20uf capacitor for 12v+ coilpack wiring (4 cyl wasted spark)

[16v dude]

I'm trying to find a 20uf capacitor for my 4 cyl (wasted spark) wiring application like the manual suggests to do. http://www.msextra.com/doc/general/sparkout-v30.html. There is a large variety and price difference of capacitors and i don't want to over spend and buy a capacitor that is way overrated for my application. Does anybody know a good capacitor part# to use? Preferably from digikey.com

Any advice would be awesome. Thank you.

[16v dude]

anybody?

[john.p.clegg]

Get yourself down to the breakers yard,Ford coilpacks have them real close...

John

[DaveEFI]

I'm trying to find a 20uf capacitor for my 4 cyl (wasted spark) wiring application like the manual suggests to do. http://www.msextra.com/doc/general/sparkout-v30.html. There is a large variety and price difference of capacitors and i don't want to over spend and buy a capacitor that is way overrated for my application. Does anybody know a good capacitor part# to use? Preferably from digikey.com

Any advice would be awesome. Thank you.

The snag with using 'ordinary' caps from Digikey etc is they are not designed for car mounting - they are made for soldering to a PCB, etc. The EDIS ones I use have mounting lugs which fit one of the coil bolts and a flexible lead with connector.

[walterclark1]

If you go the generic cap route, rather than one from another auto application, be sure you get one that is spec'd for extended temps such as the Vishay 118 AHT series (select values of this series are carried by both Mouser and Digikey). "Normal" temp spec caps can have their life shortened by as much as half due to underhood temps that can hover around 200F (100C) near/on the engine.

Second piece of advice. Specific capacitance values are not critical. This is a bypass function e.g.: smoothing the voltage at the input to the coil - the result of current transients caused by switching on and off the coils in combination with the series impedance of the power source and wiring. What are important parameters are minimum capacitance and minimum voltage, followed by maximum capacitance. I would not use a cap with less than a 25VDC rated working voltage, and basically I go as large in capacitance as the application permits. I ended up with the 1000uf 25V part# MAL211816102E3. It is true that above some value of capacitance and working voltage, where depends on the specific capacitor design and the circuit, that high frequency performance - due to the caps internal series inductance - becomes large enough that it may be necessary to bypass this large cap with a much smaller one to smooth spikes (or to choose a smaller value for the "large" cap). Based on my experience with the Vishay 118AHT series at 1000uf and 25V I would say anything between around 22uf and 1000uf (at the 25VDC rating) should work by itself in this application.

Third. Insulate the cap and its leads with heatshrink tubing to prevent chafe and shorts, then securely mount the cap using a cable clamp around the cap body and locate it as close to the coil power terminal as possible.

[16v dude]

Great advice and information! Thanks for all the input everywone! I very much appreciate it.

I had the engine running without any cap and everything seemed okay but i just thought it would be good to go with what the manual says.

[16v dude]

Yeah when i have the engine running it cuts out every couple seconds but stays running. I notice that the LEDS on the MS stop blinking when this happens (its really sudden). Im pretty sure that this is happening because of a misfire. So i ordered the MAL211816102E3 Cap. Hopefully this cures my issue. I'll will let you know once i have it installed.

[DaveEFI]

Great advice and information! Thanks for all the input everywone! I very much appreciate it.

I had the engine running without any cap and everything seemed okay but i just thought it would be good to go with what the manual says.

The cap on the coil positive is to help cut down RFI. Perhaps mainly for the car audio system, etc - and to to conform to regs for such things. But it may also prevent such interference having an effect of the actual injection microprocessor. So like many of these things it may not be essential. But no reason not to fit it just in case.

[john.p.clegg]

Just a little extra...

