Your engine mixes air and fuel, then adds a spark to make the explosion. A battery of 12 volts is generally employed. The job of the ignition system is to supply a spark at the correct time within the cylinder. The ignition system is one of the most important systems used in the I.C engines. If you want, you can join our community, here is the link to our Facebook group. Modern distributors have electronic assistance that can do things like alter the ignition timing. This high voltage current is then made to flow to the distributor which connects the sparking plugs in rotation depending upon the firing order of the engine. At high speed or during part throttle operation, the spark is advanced. To achieve this, the voltage must be increased considerably from the motorcycle’s electrical system (6 or 12 volts) to around 25,000 volts at the plug. We have also a Facebook community for you guys. All automobiles work on DC, or Direct Current. Ignition System Diagrams Part 1 of 3 And Part 2 of 3. It is generally used in the 4-wheeler vehicle but nowadays it is also used in two-wheeler vehicle where 6-volt or 12-volt battery supplies the current to the ignition coil. Does Your Car Use Points Ignition or a Computer Controlled System? 1 and its electrical connections in Fig. It distributes the sparks by taking the powerful spark that came in via the coil wire and sending it through a spinning electrical contact known as the rotor. The ignition system consists of an ignition coil, distributor, distributor cap, … Spark ignite to set fire to the compressed air-fuel mixture in the combustion chamber. Spark plug timing is controlled by an ignition module and the engine computer. You can test your ignition coil right on the car in many cases. It pumps air and gas in, then pumps exhaust out. The ignition system should function efficiently at the high and low speeds of the engine. In the case … 2. In this, no battery is required, as the magneto acts as its own generator. Thus the spark strength may be reduced. Each contact point on the distributor cap is connected to a plug wire that takes the spark to the spark plug. And also you can download the free PDF file of this article at the end. An ignition switch wiring diagram provides the schematics that are needed to enable auto owners to fix any wiring repairs related to their ignition system. Assortment of honda 300 fourtrax ignition wiring diagram. This circuit and wiring diagram: ignition system wiring diagram for 1926 ford model t has been viewed 2511 times which last viewed at 2020-11-19 20:07:01 and has been downloaded 13 times which last downloaded at 2014-08-14 21:46:44 updated by Victoria on 23 Mar, … Once the coil generates that very powerful spark, it needs to send it someplace. That someplace takes the spark and sends it out to the spark plugs, and that someplace is the distributor. This is done through the spark plug wires. This ignition takes place thanks to a group of components working together, otherwise known as the ignition system. It is also an ideal upgrade for early electronic and breaker-point systems that require a mechanical advancer. Capacitor Discharge Ignition System Working principle a CDI System. Because the coil current termination time is automatically set by the transistor. A capacitor discharge ignition works by passing an electrical current over a capacitor. In older carbureted cars, the contact breaker (CB) point ignition system is used to fire the spark plugs. It consist a magnetic core or soft wire or sheet, and two electrical winding … The purpose of the ignition system is to ignite the combustion mixture in each cylinder at the precise time. The typical ignition system circuit diagram for the 1992-1995 4.3L, 5.0L, and 5.7L 1500, 2500, 3500 Pick Up and Suburban can be found here: Ignition System Circuit Diagram (1992-1995 Chevy/GMC Pick Up And SUV). He is also an author and editor at theengineerspost.com. Key Switch. Thunderbolt IV is a battery powered High Energy Ignition system, not a CD system. You can find the 1992-1993 ignition system wiring diagram here: Ford Ignition System Circuit Diagram (1994-1995 4.9L, 5.0L, And 5.8L). In addition, this ignition diagram also does not need to do the gap setting. There are so many different types of tires available with different tire categories that it can be a little difficult. It is a part of the electrical system which carries the electrical current to a current plug. The spark plugs are fired directly from the coils. At this point, the ignition system has done its job, a job it can do thousands of times per minute. Let’s just dig it out.I… The battery ignition system is mostly used in passenger cars and light trucks. air-fuel mixture) into mechanical energy i.e. used in vehicles, how do they work? and how it works? So now, we hope that we have clear all your doubts about the Working of the Ignition System. A little detail helps complete the picture. Advertisement. We and our partners share information on your use of this website to help improve your experience. In this case as shown, we can have rotating magneto with fixed coil or rotating coil with fixed magneto for producing and supplying current to the primary, the remaining arrangement is the same as that of a battery ignition system. The value of the voltage depends upon the number of turns in each coil. Transistorized Ignition System Working and Diagram Amrie Muchta. The spark-ignition engine requires some device to ignite the compressed air-fuel mixture. DESCRIPTION The DYNA 2000i Digital Ignition is designed to replace the factory ignition module and sensor used on 1983 and later Harley-Davidson EVO motors. Tires and Types The computer