My Denso Iridium after 38,000km

[fabianyee]

Originally posted by kevster30@Jan 24 2005, 10:23 PM

Bro,

What exactly did you gap it to?

no exact measurement since the wear oso not even... but normally, for BMW engines, gap should be slightly narrower then the pregap of 0.8mm...

from Brendan Purcell's website http://www.esatclear.ie/~bpurcell/318isengine.html

it stated 0.027" which works out to be ~0.7mm

but I pakai hantam je... but works

 

[kevster30]

While servicing my ride today, I decided to pop out my iridiums and take a look. Measured the factory preset gap at 0.90! BMW recommends 0.80 so I adjusted them accordingly, and WHOA! Nice improvement in my low end torque delivery!

Would never have believed it if I hadn't tried it..............Thanks Fabian!

 

[fabianyee]

a mere 0.1mm makes a difference in the sparkplug's firing characteristic....

Now we know why proper racing teams spend countless hours setting up a car/bike for racing....

 

[Mouse]

i heard if our original OEM spark plug is 4 legged, we must change back to 4 leg plug (brand doesn't matter), if we change to normal 1 leg plug, our engine will encounter problem like misfire and increase fuel consumption, it that true? any E46 member using 1 leg plug with no problem?

 

[chairoger]

Interesting stuff.... Never thought of it that way.

 

[Jules]

i heard if our original OEM spark plug is 4 legged, we must change back to 4 leg plug (brand doesn't matter), if we change to normal 1 leg plug, our engine will encounter problem like misfire and increase fuel consumption, it that true? any E46 member using 1 leg plug with no problem?

why you think this is so? care to elaborate?

 

[Mouse]

why you think this is so? care to elaborate?

i was checking with rapco malaysia which is dealing in NKG, Denso and various accessories, this is told by the sales guy that if our original is 4 legged and we change to 1 legged then our engine might developed problem. i am not sure how true, that is y i need verification from u guys.

 

[fabianyee]

it could be due to the assumption that the single legged plug would be longer than the 4 legged ones.

If it is, then it may not have enuf clearance between the leg and the piston.

 

[omegaoracle]

great info.. never knew the gap made so much difference

 

[DanPromote]

I took out my NGK Iridiums & changed to Denso 4-point plugs... didn't notice any diffrence, but I noticed there is a big gap on the NGK compared to its original position. What's the ideal distance between the tip?

 

[Daniel]

Let me include further info on this plug gaping topic:

The simplest way to do it is to buy a gapping tool (usually a disc) with many different sizes that you slide between the electrode and cathode. I think if you wanted to gap them larger then sliding a larger spacer in would stretch it properly to size, and if you wanted smaller then squeezing the electrode down onto the properly sized disc would result in the desired gap.

If the gap is too big you get what's called flame out. That's when you don't make a good spark at high rpm because your coils and wires see to much inductance and the voltage drops. The larger the gap means the more voltage it takes to cross it. If you run a smaller gap you can go to higher RPM without changing coils or wires. However you need a good spark to create good ignition. So the idea is to find a gap that combusts all the fuel and still works at the redline. Old plugs usually feel shitty because of the gap. You'd be surprised how nice your car would run by just adjusting your gap.

Back to the iridiums, be careful if you adjust them. Try not to touch the centre electrode at all. Mine were perfectly gapped out of the package. Iridium is very hard and doesn't melt like the old copper plugs did. The idea is that they require less servicing and because they are pointy they require less voltage to cross the gap. I won't get into the physics of it but trust me it works.

This link may help with deeper info on denso plugs:

http://www.densoiridium.com/index.php

 

[trex101]

Don't get the 0.4mm iridium, it's not design to last more than 40k.

Check this link out.
Technical bulletin

 

[Daniel]

er.... how long would one expect from a set of plugs?

 

[chairoger]

Normally change mine every 10k together with oil change.

 

[Mouse]

Normally change mine every 10k together with oil change.

bro, mind to tell us what plug u r using and how much it cost? u change every 10K, walau, u must be a car lover and sayang your car more than your gf . previously using bosch super 4, i just brought NGK laser platinum and trying it out next service. i think most likely i will change them every 30K instead of 60K as recommended. i also sayang my car........

 

[chairoger]

Hehe Using Beru Ultra X......compare to other wear n tear n repairs,
oil change + oil filter + spark plugs change all cheap cheap one.

 

[MONTOYA]

Which model of the irradium are you having. Power or tough? the "tough" is suppose to last 100K. the power is 30-40K.

 

[koryong]

... but normally, for BMW engines, gap should be slightly narrower then the pregap of 0.8mm...

Is that the recommended gap for all Beemer models or just the iS ?

Also if new plugs out of the box are not pre-adjusted to this gap, I really wonder if our mechs would adjust them before putting them in ...

 

[Mouse]

anyone know where to get bosch platinum +4 plug?

 

[fabianyee]

Not not what gap most plugs are pre-gapped to but most mechanics wouldn't bother to check the gap, the just replace them..

I don't think there's significant harm for the engine just that u don't harness the full potential of the plugs if they are performance plugs.