In 1999, Robert Bosch Corporation introduced a new breed of premium spark plug called the "Platinum +4." The long life plugs, which retail for around $6 each, have a unique four pole electrode design that eliminates wear, resists fouling and improves ignition performance over a wide range of operating conditions.
Surrounding the center electrode, which contains 75% more platinum than previous Bosch platinum plugs, are four "surface air gap" ground electrodes made of a special wear-resistant nickel yttrium alloy. The angle and position of the four electrodes creates multiple spark paths that cause the spark to jump sideways. This has a self-cleaning effect on the center electrode and results in a longer, more powerful spark that reduces misfires for improved engine performance, better fuel economy, lower emissions and faster acceleration.
When these spark plugs fire, the spark jumps randomly to any one of the four ground electrodes. It does not jump to all four electrodes at the same time. This spreads the wear across four electrode surfaces instead of one as is the case with a standard single ground electrode spark plug.
Bosch says their tests have shown the new Platinum +4 plugs can improve fuel economy up to 4.8% over other competitive spark plugs. Fouling resistance is also said to be 33% better.
Though Bosch makes no specific mileage claims for their Platinum +4 spark plugs, they do say the plugs meet or exceed OEM requirements for 100,000 mile replacement intervals. Bosch says the plugs show almost no increase in firing voltage requirements after 100,000 miles of operation. Bosch has also run tests where the plugs have gone over 150,000 miles with no appreciable wear, so these would seem to be lifetime plugs for many vehicle applications (unless, of course, the engine is burning oil, in which case fouling might occur).
Another unique feature of the Platinum +4 is that the surface air gap between the center and four ground electrodes is factory present to 1.6 mm and is nonadjustable. No attempt should be made to adjust or change the air gap when the plugs are installed, even if the air gap specification is different from that specified for a standard spark plug. The wider gap of the Platinum +4 is necessary to achieve the advantages above.
Not For All Engines?
Bosch spark plugs are original equipment on most European makes, as well as some General Motors and Ford engines. Platinum +4 spark plugs are available for a wide range of applications, but may not be available for all engines. The best advice is to follow the application listings from Bosch for choosing the correct replacement spark plug. If a Platinum +4 plug is not listed for your engine, it means Bosch has not done the verification testing to make sure a Platinum +4 will have the correct heat range and performance for your engine.
When Bosch lists a spark plug for a particular engine application, the spark plug must first pass a full battery of OEM verification tests similar to those required for original equipment spark plug applications. So if a Platinum +4 is not listed for your engine, it only means Bosch has not done the verification testing for your engine application. Bosch might have a Platinum +4 that would work in your engine, but until they have fully tested the application, they won't list it.
This has led to some misconceptions about the suitability of Platinum +4 plugs in certain kinds of engine applications, such as turbocharged and supercharged engines. The reason Bosch does not list Platinum +4 plugs for many of these applications goes back to the validation testing requirements. It's an expensive and time-consuming process to do the validation testing, so for limited volume applications it has not been a priority for Bosch. Their focus has been on the broader high volume applications.
Bosch has indicated that in the future, they may offer Platinum +4 as well as other plug designs for some of the newer European and domestic turbocharged engine applications.
We have also seen comments on various blogs and automotive forums by people who say they have experienced fouling and misfiring problems when they replaced their original equipment brand spark plugs with Bosch Platinum +4 spark plugs. We suspect that in most of these cases, any misfires that occurred were likely lean misfires, not ignition misfires, due to intake manifold vacuum leaks or dirty mass airflow sensors. If a Bosch spark plug is listed for your engine, it should perform the same or better than the OEM spark plug.
People can get into trouble trying to match a replacement spark with an OEM spark plug if the visually compare the plug diameter, thread pitch and seat. Two plugs may appear to be similar, but have quite different heat ranges. If they install the wrong plug, it may run too cold, foul and misfire. If the plug runs too hot, it can cause detonation/preignition. This can happen with ANY brand of replacement spark plug. That's why you should always follow the spark plug manufacturers application listings or their cross-index guide.
