Ignition Mods & MPG

[4pointslow]

spark

Very interesting, I will be looking forward to any findings you have on this after you finish the M90 install. Of course I am more concerned with 1/4 mile times and Horsepower/Torque output than fuel mileage.

 

[roboron13]

I purchased a used ignition coil pack and have started thinking about a way to delay the PCM to coil pulses to fire the second coil pack. A variable delay based on engine rpm would be more effective but also more complicated. A fixed delay would be a good evaluation project to determine if there is any potential fuel economy or performance improvement from a second spark. Some members have reported idle stability improvements from ignition upgrades.

Has anyone experienced fuel economy or performance improvements after replacing a functional stock coil with something else?

I have a 00' 5.0l. And man, i put 2 of those accel coil packs on, pushing 42,000k volts and honestly, about the past year, every tank, always same driving, went from 11-12 mpg's to 14-15 mpg's. Honest, and that was about 10 tanks ago. Prbly goin to try extending my spark gap next!!!

 

[Fredness]

Why not a coil on plug system using coils paired on the grounds for triggering?

 

[2000StreetRod]

Why not a coil on plug system using coils paired on the grounds for triggering?

That's a good question! It is my understanding that the voltage output of the stock coilpack is adequate for normal max engine speed (6,500 rpm) and modest boost (8 psi). However, for best fuel economy and best performance (especially at high boost) the spark duration needs to be increased. The high voltage spark is created when the electromagnetic field in the coil secondary winding collapses due to the current in the primary winding being interrupted. The duration of the spark is dependent on the amount of energy stored in the coil secondary which is a function of the amplitude of the current flowing, the time the current is allowed to flow, the number of turns, and the volume and type of the ferromagnetic material. The waste spark system used in my Sport with only three control wires fires any individual spark plug twice as often as necessary (on the compression stroke and the exhaust stroke) reducing the time for a coil to build an electromagnetic field. Using two coils for each cylinder with one coil firing slightly later than the other would extend the effective duration of the spark. Using COPs instead of coilpacks would reduce the amount of high voltage ignition wiring but I don't know if there is room for two COPs per cylinder. It is definitely something to evaluate.

 

[Fredness]

The wife wants here Sport Trac boost-free (for now), so we're concentrating on bottom-end and MPG.

What I have found is that hotter coils and opening the gap are great, but there is an increased maintenance associated with that. We went from 70,000 miles on the Motorcraft Double Platinums with stock coil pack, wires and .054" gap to throwing P0300, P0301 and P0305 at 10,000 miles while running a new set of the Motorcraft's, a Screamin' Demon coil pack, LiveWires and a .065" gap.

Switching to an Accel coil pack and .060" gap greatly increased the bottom-end torque, but I'm sure most of that was due to the failing Screamin' Demon coil pack (16 months old). Plug 1 opened to .080" and plug 5 was over .070" and functioned fine until about 4,500 rpm's before misfiring.

 

[malohnes]

Since this old thread was dug up....

2000Streetrod, did you get anywhere with this mod?

 

[2000StreetRod]

Since this old thread was dug up....

2000Streetrod, did you get anywhere with this mod?

Not yet. I started this thread before I decided to add an M90 supercharger. However, I left room to install a second coilpack above the stock coilpack. One of my work tables is covered with ignition wire sets, coilpacks, an ignition module, an electric motor driven trigger wheel and an oscilloscope waiting for my attention. I may get back to it after I finish building and installing an Aviator 4.6L DOHC V8 in my 2003 Explorer. I'm now 70 years old and am trying to focus on heavy duty projects now and save the light duty projects for when I get old.

 

[malohnes]

I'll PM you with some info I think you'll like and may "spark" new interest.

Your current project sounds sweet!