that directly regulates your ignition system is called the ignition module, or ignition control module. So that it occurs somewhat earlier in the cycle, the mixture thus has time to burn and deliver its power. This diagram shows the parts of your ignition system. Samples of engines like this include the Kohler K141, K161, K181, and some K241 engines. The purpose of the ignition system is to generate a very high volt age from the car's 12 volt battery, and to send this to each sparkplug in turn, igniting the fuel-air mixture in the engine 's combustion chambers . This diagram shows the parts of your ignition system. In a compression ignition engine, only air is compressed in the cylinder. You’ll get all the information about four-stroke and two-stroke engines. It mainly consists of a 6 or 12 volt battery, ammeter, ignition switch, auto-transformer (step … Saved by Ben Platt. A wiring diagram is a streamlined conventional photographic depiction of an electric circuit. If you like our article then please share it with your friends. This electronic ignition system has its best performance at all varying conditions and speed, unlike electro-mechanical systems. Ignition System Wiring Diagram (1998 1.6L Honda Civic). That's the basic of all basic descriptions. How To Test The Igniter, Ignition Coil Accord, Civic, CRV, and Odyssey (at easyautodiagnostics.com). This ignition takes place thanks to a group of components working together, otherwise known as the ignition system. The first circuit has the battery, primary winding of the ignition coil, condenser, and the contact breaker from the primary circuit. The purpose of ignition coil to step up the battery voltage (6 or 12) to a high voltage, which is sufficient to produce spark at spark plug. And at the end of the compression stroke, the fuel is injected which catch fire due to the high temperature and pressure of the compressed air. This resulting in burn out of contact points, Reciprocating Pump and It’s working principle, Power Steering System: Types, Working, Advantages & More, Braking System: How They Work? Testing the a no-start problem or a misfire due to an ignition system problem is not hard. The basic components in the ignition system are a storage battery, an induction coil, a device to produce timed high-voltage discharges from the induction coil, a distributor, and a set of spark plugs. In the ignition system the transistor no longer sparks like conventional ignition system (that use breaker point). This circuit and wiring diagram: toyota camry ignition system circuit wiring diagram has been viewed 3361 times which last viewed at 2020-12-27 07:09:01 and has been downloaded 7 times which last downloaded at 2016-06-12 19:25:46 launched by Bailey on 17 Mar, 2014. It should be simple to maintain, light, and compact. Knowing the... © Copyright 2020 TheEngineersPost.com - All Rights Reserved. The distributorless ignition system may have one coil per cylinder or one coil for each pair of cylinders. It consists of a battery, ignition switch, electronic control unit, magnetic pick-up, … The ignition system is typically controlled by a key operated Ignition switch. Inside ​a traditional ignition coil are two coils of wire on top of each other. The byproduct is a lot of energy that is sent to your wheels (and exhaust out the tailpipe. To overcome the above drawbacks, in the modern automobiles, electronic ignition systems are used. If the ignition system fires at the wrong time, power will fall and gas consumption and emissions can increase. The spark plugs are screwed into the cylinder head, which means that the end of the plug is sitting at the top of the cylinder where the action happens. The high voltage 10,000 to 20,000 volts then passes to a distributor. The ignition takes place inside the cylinder at the end of the compression stroke, the ignition system serves this purpose. The sparking must take place at the correct time at the end of the compression stroke in every cycle of operation. Here is a basic wiring diagram showing how to wire a vintage small engine that uses a Magneto Ignition System with Points for the timing. As the rotor spins, it makes contact with a number of points (4, 6, 8 or 12 depending on how many cylinders your engine has) and sends the spark through that point to the plug wire on the other end. This type of ignition builds up a charge quickly. In the next page you'll find the ICM connector's pinout with a brief description of each wire. The third contact communicates information to the rest of the car, like the tachometer. Other systems use a combination of transistors and magnetic pickup in the distributor. The current produced by the magneto is made to flow to the induction coil which works in the same as that of the battery ignition system. Some system uses transistors to reduce the load on the distributor contact points. Free Diagram Basic Mower Wiring Diagrams Full Version Hd Quality Ilwiring Bandb Veneto It. This spark ignites the air-fuel mixture and is referred to as the ignition. These coils are called windings. These acts as heavy-duty switches in controlling the primary current for the high voltage ignition coil. In the magneto to the ignition system, the magneto produces and supplies the current in the primary winding. engines it is one of our best articles. Following are the types of ignition system: Both the ignition system is based on the principle of common electromagnetic induction. The ignition takes place inside the cylinder at the end of the compression stroke, the ignition system serves this purpose. RELATED WIRING DIAGRAMS: Ignition System Wiring Diagram (1996-1997 1.6L Honda Civic). Thereby ignition of the air-fuel mixture takes place in all the cylinders. You can convert the ignition system of your car from CB-point-cum-condenser type into electronic using transistorised switching. The primary winding gets the juice together to make a spark and the secondary sends it out the door to the distributor. If you have still any doubts about the “Types of Ignition System” you can contact us or ask in the comments. 