What's wrong with Bosch +4 Platinum plugs?

[dnguyen1963]

I have read many posts about not using the Bosch +4 platinum plug in a M20 engine. However, there are many drivers out there with these plugs in their engine including me. Personally, I have not experienced any negative effect from using these plugs, but I am not a professional mechanic. What should I be looking for? What are the bad symptoms?

[priapism]

In for responses. Found that my race car had these things in there as well.

Thing is, the regular plugs I bought (Champion 9804 iridium) have a different tip and won't fit the wires I have. I'm confused as to what I can put in there.

[dnguyen1963]

In for responses. Found that my race car had these things in there as well.

Thing is, the regular plugs I bought (Champion 9804 iridium) have a different tip and won't fit the wires I have. I'm confused as to what I can put in there.

NGK ZGR5A and W8CLR+ have been suggested by many. I am thinking about switching to these too if the Bosch +4 is really bad for my engine.

[Sagaris]

http://tlc.howstuffworks.com/family/vehicle-care-spark-plugs.htm

As far as I am concerned, the issue with 4-prong plugs in a performance engine (which allows multiple points to discharge to = less chance of misfire & less plug wear) is that the spark is not exposed to the fuel mixture as openly as with a single prong plug. From a low-maintenance standpoint they are great.

[xwill112x]

Ran them in my m42 for 3+ years no problem. People say the engine runs like crap with them, but I've never seen examples of just the particular spark plug cause drivability problems.

[Cha Ching]

dnguyen, I don't think it's necessarily a matter of the Bosch +4 platinum plug (or any other "exotic" plug for that matter) being "bad" for the engine. I think it's more a matter of the "stock" plugs from NGK or Bosch Supers working just fine at a lower expense. Why spend the money on iridium if there is no benefit? It's just a waste of money.

But that's just my opinion...

[dnguyen1963]

dnguyen, I don't think it's necessarily a matter of the Bosch +4 platinum plug (or any other "exotic" plug for that matter) being "bad" for the engine. I think it's more a matter of the "stock" plugs from NGK or Bosch Supers working just fine at a lower expense. Why spend the money on iridium if there is no benefit? It's just a waste of money.

But that's just my opinion...

Like I said, I had not seen any problem with my car using these plugs. I paid only $4 vs $2.50 ea. The cost is trivial for the plugs. It is confusing to me because many drivers had strong opinions abut using the +4 plugs. I am trying to get some of those guys to give me some definite proofs that the +4 plugs can do some damage to the M20.

[priapism]

I hear they can cause incomplete combustion, but that's just hearsay.

[u3b3rg33k]

You say what's wrong with with them - I say show me indexed +4s.

[blocke]

I heard someone say that our stock coils don't even fire hot enough to utilize those effectively. Who knows if it's BS though

[dnguyen1963]

I heard someone say that our stock coils don't even fire hot enough to utilize those effectively. Who knows if it's BS though

Not sure if this is true, but when I observed the spark plug outside of the engine, the spark moved around the prongs randomly. Not all 4 prongs received spark at the same time.

[xwill112x]

I heard someone say that our stock coils don't even fire hot enough to utilize those effectively. Who knows if it's BS though

BS. The advantage of the +4 or whatever is that the electric current has 4 places to arc from, giving it plenty of paths of low resistance it can arc from or to or whatever. If anything the coils have to work less, as electricty is lazy and the coil will only produce the voltage that it has to.

Not sure if this is true, but when I observed the spark plug outside of the engine, the spark moved around the prongs randomly. Not all 4 prongs received spark at the same time.

QFT. What you saw was the electricty taking the path of least resistance. It changes almost everytime. The only disadvantage to these plugs is you cant easily adjust the gap for optimal conditions.

[dnguyen1963]

BS. The advantage of the +4 or whatever is that the electric current has 4 places to arc from, giving it plenty of paths of low resistance it can arc from or to or whatever. If anything the coils have to work less, as electricty is lazy and the coil will only produce the voltage that it has to.




QFT. What you saw was the electricty taking the path of least resistance. It changes almost everytime. The only disadvantage to these plugs is you cant easily adjust the gap for optimal use easily.

So...the problems with +4 plugs in M20 engine are myths? I still have not seen one post giving definitive proof to those "problems".

[xwill112x]

So...the problems with +4 plugs in M20 engine are myths? I still have not seen one post giving definitive proof to those "problems".

I would say so, I had a 87 m20b25 vert that had them in it, and it had 0 misfires or any driveability issues. I ran them in my m42 car forever, and had 0 issues, So in my experience yes. I wouldn't take them out and buy new plugs when the ones you have are sparking the fuel air mixture in your m20 just fine.

[bernzpeed]

It's all hear say. I'm using them on 2 e30s, absolutely no problems at all.


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