[COLOR=red]WARNING![/COLOR] Beware Bosch platinums!

[asemstr]

Don't get me wrong! Bosch platinums, +2s, and +4s are great sparkplugs, but like fire they have to be used under the correct circumstanses to prevent complications! As a automotive tech I've come across a large number of driveability cases that stemmed from the use of these plugs in vehicles with ignition systems that were incompatible with them so I'de like to ask your pardon for a moment while I dust off the soapbox and bore you with some of my observations on this issue. First I'de like to mention the ignition systems that perform well with these plugs... COP (Coil On Plug), and HEI distributer type systems in which each plug has it own independent secondary ckt can benefit from these plugs, but you do need to consider they're higher temp rateing. Now the problem. Alot of late model vehicles use a loop style ignition system in which one coil fires 2 plugs with each secondary discharge event. One plug fires dureing the exhaust stroke (waste spark), while the other initiates combustion dureing the power stroke. This results in a pattern like this... Induced power leaves the coil through tower A, Jumps gap in plug A (center-side electrode),passes through the engine block, Jumps gap in plug B (side-center electrode), any remaining power returns to coil tower B. This is where the issue comes up, the Bosch platinum's center electrode design produces a bias or bottle-neck that conflicts with the flow of power through the gap in plug B like a diode plug blocking reversed polarity. In exsteme cases the result is misfire, weak, or dead cylinders. In others they cause a lack of power, hiccups, poor mileage, rough idle, hesitation on takeoff, and mild miss under load because of the weakened spark in the "B" plugs! These headaches can be avoided if you know what systems use this design! Systems with coil packs that pair cylinders, coils with 2 secondary output terminals, and Hybrid COP will not benifit from the installation of these plugs! So if you come across these systems, or you aren't sure about the system in the vehicle in question its best to use a good quality standard double platinum style or OEM reccommended spark plug versus a Bosch platinum series plug. Thanks for your patiece. Hope this thread will be useful (falls off soapbox)

[curtis73]

Thanks for the heads up. I've also seen issues stemming from these multiple electrode plugs, but never heard it explained quite this well.

Stepping up on the soap box beside asemstr, In my little opinion, nothing beats a repeatably consistent single spark kernel, which is why all of my cars have a single-electrode traditional spark plug chosen based on each application.

['97ventureowner]

Years ago, I worked for awhile selling auto parts. I can't tell you how many people came into the store with driveability problems after they installed aftermarket spark plugs. A common brand that caused a lot of the problems was Bosch. I reccomended the owners stick with the reccomended plug from the manufacturer, as they pour millions of dollars into research to find the best parts for their vehicles.With OEM plugs you generally get a plug that is matched not only in heat range, but size of electrode, and length. Most of the time the customer went back to the reccomended plug for their vehicle, their problems "mysteriously" disappeared. Sure OEM plugs may cost a little more than other aftermarket brands, but you have to realize that it gives you peace of mind, and you don't have to spend extra time and money (whether you're a DIYer or not) to pull the bad ones back out and reinstall some good ones. I've also noticed lately in auto parts stores that the counter personell are sometimes too quick to reccomend another brand of plug to their customers. It may be related to lack of training or education of the salesperson, or they are too quick to try to make the sale by offering plugs that are cheaper, and many customer don't know that much about their vehicles to know the difference.

[CBFryman]

i wonder howsome vehicles dont use multiple spark plugs for piston engines...
just a thought (wankles use 3-4 in most cases)

[2.2 Straight six]

i think some race cars use twin or multiple plugs, but remember, road cars dont need it, the single OEM plugs are more than sufficient. think like honda type-r plug, people are told not to replace them withing light stages of tuning or some forced induction, because the OEM plugs honda uses are upto the job.

[Black Lotus]

Originally Posted by asemstr

the Bosch platinum's center electrode design produces a bias or bottle-neck that conflicts with the flow of power through the gap in plug B like a diode plug blocking reversed polarity. :

What is the specific difference in the Bosch plug compared to another brand of plug in the center electrode area?

[asemstr]

Originally Posted by Black Lotus

What is the specific difference in the Bosch plug compared to another brand of plug in the center electrode area?

In the Bosch platinum series plugs the center electrode is shrouded by the porcelin plug insulater leaveing only a pinpoint size tip flush with the surface thats understandably difficult to hit! (Exit only! ) (Is there any way I could get this thread fixxed to the top of the board so it will be easy to find Curtis? )

[curtis73]

I put it in the sticky at the top with links to important threads.

[asemstr]

Thank You!