Hello all.

I have an 08 Ranger 2.3. (145 K miles) Vehicle purchased in January after my 20 year old (98) Ranger 2.5 ( 201 K miles) died due to my negligence; Failed to Change Timing Belt. I will be undertaking a number of maintenance projects that will consist primarily of changing all of the fluids and ignition parts ( plugs - wires - coil pack if nec. ) Enough !!! get to it !!

My owner's manual prescribes that the spark plug gap should be .049 to .053; My Haynes manual is the same. The Ford dealer - parts guy indicated that the correct Motocraft plug is SP439A and are selling for $19.95 each. I asked what was the gap specs. The guy said he wasn't a mechanic and he didn't know. This is a ridiculous price and the service guy ( on phone) wasn't interested in helping. As a result, I researched substitution charts and decided on the NGK G-Power Platnium TR5GP. Accoring to it's specs they are the gap is ,044 for my vehicle. I'm no expert, but the range between .044 and .053 is far too big.

Q: what should I gap the spark plugs? ( Canadian winters -22º to 86º+ F.)

 

Welcome to the forum

Wider gap is better for cold starts and low end power
Narrower gap is better for higher RPM use

Wider gap is a stronger spark but there is less recovery time for the coil, so engine can misfire at higher RPMs if it is too wide

Narrower gap is a weaker spark but coil has more recovery time so good for running higher RPMs for longer periods.

Car makers spec average gap for average use, you can set gap .005 in either direction without issue but with better performance that that direction provides.

BUT.........................things change over time, SP-439 comes pre-gapped at .044 and that is now the recommended gap for the Mazda L 23NS(2.3l duratec) engines

At .044 you would get longer life as the plug gap widens with wear.
If you had a problem with cold starts then you might want a bit wider, but I suspect the .049-.053 was an engineers spec without benefit of hindsight over years of use.
Mazda L 2.3l was first made in 2001 so spark plug gap was set that year by the engineer, there are now 17 years of use to have that fine tuned to "best gap" to start off with, .044

The 2.3l Duratec also runs at least 9.6:1 compression ratio so spark doesn't need to be all the strong even cold, at that ratio its hard to STOP self-ignition for 87 octane fuel, lol.

 

I'm not up on all the science and tech but I just did my 09 2.3's plugs. I used autulite iridiums and gapped at .051. My engine starts and runs beautiful at this spec.

 

Many thanks for your valued response. I'm glad to hear the compression ratio is such that it is forgiving / versatile.

You referenced Mazda 2.3 Duratec engine. Is that the 2.3 engine in my 2008 ?

 

Thanks for the input. I will remember that gap.

 

Yes, Ford renamed the 23 Mazda L engine 2.3l Duratec, so that was in all Rangers from 2001.5 and up, to 2012, end of our Rangers

You can read about it here: https://en.wikipedia.org/wiki/Mazda_L_engine

 

Many thanks for that info.

The Wiki was very interesting.