spark plugs

[kubota99]

Originally Posted by jack black

Hi everyone.

I was changing oil today and decided to check sparkplugs to see how they are wearing at 70,000 miles. The plugs came too easy for so many miles. It turned out the dimwit previous owner replaced 120,000 mile OEM iridium with some aftermarket junk. Bosch Platinum +4. What is this junk?



The plugs looked just like these:

Funny you call these junk! They're the top of the line platinums.

As for the pictures you just posted, my NGK's I had in 3 weeks ago did the same thing than those Bosch plugs.

[jack black]

Originally Posted by kubota99

Funny you call these junk! They're the top of the line platinums.

As for the pictures you just posted, my NGK's I had in 3 weeks ago did the same thing than those Bosch plugs.

Well, I called them junk, because I was pretty sure they were not as good as the OEM NGK long life 0.7mm Iridium center/platinum puck ground strap plugs. I'm familiar with that OEM plug as I had the same thing in my RIP corolla with 1ZZ-FE engine.

I knew about frequent problems with defective Bosch plugs, but, not being familiar with this weird 4-ground electrode, I looked it up. Apparently they are notorious for misfires and poor engine performance.

Part of the problem is explained in this study: http://wenku.baidu.com/view/d5c9374c...fa1c7cde7.html

+4 were the worst plug in that study (table 9) due to the massive +4 ground electrode quenching the flame kernel. Notice that the +2 did actually well. More is not better.

Another problem is the cheap tiny 0.4 mm pure platinum electrode. Long life plugs require either 0.7 mm iridium or 1.1 mm platinum electrode (and platinum on ground electrode). 0.4 mm pure platinum has very short life, no more than 20,000-30,000 miles.

Clueless +4 buyers (like the previous owner of my car) are sucked into buying this overpriced, low performance, and low life plug, keep it forever (platinum, baby) and have nothing but problems. I'm swapping them for denso platinum TT plugs this weekend.