Bosch Platinum II - JUNK

[phils97bonn]

I've had some engine roughness with an occasional misfire on this beast so I checked the wires - sure enough, fried. Open
resistance (infinite ohms) on 3 or 4 of the 6 plug wires. Ya, I had way too many miles on 'em. Anyway, I replaced the
spark plug wires with a Delco set and it did run some better, only a slight bit of roughness at idle. Well, I "knew" it couldn't
be the plugs 'cuz I just put some Bosch Platinum II (these have a tiny needle-like center electrode and 2 ground
electrodes) plugs in just 28,000 miles ago! I figured these otta be good for around 60K miles or so. WRONG! I pulled 'em out
today and 3 of the 6 had no center electrode coming out of the center insulator - Gone!

I've seen several negative comments on this board and others about Bosch and how you should avoid them. I figured it was a little
over-emphasized as to their low quality. Well, I'm a believer now. I will join the club and say Bosch plugs (at least these Platinum IIs)
are JUNK! (well OK, maybe not junk in all cars).

I took the advice of some folks here and put in NGK TR55IX (Iridium IX) plugs today and the idle is smooth as glass.

Just wanted to share this info.

[95naSTA]

Yep, Waste spark and platinum plugs are a no go.

More info here: http://buickforums.com/forums/showthread.php?t=6622

[phils97bonn]

Yep, Waste spark and platinum plugs are a no go.

More info here: http://buickforums.com/forums/showthread.php?t=6622

Thanks for the link nasta. Ya, I didn't know about the reverse polarity issue on these ignition
systems. I just figured they fired twice as often - not quite that simple. But still, It makes me
wonder about the overall durability of the Bosch plugs - even in the "right applications".

[1oldman]

my personal experience has been that Bosch anything on these cars is junk. Bosch works fine on other cars (I don't know which ones), but not these. - BC

[SSEiMan01]

Bosch is OK on some European cars. My Mercs had a lot of Bosch parts stock.

The main problem was the platinum plugs in this case, not necessarily the brand of them.

[1oldman]

Bosch is OK on some European cars. My Mercs had a lot of Bosch parts stock.

The main problem was the platinum plugs in this case, not necessarily the brand of them.

Bosch O2 sensor made the fuel mileage worse. I changed to ACDelco or Denso and picked up about 2mpg - BC

[Jrs3800]

Just to note I saw a lot of issues in the GM HEI systems with Bosh Plats as well.. They can say whatever they want but even the HEI was doing the same thing with the Bosch Plats....

Years ago I quit running Bosch O2's and Plugs due to the problems that kept coming up with them..

[Wes]

Is it really a problem with all platinums, or just Bosch? The stock 41-940s are platinum and last a long time.

[Jrs3800]

The Bosch are the ones having the issues...

[Wes]

The Bosch are the ones having the issues...

That's what I thought, but I see all platinum thrown in the same category falsely sometimes. For NA I am unaware of any issues of a plug based on it being platinum alone. For a SC engine, I know it is not recommended. Probably why the delcos call for the 41-101 for the oe plugs, as those are iridium, and not platinum. I have been running the NGK $2 resistor plugs in mine with great results.

FWIW, I have heard some anecdotal evidence, on a number of occasions that the Bosch +4s work well in Harleys, and also in the ranger 4 cylinders that use 8 plugs.

[Jrs3800]

This is what I always say...

Either Copper or Iridium for SC

Copper, Platinum or Iridium for NA

Bosch Plats work ok in some and horrible in others like our GM DIS.. when I tuned up my 03 I used the OE AC Delco plug.. No reason for me to use anything else...

My 95 Bonneville has had the same TR55's for the last handful of years... I am sure its way past due for a change... But I have had no issues...lol

[rustyroger]

The shop I worked at fitted Bosch platinum plugs to several customers cars back in the '80s, EVERY SINGLE ONE came back to us because they wouldn't start in the mornings. We replaced with NGK or Champion items and they were fine after that.
But even so we lost a couple of customers because of it, I won't use anything Bosch anymore if I can help it.

Roger.

[nickdalzell1]

Bosch Platinums and Quad-fires were bad for Mopars too. i remember my Fifth Avenue running perfectly fine when i pulled in one night to clean dad's office (it was one of my early jobs) but soon as i tried to leave nothing. the problem? all eight Platinum Quad-fires. ever since i replaced them in that car with Autolites, i have since used Autolites in all my cars since.

[Jrs3800]

Autolite is a pretty good plug..

[SSEBonne4evr]

Good old Champion coppers in my 96 SE for 4 yrs now.
Excellent performance.
AC Delco's would not hold the gap for some reason.
Kept opening up.

[Wes]

Good old Champion coppers in my 96 SE for 4 yrs now.
Excellent performance.
AC Delco's would not hold the gap for some reason.
Kept opening up.

Ewww, I don't like putting champs in my lawnmower. lol, j/k man. But seriously though, NGK equivalent of Champions are superior for usually the same price. Just my 2 pennies though.