Hey guys i bbeen throught like 4 sets of spark plugs.For some reason,at mid to high rpms i can feel the the spark plugs or electrical system liek breaking upp.I gaped them also,but still the same chatter.Does anyone have a clue what this possibly could be.Its getting really annoying.
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Spark Plugs
- Thread starter boost3
- Start date
What kind of pulgs are you using and how much are you changing the gap. You may be damaging the plugs when you gap them. Are you throwing any misfire codes or showing any knock. I think you would want one step colder plugs gapped to around .028 with your setup. Denso's come set to that gap. What do you mean by chatter?
SharkDiver
Member
- :
- Speed3
I would stick with denso or ngk plugs...I use ngk and just installed a set of 1 step colder plugs today.I put ngk's in all my cars and bikes.
http://siteground207.com/~protegeg/product_info.php?cPath=160_403&products_id=1295
i was checking that out.heard it will help with my problem but its alot of money
i was checking that out.heard it will help with my problem but its alot of money
FrequentFlyer
Member
- :
- 2008 CWP Mazdaspeed3
Turbocharged motors tend to be rough on plugs, but I highly doubt the ignition system in the MS3 is incapable of handling the task. Most of these new motors with coil on plug setups have plenty of juice to ignite the fuel/air mixture. I'd also have to question your theory that at high RPM you can actually feel the spark plugs or electrical system "breaking up". The problem could lie elsewhere. You've been through 4 sets of plugs. When you took them out, were they in bad shape? If not, you're wasting your money on fancy, overpriced HKS plugs. Denso or NGK OE replacements, a step colder if needed.
yes its true, very soft electrodestry the denso's since you won't have to gap them. gapping iridium plugs is hard to do correctly.
I think gapping will be the secret here not the iridiums which are in the car now. I have heard the iridiums wear quickly on boosted cars when playing with timing. I will regap stockers and reinstall just for fun. When I pulled stock at about 20000 they had some wear at electrodes and looked a tad rich.
- :
- 2007 MS3
While I had the intercooler off for my aborted wastegate actuator upgrade, I pulled a couple of the plugs for the heck of it. Wow are those tips tiny! They aren't much thicker than a heavy sewing needle. I would be afraid to try to change the gap on those. I know damn well I would slip and ruin one.
Yes, it can happen I hear! I had alot of sputtering in the middle area of rpms under acceleration and so, tightened up the gap and things improved, actually went away after a week or so. kinda weird how the car adjusts to things. Now with fuel pump I just have boost cut again. I agree the ignition should be fine. Mid life are you talking about the stockers?
07Speedfreak
Member
- :
- 09 Subaru WRX
Is it worthless to change the plugs if you're stock ? I already have the step colder plugs brand new in the box for when I was gonna run the tbe, but just never installed them.
- :
- 2007 MS3
Mid life are you talking about the stockers?
Yes. Don't tell me they shouldn't have tiny little tips on the center electrode. I do not want to spring for new plugs right now.
Sorry to alarm you. yes they are tiny. the iridiums are tiny too. and very soft i have come to understand. Speed freak, no need save the cold plugs for the mods. They are kinda like soft compound tires, do not last that long and the performance advantage may only be realised by pushing the car harder< my opinion is all
freebird_78
Member
- :
- Mazdaspeed 3
Actually, Iridiums are much harder than stock electrodes. This is why OEMs rate them for 100K miles, because the electrode is so hard that it wears much less quickly than comparitively soft copper or steel center electrodes.
The hardness is also what makes them delicate to gap. They are so hard, the electrodes are brittle and therefore relatively easy to break.
The traditional rule of thumb for colder plugs is that for every 75-100HP gain, go down one step colder. TBE will obviously not get you anywhere near that power, so colder plugs are a waste, IMO.
That said, they can, theoretically, help aleviate some knocking if you already have an issue. The drawback to going with colder plugs is that they will foul, and you will need to change them much more often.
Gap affects the spark "heat". A smaller gap yeilds a cooler, but more reliable spark. The plug will be less likely to blow out with a smaller gap. DO NOT change the gap by more than +/- 0.008" from the out-of-the-box gap. Changing the gap by more than 0.008" changes the geometry between the center and ground electrodes, as they will no longer be parallel to each other, therefore altering the arc.
