18 votes
Accepted

Why the wasted spark in four-stroke motors?

I'm sorry if this ends up being a lengthy answer. The answer to this question is more historical than anything else but first a little background. In a waste spark system an ignition coil has two ...
  • 15.9k
11 votes

Do primary and secondary coil resistances correspond to number of windings?

Unfortunately no. This is because the primary and secondary windings don't use the same wire. The primary uses a few turns of a thick wire. While the secondary uses many turns of a thinner wire. The ...
  • 15.9k
10 votes

Do I change all four coils when I change one spark plug that is faulty

You shouldn't need to change the spark plug coils unless they are faulty, so the answer to your question is no, you don't need to replace the coils again. There probably wasn't a need to replace all ...
9 votes

Do primary and secondary coil resistances correspond to number of windings?

IMHO the only reliable way of telling the winding relation would be to feed an low voltage alternating current with known amplitude into the primary winding and measure the amplitude of the secondary. ...
  • 7,953
8 votes
Accepted

How Common are Voltage Drop Problems?

Voltage drop problems are very common in multi component, multi interface systems. For instance the starter motor has a cable that runs from the battery to the starter. The cable has ring terminals ...
  • 15.9k
8 votes

What vehicle does this ancient ignition coil fit?

Since you said it has Ford on the case, this would most likely be a coil for a Model T. I don't exactly know how you'd test it, but I found this document from a Model T Ford website. I think it would ...
7 votes
Accepted

Do I Need to Ground the Spark Plug When Testing

Yes you should ground the spark plug. In your case the spark plug was close enough to the block to still jump the gap. If the plug was far enough away from metal nothing would have happened. On a ...
  • 15.9k
7 votes

Spark plug and coil only one is bad for 2012 Honda odyssey

If you find the coil is bad, change just the coil. You can do this without issue. If you find the spark plug is bad, change all of them. When spark plugs start going bad, it is a good bet others will ...
6 votes

How to Test an Ignition Coil with a Multimeter

There are three tests that can be preformed using a multi meter. A DIS type coil that services two cylinders works like a transformer. The primary windings are controller by the ECU. The secondary ...
  • 15.9k
6 votes

Why the wasted spark in four-stroke motors?

Some four-stroke engines did have wasted spark ignition. The basic advantage was not needing a distributor, which was one of the less reliable parts of the ignition system. Wasted spark systems were ...
  • 2,929
6 votes

What vehicle does this ancient ignition coil fit?

Be it known that I, Joseph A. Williams, a citizen of the United States, residing in Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in ...
  • 3,862
6 votes
Accepted

What is a vibrator on a Model T ignition coil for?

AKA Trembler Coil The trembler coil was a device called a Ruhmkorff or induction coil, widely used in the 19th century.[3] It combines two magnetic devices on the same iron-cored solenoid. The first ...
  • 7,960
6 votes
Accepted

Yamaha Seca - Motorcycle Idle problems

More than likely, you have an air leak If you haven't cleaned out and rebuilt a bunch of 4 carburetor banks in your life there is a good chance you have accidentally created an air leak in the system....
  • 32.8k
6 votes

Do primary and secondary coil resistances correspond to number of windings?

You could avoid the shock risk mentioned by @Myself, perhaps at the loss of some precision in the measurement, by applying the known source to the secondary winding. That way you're using the coil as ...
  • 14.3k
5 votes
Accepted

Are There any Benefits to a High Voltage Coil Pack?

Go with the standard replacement (the warranty choice is left up to you). High output coils are used in modified engines that have higher combustion chamber pressures from either higher compression, ...
  • 3,363
5 votes

Honda CB400 Super-Four - Power Issue

Background You have two coils on that motorcycle. One coil is for cylinder 2 and 3 the other is for cylinder 1 and 4. It utilizes what is known as a wasted spark system, the spark is fired off on ...
  • 32.8k
5 votes
Accepted

Engine Turns but won't start

It's me, your future self. So it turns out that you're an idiot and all you had to do was fiddle with the choke. That little lever on the carb? That's the choke. I forget which way is open and ...
  • 213
5 votes
Accepted

How is ignition coil feedback useful?

Pᴀᴜʟsᴛᴇʀ2's answer is pretty much correct, at least for Toyotas (the linked post in the OP was for a Lexus aka Toyota). Here is some extra detail. Also "feedback" is used for different things in ...
  • 4,910
5 votes

Can I replace my ignition coil with a ECU?

There are a number of ways to go solid-state ignition and there are a few open source projects that allow you to build your own ECU and loom and utilize an ignition system from something else. One ...
5 votes
Accepted

What are the benefits of direct ignition (coil on plug) system?

Coil on plug has several advantages over conventional distributor type systems: 1) Less voltage loss from the coil to the plug. With fewer connections and the elimination of the distributor rotor to ...
  • 11.5k
5 votes
Accepted

Engine not starting after melted Ignition Coil

This issue is, you have serious cylinder pressure (or should I say, non-pressure) issues. The pressure test results you give (as long as the test was done correctly), shows a massive drop in cylinder ...
5 votes

How does this ignition coil work? Why are there two wires, and where should they be connected?

The usual idea is that with 2 wires; one is ignition controlled 12v and goes to the resistor (block on the side with two terminals) so that the coil receives about 9v during normal running. The other ...
  • 34.4k
4 votes
Accepted

Cooling the ignition coil

Like @ Paulster2 I have never heard of this. I suppose it is possible if you had a coil on the edge of failure that it might fail while overheated. Resistance is a function of temperature. The more ...
  • 19.8k
4 votes
Accepted

How to Test an Ignition Coil with a Multimeter

To be honest you won't get far with a DVOM. While vini_i's answer is correct you can't do this while the car is running. You should be looking into buying a digital storage oscilloscope if you want ...
  • 10.7k
4 votes

Coil On Plug, Testing The Primary Coil

Check out the General Technologies TA500. This tool is quite inexpensive (for its incredible capabilities) and very flexible. Perhaps not for the DIY set, but there's no probing involved and it ...
  • 12.3k
4 votes

How is ignition coil feedback useful?

The ignition confirmation signal is a comeback signal to the ECM. This tells the computer a successful spark has occurred: the coil has launched it's goods. When the signal fails, the computer knows ...
4 votes

Do primary and secondary coil resistances correspond to number of windings?

There were already good answers, I'd like to add some points and also write something about the inductance. Here is a sketch of a typical coil: (Source) Resistance There are in principle two ...
  • 7,017
4 votes
Accepted

Accessing the 1st and 2nd cylinder ignition coils in VW Golf MK5 (55 kw)

Take the white piece out by gently wiggling it. Should come out fairly easily (with some resistance). Then, grab the entire filler assembly and turn it counterclockwise. It has two tabs on it which ...
4 votes
Accepted

Can swapping ignition coils fix a cylinder four misfire?

It normally wouldn't, however, I'm thinking the problem might have been the wiring connector to the coil wasn't making a good connection (or possibly causing an intermittent connection), which was ...
3 votes

How to know if the spark plug or the ignition coil needs to be replaced

To test the coil, as you said there's only one cylinder that isn't working, just switch the coils of two cylinders. For the spark plugs, again you'll just switch two if you want to test one against ...
  • 1,364

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