I use Iridiums 'cos they have a brighter spark ... and mine are still going strong after 30000kms (the plugs look like new).
Just take them out every 25000kms and check to make sure there isn't heaps of carbon buildup & check spacing ... if there's a little carbon around the edge, just clean it off with your spacer
I am using the Bosch Super 4 (FR 78 X) spark plugs for my 94 MX, approx $50 for 6 and I have noticed the engine is runninig much smoother. No one usually holds any stock but can be ordered from Sprints.
For F2T Engine I advise to get the ZFR7FIX11 (Why) Because you need a higher heat range coz of the boost build up the more you boost your car the more heat it will produce therefore normal plugs that you buy at shops are only for a standard F2T engine. Make sure next time you buy sparkies ask for 7heat range autobarn has them.
Prepare to bend over for the price though.... My local stores charge $8 a plug plus $10 shipping and that NOT the iridiums. Thats Autobarn, Repco the lot. There is a cheaper plug, that you have to regap yourself that is about $15 for all 4... can't remember the code, but if someone wants them PM me and I'll dig it up.
Mine's a 88 Tx5 Turbo running on Premium unleaded boosting at 10psi. NGK catalogue stated ZFR6A-11 for my car (87-89 model), and ZFR6F-11 or ZFR6FIX-11 for 89-91 model. So the question is can my car being a 87-89 model uses ZFR6FIX-11 Iridium Spark Plugs?
Yes I am using Iridiums too, I figure the less times you take the plug in and out of the head the better for the thread!
Plus they last much longer and dont need to be regapped.
I think Fredio54 touched on this on another thread somewhere...sparkplug gaps.
Most mazdas were meant to have a 0.7 /0.8mm gap, I noticed that post leaded fuel Oz models have 1.1mm (hence the 11 after the spark plug code) I believe that it allows a higher exposure of the spark to the mixture and therefore better burning and lower emissions, which is the reason they specify it for Oz as opposed to general export.
There is one downside to increasing the plug gap : it requires a higher voltage to cross the gap and puts a greater strain on the High Voltage systems.
The Iridium plug, due to its ultra thin point, has a lower voltage requirement (without going to far into electrical theory) the electric field is more concentrated at a thinner point. which means you can run the 1.1 gap with the voltages required to fire a regular plug at 0.7 (approx)
How does that help turbo cars...as cylinder pressures rise, soes does the voltage required to cross the spark plug gap, when you increase the boost over that of the factory, you literally may run out of "volts" to cross the gap and misfires occur.
You can install a coil that produces a higher voltage, or a CDI system which can create higher voltages with a stock coil...or...you can put plugs in that require lower voltages to fire...
No I am not a sales rep for NGK!
However I did have a problem with my ex's KJ laser with a BP 1.8 engine..
it was experiencing breakdown across the spark plug boots(symptom : a stutter of the engine at high throttle/low revs)...I googled it and found that there was an issue with the quality of the insulator material.
I regapped the plugs from 1.1 back to 0.8...the problem dissapeared for a while..but came back...probably as the regular plugs started to wear.
I installed iridiums...problem gone. I could have replaced the leads for Magnecor but never got round to it.
Im getting sick of it and not sure whats going on.
Running 14psi with the flashed Woo ecu, bought the car in march and was fine int itially. Ran for probably 2500km fine then all of a sudden started to develop a miss under full boost.
So changed out my spark plugs and all was good and well.
Then 2 weeks later it started doing the same thing, so I went to a colder plug and went from 1.1mm gapping to 0.8mm.
2 weeks later they are dead too.
Bought some iridium plugs yesterday and installed them thismorning, now its missfiring under high boost all the time, with brand new $83 iridium plugs, have left them at stock gapping of 1.1mm
Im not sure whats going on and its getting annoying.
I can pull the boost levels down a bit and that helps to an extent, but pretty much once the engine is under full load it misfires anyway.
late reply I know, but I had a similar problem which turned out to be a faulty std. fuel regulator. Cylinder 1 was detonating under full boost and would eat the tip of the spark plug!!!!
check your fuel pressure and get your injectors cleaned if you haven't already solved the problem...
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1993 Mazda MX6 4WS