Bosch does test and compare the heat range of their spark plugs against the OEM spark plugs on engines where other brands of plugs are used. If Bosch has a spark plug that matches the heat range of the OEM plug, they will list their replacement plug for that application. If they do not have a spark plug that closely matches the OEM plug, they won't list it as an application.Voltage Demands
Some people have questioned whether or not Bosch Platinum +4 spark plugs are okay to use with waste spark DIS ignition systems. On these applications, two spark plugs that are opposite each other in the firing order share an ignition coil. When one spark plug fires on its compression stroke, the other fires on the exhaust stroke, but with reverse polarity. This can cause metal to transfer from the side ground electrodes to the center platinum electrode, creating conditions that may lead to misfires with ordinary spark plugs. So double platinum spark plugs or plugs with multiple wear-resistant side electrodes such as the Platinum +4 or +2 are usually recommended for waste spark ignition systems.
The wider 1.6 mm air gap on the Platinum +4 and +2 plugs has a spark path that is about 45% longer than a conventional J-gap spark plug. However, because of the way in which the plug fires, the voltage demand is actually lower than a standard J-gap plug says Bosch.
More Bosch Spark Plugs
Since the introduction of the Platinum +4 spark plus, Bosch has also come out with slightly less expensive (around $4 to $5) Platinum +2 spark plugs which have two side electrodes instead of four. The performance advantages are similar, though the theoretically lifespan may be slightly less because the plug has two ground electrodes instead of four.
Their latest plug is the Bosch iR Fusion spark plug that feature an iridium/platinum center electrode with four yttrium side ground electrodes. This plug sells fro around $8 to $9 each. Like the Platinum +4, these plugs have a preset surface air gap of 1.6 mm. Bosch says the iR Fusion plugs can be used to replace OEM iridium spark plugs in many engines.
When choosing replacement spark plugs, follow the application listings in the catalog. If Bosch does not list one of their plugs for a specific engine application, there is probably a reason why (wrong heat range or incompatible with the type of ignition system or operating conditions). Use the type of plug Bosch recommends for your engine application (ir Fusion, Platinum +4, Platinum +2, Platinum Plus or Super Plus), or if there is no listing replace your old spark plugs with the same OEM brand.
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Bosch has introduced a new Original Equipment design fine wire Double Platinum spark plug to complement its OE fine wire Iridium plug launched in 2011 and the OE fine wire Platinum plug launched in March, 2012. As with Bosch's other OE fine wire plugs, the Bosch Double Platinum plug line is based on the latest original equipment materials and manufacturing technology, and delivers extended performance life and durability.
Bosch says their new OE Fine Wire Double Platinum plug delivers improved ignitability, power, acceleration and throttle response by employing fine wire laser welded center electrode technology, and is designed to last three times longer than a standard copper core plug. The spark plugs are made using a 360-degree continuous laser welding process to fuse the platinum tip on the center electrode. This promotes durability and long life, giving the plugs improved resistance to cracking that can be caused by thermal shock and increased combustion chamber pressures. The fine wire electrode design makes cold starts easier and improves throttle response. The nickel-plated shell with rolled threads provides anti-seize and corrosion protection for the life of the plug.
Bosch says their new OE fine wire Platinum plugs are compatible with the latest Gasoline Direct Injection (GDI) and turbocharged engines. Such applications require locating the spark gap in a precise location within the combustion chamber for proper ignition performance.
The complete line of New Bosch OE fine wire Double Platinum plugs offers 25 SKUs covering over 70 percent of the North American vehicles in operation, including over 86 percent that were originally equipped with double platinum plugs. Plugs are pre-gapped for most common applications.
All Bosch OE Fine Wire plugs are backed by both a customer satisfaction guarantee as well as the industry's only Professional Technician Warranty, which covers labor/repair costs for a period of one (1) year from the date of installation when installed by a certified repair shop.