When did Ford stop using two-piece spark plugs?
Ford largely phased out two-piece spark plugs in favor of one-piece designs during the late 1980s to early 1990s, with the transition largely complete for mainstream models by the mid-1990s.
Understanding this change requires looking at how Ford’s engines evolved and how spark plug construction affected maintenance and replacement. Two-piece spark plugs, which separate the center electrode from the shell during manufacture, were gradually replaced by one-piece construction that is easier to mass-produce and more robust against electrode wear. The shift varied by model year and engine family, and there were a few older or less common engines that retained two-piece designs longer than typical passenger cars or light trucks.
Timeline of the transition
Below is an overview of the general timeline across Ford's mainstream lineup, noting that there were exceptions depending on model and market.
- Early 1980s: One-piece and two-piece designs coexisted as Ford’s suppliers experimented with manufacturing improvements.
- Mid to late 1980s: Ford moved toward standardizing on one-piece spark plugs for most engines, reducing the use of two-piece designs.
- Early 1990s onward: The vast majority of Ford engines used one-piece spark plugs; two-piece designs became rare in new production.
In practice, the changeover was largely complete by the early 1990s, with two-piece plugs remaining only in older or specialty engines and in certain markets where retrofits were slower to adopt.
Engine families and notes
Passenger cars and light trucks
Most Ford passenger cars and light trucks from the early 1990s onward used one-piece spark plugs. Replacements for these engines should match the one-piece specification in the owner's manual or parts catalog.
Older or specialty engines
Some classic or early-generation engines may have arrived with two-piece plugs and could retain them into late 1980s or early 1990s in limited supply or in specific markets. If you own or service a vintage Ford, verify the exact plug design from the service literature for that model year.
What this means for owners
If you are maintaining a Ford from the 1980s or earlier, you may encounter two-piece spark plugs, but for most late-1990s and newer models, one-piece plugs are standard. When replacing plugs, always consult the vehicle’s service manual or OEM parts catalog to confirm the right type and gap specification for your engine.
Summary
Ford largely phased out two-piece spark plugs in favor of one-piece designs during the late 1980s to early 1990s, with the transition largely complete for mainstream models by the mid-1990s. Always verify the exact plug type for your specific engine and model year to ensure proper replacement.
What year did Fords have the bad spark plugs?
In earlier models (think 1997 to 2003), the cylinder heads had too few threads to hold the plugs properly. That means over time, they could literally blow out while you're driving. Scary, right? Then, from 2004 to 2008, Ford made changes.
Why does the Ford 6.2 have two spark plugs?
Using...... 2015 Ford F-350 with 6.2L engine shows...... F-350 SD would probably be different. Ford's 6.2-liter engine uses 16 spark plugs, two per cylinder. This is to better control the spark and ignition, as well as better fuel economy, performance, and emissions.
What year of F-150 to stay away from?
You should stay away from Ford F-150 model years 2004–2008, which are known for severe engine and transmission issues, and model years 2011–2017, which have issues with early EcoBoost engines, transmission problems, and other defects. Specific years to avoid include the 2004, due to a widespread and expensive 5.4L Triton V8 engine, and the 2015-2017 models, which had issues with their aluminum bodies, EcoBoost engines, and transmissions.
Years to avoid
- 2004–2008: These years are notorious for problems with the 5.4L Triton V8 engine, including spark plug breakage, cam phaser failures, and timing chain issues. Transmission problems and electrical system failures were also common.
- 2011–2013: These models had significant issues with the 6-speed automatic transmission, including hard shifting and slipping.
- 2011–2014: Early EcoBoost engines in this range had problems with intercooler condensation, carbon build-up, and spark plug/ignition coil failures.
- 2015–2017: The introduction of the aluminum body brought new reliability concerns. These years are known for problems with EcoBoost engines (particularly the 2.7L), the 6-speed automatic transmission, and some door and brake issues. The 2015 model is also cited for turbocharger and timing chain problems.
How to choose the right year
- To find a reliable F-150, consider model years after 2017, such as 2018–2020, which had significantly fewer reported problems.
- Avoid the problematic years listed above, especially if you are looking for a used truck.
- The 2004-2008 models should be avoided, as they are known for the expensive 5.4L Triton V8 engine, and the 2015-2017 models had numerous problems with their new aluminum body and EcoBoost engines.
What is the difference between old and new spark plugs?
Old spark plugs can waste fuel by failing to ignite the air-fuel mixture effectively, leading to poor combustion. This reduces your engine's power output and increases fuel consumption. New spark plugs ensure more efficient fuel burning, helping you get the most out of every tank.