The hardness is also what makes them delicate to gap. They are so hard, the electrodes are brittle and therefore relatively easy to break.
The traditional rule of thumb for colder plugs is that for every 75-100HP gain, go down one step colder. TBE will obviously not get you anywhere near that power, so colder plugs are a waste, IMO.
That said, they can, theoretically, help aleviate some knocking if you already have an issue. The drawback to going with colder plugs is that they will foul, and you will need to change them much more often.
Gap affects the spark "heat". A smaller gap yeilds a cooler, but more reliable spark. The plug will be less likely to blow out with a smaller gap. DO NOT change the gap by more than +/- 0.008" from the out-of-the-box gap. Changing the gap by more than 0.008" changes the geometry between the center and ground electrodes, as they will no longer be parallel to each other, therefore altering the arc.
Very good info about geometry Free. Thank you. bear in mind that a turbo back will allow more boost which also will increase HP alittle although you are moving out of the compressors effiency map I think. Do you know what the gap is from ngk as compared to the denso. i thought I had seen someone mention that there is a significant difference out of the box, and the denso was much tighter. From stock, just for reference, the car has gone from low 14s to to 13.74 with IC to 13.4-13-5 with tbe and tires and no driver mod. I do not know how many ponies that equates to to. I have a friend who dynoed a different car and he mentioned the iridiums picked up power right away but after a short while they actually dropped off. He mentioned they are good plugs but seem to wear quicker with alot of boost. Mine are at what I would consider a pretty big gap. What is the recommended gap for our car? Thank you sir
freebird_78
Member
- :
- Mazdaspeed 3
Ok. I've done a little writeup on this subject on one of these boards, just can't remember which.
Anyways, the jist of it was that the gap recommended by Cobb (0.026-0.028") was specifically for the Densos. This gap does not apply to any other plug. Reason being is that Densos are the only brand that makes a 0.4mm center electrode. NGK and most others use a 0.6mm center electrode. Because of this they all have different recommended gaps, most non-Densos being fairly close to each other. Densos should come 0.035" out of the box, whereas NGKs should come 0.044", my Autolites came in at 0.050". Using my previous post as a guide, you can adjust from there.
As far as power goes, I doubt there are too many people making 75-100HP above stock. I also find it hard to believe that any plug swap will make any meaningful additional power. The exception to that is if the ones being replaced are FUBAR, which considering your car is at most 1 year old and came with OEM iridium plugs, I doubt. Possible, but not likely, but even then, you won't MAKE power, you just lose less.
FWIW, I'm running a CP-E catted DP, ETS TMIC and Cobb SRI. I switched to -1 colder Autolite XP Iridiums on a recommendation when I used to have the AP because I am/was seeing knock. Can't quite say whether the plugs quelled any of the knock, but I can say for certain that I've learned that my knock is 100% tied to ambient temps. >90degF and I guarantee knock. If/when these plugs foul, I will replace them with the OEMs I took out.
Anyways, the jist of it was that the gap recommended by Cobb (0.026-0.028") was specifically for the Densos. This gap does not apply to any other plug. Reason being is that Densos are the only brand that makes a 0.4mm center electrode. NGK and most others use a 0.6mm center electrode. Because of this they all have different recommended gaps, most non-Densos being fairly close to each other. Densos should come 0.035" out of the box, whereas NGKs should come 0.044", my Autolites came in at 0.050". Using my previous post as a guide, you can adjust from there.
As far as power goes, I doubt there are too many people making 75-100HP above stock. I also find it hard to believe that any plug swap will make any meaningful additional power. The exception to that is if the ones being replaced are FUBAR, which considering your car is at most 1 year old and came with OEM iridium plugs, I doubt. Possible, but not likely, but even then, you won't MAKE power, you just lose less.
FWIW, I'm running a CP-E catted DP, ETS TMIC and Cobb SRI. I switched to -1 colder Autolite XP Iridiums on a recommendation when I used to have the AP because I am/was seeing knock. Can't quite say whether the plugs quelled any of the knock, but I can say for certain that I've learned that my knock is 100% tied to ambient temps. >90degF and I guarantee knock. If/when these plugs foul, I will replace them with the OEMs I took out.
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