Bosch vs NGK
 

I just experienced a problem with my daughters 99 Protege 1.6 Litre, when using Bosch Platinum plugs. Car developed a misfire on cyl. 2 at times, as confirmed by my OBD2 scanner. I pulled the plug and found carbon tracking that ran down the side of the plug and grounded itself to the valve cover. I installed these plugs 9K ago. I have heard from some people to not use German plugs in Japanese cars. This however was my first bad experience with Bosch plugs. I use Bosch plugs in my wives Infinity J30 for 100K and have never had a problem. Just thought I'd pass on the experience.

I'm new to the club and look forward to sharing ideas & info. with other Mazda owners. Happy Holidays!! Thanks, Danny

I have read about others having problems with Bosch and other non-recommended plugs.
I don't really know that much about them, but a search should come up with some answers.
There has been much written.
Welcome to the club.

Stick with the NGK copper plugs. They're the best for our cars.

I agree, you should stick with the manufacturers plugs, you can never go wrong. stay away from premium plugs unless you have a application for it such as irridium plugs for Nitrious or other demanding motorsporting.

I have a thread on Bosch Uses http://www.protegeclub.com/showthread.php?t=35918 http://www.protegeclub.com/showthread.php?t=36000
it was actually a positive experience.

I can validate the results on a fuel economy aspect, we did see a signifacant increase in fuel econ over the NGK IX plugs. With three 400 km distance test between Toronto and London and with two Identical proteges, and swapping the plugs between cars at the midway points of each test to insure the results would be fair based on cars..... but in terms of power, my results are still up in the air because of problems with fair protocol for Dyno testing. The last results were found to be unfair do to not allowing the car to cool long enough for the next test.

Doing a Back to Back tests. We only had a 30 minute window for the test to get it done for free so we made the best of it.

This test saw the Bosch produce ever so slightly more power then the NGK... I beleive the results to be inacurate as well.

We will find out shortly when we do the next dyno... someday soon....

But if you were interested in upgrading your ride, still with NGK Irridium they handle better under pressure, I can't say the same for bosch.... my recommendation would be to use Bosch for standard normal use.

you will get fuel economy from it... it will be very slight maybe a .1% difference but its there

The NGK plugs are better engineered parts than the Bosch ones, that much is true. But I believe that carbon tracking on the outside of the insulator is more likely the result of oil/dirt debris on the inside of the coil boot or cable boot, and not so much part design (unless your specific Bosch part is one of the ones without corrugations in the insulator). If the rubber of the boot is clean, you should have a nice tight seal and flashover will not occur under normal sparking voltage requirements. Examine the coil/ cable boots for cleanliness. It would suck if you spent good money on top notch iridium plugs, only to have the same thing happen to you.

Juddz, I cleaned all plug boots and install the original type copper NGK's. Tracking was taking place as evident by a trail of arching inside the boot. Probably was just dirty.

Usually once arcing starts, it forms conductive carbon trails (deeper than the surface) that no amount of cleaning will fix. If I had that problem I'd replace the wires.

Agreed.