Better ignition?

[LukeBizzy]

Curious...2008 4.0 FX4/auto/160K miles. Looking to add a better ignition for just a little better gas mileage, any performance boost is a plus but mainly mileage. When I got the truck it had what I think is a Standard Ignition replacement coil on it, I swapped in a Blue Streak coil while doing a tune up.
Current mileage is about a average of 14mpg in 2wd. She's my daily driver, with winter coming up & 4wd fun I'm trying to use what I have

I couldn't find any MSD style "add on ignition box" style that would work. Are there any?
Looking at coils. Kind of like the DUI Davis Ignition Screamin Demon coil. Price is comparable to Motorcraft. Any thoughts? Close to just trying it out.

Thank you!

 

[RonD]

First thing is O2 sensors, 12 years or 100k miles after that MPG starts to go down for a number of years before you will get any codes
O2s are the only sensors that wear out on a time/mile schedule

O2s are also the only sensors computer has to calculate the best, most efficient, MPG

Spark plug gap
Spec is 0.054"
That's for average use
0.057" would be for better cold starts and lower RPM/speed driving, under 55mph
0.051" would be for better higher RPM/speed driving, over 55mph

4.0l SOHC makes best torque at 3,000rpm
So best cruising MPG should be 2,600-2,700rpm
Lower RPMs do not always = better MPG, idle is 0 MPG

You can use a BlueTooth OBD2 reader, like $15 ELM327 and Torque Pro App, $5
And watch Computer's calculated Vacuum level in engine while cruising
The Higher the vacuum the better the MPG as long as you are maintaining the speed
I prefer real vacuum gauge for this but I am older, lol
This will tell you the best engine RPM vs load

Never shift to Neutral in a manual or automatic when coasting downhill when you have fuel injection, or when coasting anywhere
One of the benefits of fuel injection is that the injectors can be shut off when coasting, foot off the gas pedal, and the computer will do just that if engine RPMs are above 1,500 and your foot is off the gas pedal

With a Carb this was a good strategy because carb's used Jets, and fuel was sucked out of the Jets by air flow and engine vacuum, and coasting in gear caused higher engine vacuum which sucked more fuel than needed from the idler Jets

 

[LukeBizzy]

Thanks Ron!
Yes, O2 sensors are on my list also, just a little scared to mess with them since they look almost original. Got my truck at 140K & it had stock plugs in it still (.095" gap!) so not much has been messed with.
I've been using HP Tuners for a while now & played with it on the truck. Managed to get the mileage up from 9-10 when I got it between basic tune up stuff & minor tuning tweaks (mainly tuning for ethanol in fuel & MAF tweaks) but there is more in there. Fuel trims are close now & amazingly the O2's are still somewhat-fast acting, but I know they are old & need replacing. Not the easiest to reach either! I do have the Torque Pro app & its my 2nd favorite next to HP Tuners, fyi.

I'm just thinking the basics like a hotter spark is always good Big tires & brick shaped so I'm not looking for 20mpg but 16ish in 2wd on dry pavement would make me happy.

 

[gaz]

@LukeBizzy ,
MSD does make a compatible system for a DiS ignition, the MSD DiS-4, it can run 4, 6 or 8 cylinders; for a COP set up, it will require dual DiS-4's. Multi-spark output up to 3k RPM.

I feel that the DIU Screamin Demon coil pack is the best hi output option on the market.

I bought into the Blue Streak coil line but NEVER again. They have failed me 2 for 2...never again!!

 

[fastpakr]

You could waste your money on an aftermarket ignition setup, but there's really very little to accomplish there.

 

[sgtsandman]

It sounds like you have a lot of preventative maintenance that the previous owner didn’t do to catch up on before you start throwing upgrades to it.

Assuming you still have the stock tire size, you should be seeing something close to 23 mpg on the highway. Even with my 31” all terrain tires, I’m seeing 19-20 mpg on long highway trips regularly. Sometimes even 21 mpg.

Mixed driving is going to depend on the mix. My daily commute is half in town and half highway and I get somewhere between 17-18 mpg.

The O2 sensors are a good start.

Check your MAF in the intake tube by the air filter. It probably needs cleaned.

Look at you Idle Air Control valve and throttle body. They are probably pretty cruddy.

Run some fuel system cleaner too to clean the injectors. Dump a bottle in when filling your tank and run it dang near empty. If your fuel light still works, drive it until that comes on.

What psi are you running your tires at? What is your driving style? There are a lot of little things that can add up and give you crappy fuel mileage.