Battery and Coil-operated ignition
With the universal adaptation of electrical starting for automobiles, and the concomitant availability of a large battery to provide a constant source of electricity, magneto systems were abandoned for systems which interrupted current at battery voltage, used an ignition coil (a transformer) to step the voltage up to the needs of the ignition, and a distributor to route the ensuing pulse to the correct spark plug at the correct time.
The first reliable battery operated ignition was developed by the Dayton Engineering Laboratories Co. (Delco) and introduced in the 1910 Cadillac. This ignition was developed by Charles Kettering and was a wonder in its day. It consisted of a single coil, points (the switch), a capacitor and a distributor set up to allocate the spark from the ignition coil timed to the correct cylinder. The coil was basically a transformer set up to step up the low (6 or 12 V) voltage supply to the high ignition voltage required to jump a spark plug gap.
The points allow the coil to charge magnetically and then, when they are opened by a cam arrangement, the magnetic field collapses and a large (20 kV or greater) voltage is produced. The capacitor has two functions: 1) it absorbs the back EMF from the magnetic field in the coil to minimize point contact burning and maximize point life; and 2) it forms a resonant circuit with the primary coil of the ignition coil transferring further energy to the secondary side until the energy is exhausted. The Kettering system became the primary ignition system for many years in the automotive industry due to its lower cost, higher reliability and relative simplicity.

John

[16v dude]

Nice bit of information!

That is interesting. Its amazing how a bunch of different people all around the world have developed and invented the amazing new technology that we are using today. Before Kettering came along there was a Belgian named Jean Joseph tienne Lenoir in 1860 who invented the stationary internal combustion engine. Then there were a couple German inventors who helped develop improvements to the ignition system. Karl Benz was the first to make an automobile, Werner Von Siemens invented the Twin-T magneto, Gottlieb Daimler invented the modern day ceramic spark plug, then Robert Bosch came up with the oscillating low-voltage magneto and then he invented the high-voltage rotary magneto (Bosch was the inventor of the first high output ignition system).

Bosch's invention was the standard until Charles Kettering came along with his more reliable system.

[DaveEFI]

Just a little extra...

Battery and Coil-operated ignition
With the universal adaptation of electrical starting for automobiles, and the concomitant availability of a large battery to provide a constant source of electricity, magneto systems were abandoned for systems which interrupted current at battery voltage, used an ignition coil (a transformer) to step the voltage up to the needs of the ignition, and a distributor to route the ensuing pulse to the correct spark plug at the correct time.
The first reliable battery operated ignition was developed by the Dayton Engineering Laboratories Co. (Delco) and introduced in the 1910 Cadillac. This ignition was developed by Charles Kettering and was a wonder in its day. It consisted of a single coil, points (the switch), a capacitor and a distributor set up to allocate the spark from the ignition coil timed to the correct cylinder. The coil was basically a transformer set up to step up the low (6 or 12 V) voltage supply to the high ignition voltage required to jump a spark plug gap.
The points allow the coil to charge magnetically and then, when they are opened by a cam arrangement, the magnetic field collapses and a large (20 kV or greater) voltage is produced. The capacitor has two functions: 1) it absorbs the back EMF from the magnetic field in the coil to minimize point contact burning and maximize point life; and 2) it forms a resonant circuit with the primary coil of the ignition coil transferring further energy to the secondary side until the energy is exhausted. The Kettering system became the primary ignition system for many years in the automotive industry due to its lower cost, higher reliability and relative simplicity.

John

That is all true where the cap is across the points. But in EDIS, it's across the feed to the coil - not the switched side. On a Kettering system, it was common to add a cap across the feed side for RFI suppression when fitting a radio, if not factory fitted. Also to help stop interference to external (to the car) devices like TVs etc. With more and more electronics being used in a car, this cap may also help reduce RFI problems to those.

[jsdevel]

Yeah when i have the engine running it cuts out every couple seconds but stays running. I notice that the LEDS on the MS stop blinking when this happens (its really sudden). Im pretty sure that this is happening because of a misfire. So i ordered the MAL211816102E3 Cap. Hopefully this cures my issue. I'll will let you know once i have it installed.

Did you ever install it?

Sent from my Nexus 6P using Tapatalk

[rickb794]

This topic is 4 years old and 16v has not logged into the forum since 2015.

The cap does not have to be from a EDIS install, you will find the caps on any of the later Ford distributor coils as well.