30k spark plugs, to Bosch ZGR6STE2 (big pic warning)

[Dackelone]

Originally Posted by e34m5

For reasons unknown there seems to be some reason that the BMW labeled plugs, albeit with the exact same Bosch number are not in fact identical.

I used the Bosch version the first replacement and BMW the second time. Can't tell any difference in performance.

Usually the only time you can tell that someone used the Bosch plugs, is because after the installation they have drivability issues that were not there before. Some people had then replaced coil packs and injectors only to find out(later) that is was their aftermarket Bosch spark plugs.


I don't know why that is, but its been reported here(and on the e90post) forum many times. I think I saw someone post a picture of the ceramic insulator(cut in half down the plug) - and the BMW looked different on the inside than the Bosch one.


Dack

[hyphy1]

Originally Posted by Freon

Quick update, my fuel economy has gone up noticeably. I was only getting about 18-18.5 before, and I'm now settling around 19.5-20.0 as reported by the dashboard computer. I have a pretty regular drive to work and back, short city drive. It is anecdotal, but is a trend over a almost two weeks now.

I felt the same way with my highway commutes to work. on freeway, im hitting 30+ while driving quite aggressively. had mine replaced at 45K, btw.

[Freon]

I've learned that in objective fields of study anecdotes (ex. a few people reporting issues with Bosch branded injectors [they are ALL Bosch with the same Bosch SKU]) should be taken with a grain of salt. Anecdotes from laymen do not constitute empiricism, and when it does not make rational sense it may be other factors being missed by non-experts trying to troubleshoot issues. Even so-called "professionals" in the tuning industry, i.e. non-factory trained, non-certified "tuners", often seem to be very bad at drawing conclusions. See the thread recently where a guy's charge pipe was popping off because the clip was put in backwards, then one of the other forum members who works on cars professionally responded with poor information.

It's one thing for a few non-experts, or even professionals (which means little more than they take money to do work and does not speak to expertise) to say they thing "X" is the problem. It's another to do a proper, objective test which would include a reproducible test methodology that allows others to get the same results.

As I even admit, my MPG report is anecdotal and not truly scientific or well-conducted test.