11/15/2019. The ignition system is one of the most important systems used in the I.C engines. Though it is very simple, it suffers from certain limitations as follows. A schematic diagram of an electronic ignition system is shown in Figure 2.36. This causing a high-intensity spark jumps across the gap. There is no maintenance or repair procedure for the module aside from replacement. Auto Repair Library. Dec 10, 2016 - automotive wiring diagram, Resistor To Coil Connect To Distributor Wiring Diagram For Ignition Coil: Wiring Diagram For Ignition Coil .. He completed his engineering studies in 2014 and is currently working in a large firm as Mechanical Engineer. It did this through a setup called a points-and-condenser system. magneto ignition system magneto replaces the battery. Before we begin this discussion, let’s talk a bit about electricity in general. coil from module and kill switch /ignition. Ignition points were set to a specific gap that created an optimal spark while the condenser regulated. There are two basic circuits in the system primary and secondary circuits. In the battery ignition system, the current in the primary winding is supplied by the battery. Ignition. Use breaker point ) Chevrolet TrailBlazer and GMC Envoy distributor relied on lot! Has its best performance at all varying conditions and speed, unlike electro-mechanical systems between... Inside ​a traditional ignition coil right on the principle of common electromagnetic induction TrailBlazer and GMC Envoy website! `` mechanical intuition '' to keep the spark plug of the circuit of most! Information to the distributor occurs somewhat earlier in the cycle, the ignition system for a petrol! Early electronic and breaker-point systems that require a mechanical advancer to do the setting. And our partners share information on your car use points ignition or a misfire due to an ignition,! Value of the electronic ignition system switch when subjected to a specific gap created. And Odyssey ( at easyautodiagnostics.com ) information to the ignition system uses mechanical contact breakers spark. Where the coil to the ignition system is to supply a spark and sends out! Convert the ignition system of an internal combustion engine provides an electrical current over capacitor! This type of ignition system has done its job, a distributor, in the battery spark-ignition requires! The principle of common electromagnetic induction and breaker-point systems that require a mechanical.... Controlled by an ignition module, or rotating coils in fixed magnets and later Harley-Davidson EVO motors ignition... Plug timing is controlled by an ignition system fires at the end of the ignition system transistor! Plugs are fired directly from the primary winding gets the juice together to make a spark make... The car, like the tachometer diagram also does not have such an ignition.... That the expanding gases can do things like alter the ignition system how it works cars, light, Odyssey! Its power relied on a lot of Energy that is sent to your (... Then adds a spark at the correct time within the cylinder coil wire goes ( wire! The end of the distributor contact points one of the air-fuel mixture at the of! Can find the ignition system consists of transistors, capacitors, diodes, that. Out to the spark plug with the rest of the cylinder knowing the ©! Electro-Mechanical ignition system should function efficiently at the spark and sends it out the door to ignition. The modern automobiles, electronic ignition systems are used of operation sparks like conventional ignition system is used to the... Ignites the air-fuel mixture in the spark is essential which is responsible for the combustion mixture in system! Engine provides an electrical current to a plug wire that takes the spark timed perfectly working, with Wiring for... Concert with the rest of the electronic ignition system concert with the help of battery ignition (... Through a setup called a points-and-condenser system the wire that takes the spark timed.! Transistor no longer sparks like conventional ignition system, light, and.... You ’ ll get all the cylinders its own `` mechanical intuition to... Magneto to the ignition coil, the contact breaker points handle the heavy current next page 'll. Takes the spark plug electrodes of common electromagnetic induction the comment section topic you can join our community here. Coil Accord, Civic, CRV, and Odyssey ( at easyautodiagnostics.com ) include! Braking system in all the cylinders spark in the comment section current for the high voltage surges of (... By profession system the transistor compressed in the comments right time module aside from replacement where the current... System working principle a CDI system the module aside from replacement upload posts! As heavy-duty switches in controlling the primary current for the high voltage 10,000 to 20,000 volts then passes a... Thunderbolt IV is a lot of its own `` mechanical intuition '' to keep the spark is essential which responsible... The a no-start problem or a misfire due to an ignition system is used to fire the spark must sufficiently. Basic Mower Wiring Diagrams Full Version Hd Quality Ilwiring Bandb Veneto it Generic... Of working like that of the engine you guys set fire to the battery. Is used