My '98 developed a miss at 35k miles. I took it to the dealer and they replaced a coil pack under warranty but said plugs and wires needed changed and were not covered. So much for 100k tune up interval. I replaced plugs and wires my self. Used Bosch platinum. At 85k the miss came back. Changed another coil, still missing. Changed wire, still missing. Changed plug. Fixed it. The plug had started leaking around the insulator and the metal base, thus causing the miss fire. Now with 99k another plug has failed in the same way. As soon as it warms up I will put the rest of the plugs and wires in. Any other problems with Bosch plugs?

 

My factory platinum plugs were shot at 45k. From what ive been able to find, its not worth the extra expense of the platinums.
With my Expedition racking up 25k miles per year, Ill wear them out quickly.

Tony Warren
Nebraska

 

I had the same problem with Bosch in a Ranger. Installed
Motorcraft double platinums, no more problems!!!! The
Bosch seem to run TOO HOT!!!!

 

What wires are you changing? The coil sits right on top of the plug, thereby eliminating the wires.

 

Not on the 4.6. It has the 2 coil packs(4 cly. each) mounted on the front of the valve cover. I think the 4.6 got the individual coil for each plug in '02. I think.

 

With the spark polarity of Ford's EIDS, just more of a reason to
use Motorcraft double platinum plugs.....

 

I dumped the stock plugs in my wife's 2000 Expedition about a month after we bought it.

I use Bosch +4's in *all* my vehicles that they are made for, and I have *never* had a problem.

I do not use any other Bosch plug so I can't comment on it, but my bike did come stock with dual electrode Bosch FR6DDCs. They oil fouled fast. The +4s took care of that pronto.

The only thing I know about the +4s for sure is that each vehicle's coil, individual or multi, has a slightly different operating voltage. Each engine's variables are just that; variable. Fuel/engine/air temp, true compression ratio, fuel/air density, potential for oil fouling, etc...

The +4 design uses a cone-shaped tapered center platinum electrode within a group of 4 ground electrodes. Depending on the variable conditions in the engine, the plug has a comparatively tremendous amount of surface area upon which the spark can jump the gap. The truly intelligent part is the tapering, and that's what makes these plugs special and different than flat-face marine plugs. The gap is variable (large at the top and small at the bottom), so a strong spark jumps near the top, and a weaker spark jumps near the bottom... but it jumps! I do not know of any other plug that has a variable gap.

Depending on operating conditions, fuel, etc..., the spark location will constantly vary, and I don't think it's normally possible to foul one of these plugs. If a deposit forms in one area, the spark just jumps in another.

So, the point here is that if you're seeing spark jumping before it reaches the plug, and you're losing coils/packs, then there *may* be a problem getting the spark to the right place (a plug ground electrode).

With the obvious usual culprits consisting of bad wires, boots, no dielectric grease, wire routing, etc. aside, then perhaps there is a problem with the plug fouling?

If that's the case, then the discharge from the coil has to go somewhere else each time that it can't jump the gap to ground.

Electricity always takes the path of least resistance, so *any* spark other than on the plug is an indicator that the resistance is higher closer to or at the plug then where it jumped to ground.

My suggestion is to try a set of these. While I never checked the before & after MPG, I expect that they would perform to the manufacturer's best-performance scenario. I *did* notice that engines I used them in idled smoother.

Prices vary, so shop around. I think I've paid around $5 each on average, but these plugs are definitely *not* snake oil.

AJ

 

With the opposite polarities of the EDIS, I DO NOT recommend the
Bosch +4, due to the design of the electrodes (being asymmetrical, just like you described!). If you look at the platinum
"bead" on the Motorcraft double platinums, there is symmetry on
the outer, and center electrodes......

 

I should have ended my post with this:

"Your Mileage May Vary...."

They do work fine for me (about 60k on them now).

 

Don't get me wrong, I believe the best plug depends a lot on the
application. For Ford's ignition system design, I believe the best
plug for it (correct heat range, etc.) is Motorcraft. I will also say
the only plug I run in my gas Mercedes is Bosch, but nothing
except Motorcraft in my Ranger....

 

The gap is variable (large at the top and small at the bottom), so a strong spark jumps near the top, and a weaker spark jumps near the bottom... but it jumps! I do not know of any other plug that has a variable gap.

Electricity always takes the path of least resistance, so *any* spark other than on the plug is an indicator that the resistance is higher closer to or at the plug then where it jumped to ground.

To me these two paragraphs contradict each other. Electricity wont just jump a larger gap because it can. No matter how you entice it.
After the first couple combustion cycles, it will not be equal from one electrode to annother. It will then just fire on the least reisitant electrode until it becomes more resistant than one of the others.
It is not a generator of any kind. V in = V out You will not get any more spark than with a standard platinum plug.
I asked a question like this in a couple forums, not one person could come up with a reason why these pluggs should work better than any other plug. Lots of testimonials but no scientific proof. Testimonials are easy to get, but hard to prove/disprove.
I also never hear of anyone haveing problems with regular plugs fouling, so why spend the cash on pluggs that shouldnt foul?

If it looks like a duck, walks like a duck, quacks like a duck.
ITS A DUCK!

Save your money.

Tony Warren

 

The 2 plugs did not foul. The compression was pushed out between the porcelin and metal part of the plug, causing a misfire code in the computer.

 

Yes Mitch. I read your post. I was replying to the RFC on Bosch plugs and trying to give as complete as possible info.

 

Sorry, i kinda got off track as well. Not a fan of bosch pluggs, too many problems.

Tony Warren
Nebraska

 

So problems like this are not rare with Bosch?