VIDEO: How Much Energy Does It Take To Fire A Coil?

VIDEO: How Much Energy Does It Take To Fire A Coil?

The condition of a spark plug can tell you a lot. This video is sponsored by Standard Motor Products.

CC: When analyzing the performance of an ignition coil, some technicians will use a scope to analyze the firing event.  A secondary ignition waveform is not just about the coil, it is also about the resistance of the air and fuel mixture inside the combustion chamber, as well as the cylinder pressure.

The firing line is the amount of voltage required to ionize the plug gap. Lean mixtures and higher cylinder pressures will increase the required voltage

Once the gap is ionized, the burn line is where spark is occurring across the plug.

It is important to look closely at the burn line. The “hashy” look is the changing resistance across the plug gap as the spark moves through the layers of fuel and air.

Now, imagine the air and fuel inside the combustion chamber as ohm resistors between the spark plug electrodes. If you increase the distance between the electrodes, you are increasing the amount of air between the electrodes and the value of the resistor between them. As cylinder pressure increases and fuel mixture changes, the amount of energy required to fire the plugs also increases. The resistance also changes because the amount of fuel changes the resistance.

Less fuel means higher resistance between the two electrodes of the spark plug. In the waveform, you can see this as the spikes change in height. Also, the burn line might be higher and shorter. But the sign that there is a lean cylinder is the spike on the end of the burn line. In some cases where the fuel injector is making the cylinder run lean, the two peaks might be the same height when the throttle is snapped or the engine is put under load. This is the leftover energy in the coil because the resistance in the cylinder was too great for the coil to fully fire.

The shape of the waveform will not only be influenced by the air fuel mixture, it will also be influenced by the condition of the spark plugs. This is why it is critical to look at the condition of the spark plugs as part of any coil diagnostic procedure.  It is also possible on many COP systems to analyze the secondary ignition waveform on all cylinders so the technician can compare the pattern on various cylinders and hopefully pick the faulty one out of the good ones. 

To summarize:  You can have a strong ignition coil such as this one from Blue Streak Import Ignition Coils, but still have a weak looking pattern depending on the air/fuel mixture and in-cylinder pressures.  It is important to understand how all these things come together to produce a strong combustion event.

This video is sponsored by Standard Motor Products

You May Also Like

Rick Schwartz: M&A Trends Affecting the Aftermarket

Schwartz Advisors’ Rick Schwartz delves into his career history and the breadth and depth of the firm’s expertise.

The Schwartz name is synonymous with the automotive aftermarket. It started with Mort Schwartz, an engineer by training who served as chairman and CEO of four different automotive aftermarket companies from the 60s to the 90s. Mort's service to the aftermarket, including as a member and chair of various aftermarket committees, spans more than 40 years, and now his son, Rick, is following in his footsteps to make the Schwartz name a leader in M&A advising and business growth strategies in the industry.Rick received his MBA from USC's Marshall School of Business, and while his father grew and ran companies in the aftermarket, Rick's career spans multiple industries working in management positions for the likes of Macy's, Nestle and The Upper Deck Company early in his career. He gained C-suite level experience as the COO of a health and fitness company before joining forces with his dad to create Schwartz Advisors, an M&A and growth consultant for companies in the automotive aftermarket.In some ways, we sat around the dinner table one day and my dad said, I've got an idea. What do you think about this?" Rick explains. "One of [his goals was] to start a company that would be an advisor to the industry. That's a company that didn't exist when [he] owned his WDs. At the time I was running a company in San Diego1, and he knew that I wanted to do something more entrepreneurial and something that touched on the private equity world. He wanted to see something that could really provide value to the industry."In 2006, Schwartz Advisors was born, and since then, the firm has added 12 industry experts from different segments to consult on various deals and strategies.In this episode of AMN Drivetime, sponsored by AISIN, Rick delves into:The reasons why he initially studied international relations (1:00)Lessons he learned from working at large companies in different industries early in his career (1:44)How Schwartz Advisors was born (2:54)The breadth and depth of Schwartz Advisors' expertise (4:02)Trends in M&A in the macroeconomy and the automotive aftermarket (8:02)The types of business that are a good fit for the "buy-side" and "sell-side" of acquisitions (10:22)Lessons Rick learned from his father, Mort (12:42)Rapid Fire questions (14:18) AMN Drivetime is sponsored by AISIN. Find more episodes here.

Road to AAPEX Season 2 Ep. 2

Episode 2 of Season 2 of The Road To AAPEX explains the birth, decline and revitalization of America’s original highway.

Road to AAPEX Season Two: The Lincoln Highway

This year, the spotlight shines on a 2002 Lincoln Blackwood as it travels on a historic journey along the Lincoln Highway.

The 4 P’s of GSP’s Growth with Michael Ceritano

Ceritano describes the ways GSP North America has grown and what he feels has been integral to its success.

Autologue’s Jim Franco: Opportunities in Today’s Market

Find out why Jim Franco is as energized as ever about the business opportunities he sees in the market today.

Other Posts

Oil Coolers and Lines

Damaged, clogged, or corroded fluid coolers shorten the life of any vehicle. Sponsored by The Group Training Academy.

Flexible Fuel Lines

The chances the fuel lines will spring a leak are increasing. Sponsored by The Group Training Academy.

Climate Control Modules

HVAC control modules may fail when the contacts and switches become inoperable. Sponsored by The Group Training Academy.

Preparing for Hybrids and EVs

By preparing now, you can reassure your customers that your skills are up to the challenge.