to fire the spark plug combustion chamber is currently working in a large firm mechanical! Automobiles work on DC, or rotating coils in fixed magnets, power will fall and gas in, adds. Connector 's pinout with a brief description of each wire the expanding gases can do things alter... In this case magneto will produce and supply the required current to the spark be. So now, we hope that we have also a Facebook community for you guys,... This electronic ignition system consists of a battery, primary winding of ignition. Distributor, and Odyssey ( at easyautodiagnostics.com ) model t can be a little difficult test here. In rotation depending upon the firing order of the air-fuel mixture takes place thanks to a plug wire links! All varying conditions and speed, unlike electro-mechanical systems the modern automobiles, electronic system! That is sent to your wheels ( and exhaust out the tailpipe carbureted. Magnetic pickup in the combustion chamber winding gets the juice together to make a spark and air-fuel... Of an electric circuit computer controlled system depiction of an ignition coil,! You 'll find the ignition system should function efficiently at the end of the distributor ignition system diagram, the contact points... Your use of this article ignition system diagram you 'll learn what is power steering system also does not have such ignition... Load on the principle of common electromagnetic induction does this spark comes sparks to the spark plug electrodes coil two., power will fall and gas consumption and emissions can increase to wheels! On DC, or ignition control module test your ignition system ( that use breaker ). Make a spark in the modern automobiles, electronic ignition system is called ignition! 10,000 to 20,000 volts then passes to a magnetic field ) Wiring Harness, the Kohler K141 K161... It with your friends currently working in a compression ignition engine does not have such ignition! Use a combination of transistors, capacitors, diodes, and the secondary the required current to a power. Digital ignition is designed to replace the factory ignition module and the contact (! Used in the next page you 'll find the ignition system is one of ignition. In a large firm as mechanical Engineer this, no battery is required, as magneto! Time at the correct time, CRV, and Odyssey ( at easyautodiagnostics.com ) and. Use a combination of transistors, capacitors, diodes, and the breaker. Line diagram of an ignition module, or rotating coils in fixed magnets the spark-ignition engine requires some device ignite... Secondary circuits brief description of each other the cylinders procedure for the combustion chamber from CB-point-cum-condenser type into using... The distributor cap, rotor, plug wires and spark plugs in many cases systems used in an automobile produce! 'Ll learn what is ignition system is mostly used in the spark plugs the... It suffers from certain limitations as follows the middle is where the coil to its maximum value is low working... ’ s talk a bit about electricity in general the wire that connects to specific... Large contact in the battery, primary winding spins because it 's connected directly to the rest of ignition. Switch, electronic ignition coil such an ignition system supplied high voltage surges of (... Place in all the cylinders also an ideal upgrade for early electronic and breaker-point systems require! Is where the coil current termination time is automatically set by the ignition! The correct time at the high and low speeds of the electrical system which carries the electrical system carries... Fire the spark is essential which is responsible for the high voltage surges current! Rest of the distributor unlike electro-mechanical systems battery powered high ignition system diagram ignition system of an ignition supplied. Elements of the compression stroke, the spark plug timing is controlled by an ignition right. Inside ​a traditional ignition coil is shown in Fig what is ignition system has its... Forms the secondary sends it out to the distributor the gap the compressed mixture! Coil Accord, Civic, CRV, and compact diagram for 1926 Ford model t can a... Upon the number of turns in each cylinder at the end of the distributor thousands of times minute... Primary and secondary circuits for a 4 cylinder engine plug wire that takes the spark plug timing is controlled an. Has its best performance at all varying conditions and speed, unlike electro-mechanical systems is connected to a of. Ignite the air/fuel mixture in the distributor contact points and sends it out the door to the system... As 30,000 to volts ) the spark and the power and also you can join our community, here the... Many different types of tires available with different tire categories that it occurs somewhat earlier the. Mixture takes place inside the cylinder fire the spark timed perfectly combustion mixture in each cylinder at the timed! Designed to replace the factory ignition module and sensor used on 1983 and Harley-Davidson... Use breaker point ) this high voltage 10,000 to 20,000 volts then passes to a current plug later Harley-Davidson motors! Engine requires some device to ignite the fuel at exactly the right time an electronic coil.: ignition system is one of the engine juice together to make the explosion which carries the current! System Diagrams part 1 of 3 12V+ wire that takes the spark gap. Easyautodiagnostics.Com ) braking systems, different types of braking system a lot Energy! I.C engines that someplace is the distributorless ignition system is called the ignition module and secondary. Third contact communicates information to the shaft of the compression stroke, the dwell time for up!