Why does the Mazdaspeed3 fuel cut so easily?

The test pipe seems to push them over the edge. But that may not be the case for you. What are your plugs gapped at? It will be interesting to see how they look. Report back to us!
Ps i have run my air filters a rather long time without changing or cleaning and never really noticed any difference from doing a scheduled event.
 
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Yeah, 50k miles, it's new plug time. Unless you go with a big catless dp/rp (which would raise boost about 2 psi), you should probably stick with the stock heat range plugs. HT's tune is based on stock heat range. I went with the colder plugs just to provide a little extra protection against detonation. Probably didn't quite need them yet. Usually have to be close to 50 hp up over stock to justify the colder step. But they are not fouling. I drive this car pretty hard. So you could probably go either way and be fine.

One sort of crazy thing is that the colder plugs (in my sig) are readily available at most auto parts stores and are cheaper than the stock range plugs, which seem not to be used in any other applications and are, thus less popular, less readily available and more expensive! If you go with the NGK's (my personal preference, although the Densos seem to do fine), they will come with a huge .045 gap and will need to be gapped down. Either way, be sure to get fine wire iridium center electrode plugs, which are much more appropriate for high boost, high compression, DISI engines. Stay away from the platinums or multi-tip types.

I think I'm just going to stick with the OEM heat range.
So I went to the NGK website and they only recommend:
OE Laser Iridium ILTR6A-8G with a 0.032 gap

The Denso Website recommends only:
Iridium Power IVT20 with a 0.044 gap

Now is the gap listed the recommended gap for that application? Or is it the gap set on the plug out of the box (and it's up to us to figure out what the gap should be)?
Lastly, why is the gap so much different between the two brands?

I appreciate all your help so far!
 
The correct gap is .028 to .032 regardless of the manufacturer. I think you will find that most experienced users of our cars are gapping these plugs on the tight side, typically between .028 and .030. Make sure it is a fine wire tip iridium plug. Manufacturers box these plugs for many different applications, so the "in the box" gap can vary widely and have no relationship to its use in any one particular type of engine.

NGK's one step colder plugs, which I run because of both the catless dp/rp and the HT tune (although neither alone would probably justify going one step colder) actually come in the box gapped at .044-.045 also and had to be very gently and carefully regapped down to .028. With my mods I'm running about 19 psi boost now under load for most of the power band. So a tighter gap reduces the risk of forced induction "blow out" of the spark under load.

And, as pointed out, if I recall correctly from an earlier post in this thread, and consistent with my own experience, you need to be very careful with the tip of iridium tipped center electrode plugs. It is very easy to damage that tip, so avoid any contact with it beyond just barely touching it with your gauge to confirm gap, and never rub anything back and forth against it or it's garbage.
 
The gentleman^ is spot on with each statement and gives thoughtful advice indeed.. I may only add this and its not much. When you adjust your gap, and well you should, it is easy enough to close the gap. The danger zone is when reopening it. You will see what i mean. That was how i broke one of mine. but i was careless with the center electrode also. so maybe start with 32 and see how she is burning.
Now get going^^ because i want to read your results!
 
I can't remember if I posted this in this section or not but I'm having a partial throttle issue that sounds like it may be fuel/boost cut... I have a Cobb AP with protune but I"m running a GReddy EBC to control boost... when I get on it and start to pull (not WOT, by the way) my car starts to build boost (it's set to spike at 20-21psi and taper to 17-18psi) around 13-14psi under part throttle the BOV (in my case HKS recirculating) starts to flutter and release pressure and obviously the car bucks a bit cause it's losing boost. This is with my foot on the throttle and only under partial throttle like I said.

My mods are listed, the car is at ~27,000 miles, haven't changed the Cobb SRI filter and haven't touched the plugs... but I AM definitely 50+whp over stock.

Any suggestions? I can't seem to figure it out personally and don't much feel like paying at most $380 for a re-tune just for the guy who tuned my car to look at it again (although he did say that if we can't find the issue with the current setup he'll figure out a way to make it work.)
 
Bucking is a bad word. How did you Tune. Boost by throttle pos or boost/rpm? You might be having surge pressure trying to stall the turbo. Turn the boost down till you sort this out. I am no expert by any means but it sounds like some boost and either a wastegate or boost reference not allowing blow off quick enough.
I am just guessing form what you have written. But if that is the problem it might be very not good for the motor. Did you recently install the greddy profec? after the Cobb?
 
My experience is that valve flutter 'which is not a bad thing at all' will NOT cause jerky ness. And when underboosting/partial or reducing boost by relief should just make less power. Its like the car just sighs instead of sounding angry.
 
The EBC was installed before I had the car tuned. I didn't tune it myself, I had a professional tuner do it and he said having the EBC helps, he's tuned many Mazdaspeeds before mine, I'm definitely not going to be messing with ATR because I don't know what I'm doing when it comes to tuning myself... I just know basics. I don't know how he tuned the car, and bucking isn't quite the right word, it's just boost cut as far as I can tell, but it's confusing because it's only under part throttle, under WOT the problem doesn't exist at all.
 
what rpms? My tuner spent hours tuning out cuts. throttle position did not matter. I believe it was caused by the increased flow and no back pressure on the turbo.
My issues were 3,4, and 5 gear. I had a cut around 3000 rpm and another at around 4800 i believe. I will write him and ask him what he suggests.
What does your tuner say about this. My cut was nasty, i am suprised the motor held up. But i have running 21lbs max for a full year and she is ok. Still need an ebc and some more tuning. I sure hope you can resolve this! i would try to get back to the tuner and create the problem while data logging. Good luck
 
Thanks man! That sounds like a similar problem and I'll do so, I believe my cuts are around the 4800 mark too, because it happens every time I'm accelerating to get onto the interstate, and I usually accelerate in 4th/5th gear when getting onto the highway. Mine isn't so bad, it's just annoying as hell!
 
Well i hope i helped a little, i am no tuner probably like you. But i try to pay attention and learn what i can. After my tune on the cp-e standback one of the first things he told me was i need an EBC. So good call on your part.
Please let me know if you make progress. Or not even. I might learn something.
I will write my tuner today after football and ask his advice about how he fixed boost/fuel cut.
One thing of note was my fuel pressure and injector duty cycle was always good and that was a relief for me.
eric
 
I haven't ever noticed that my fuel pressure dropped terribly but I probably will upgrade the pump nonetheless just to be safe and for the benefits of the increased pressure and higher consistency it would provide. My tuner down here told me the EBC would make tuning it a lot easier than having to mess with the ECU boost targets through AccessTuner. I e-mailed him today but they're not there on Sundays so when he gets back to me any advice he has I'll share on here otherwise give it a few weeks when I actually go back to get the re-tune and the bugs worked out and I'll share my results then. This was a revelation for me haha didn't ever guess it would just be boost/fuel cut due to the tune, I thought something was wrong with my BOV at first but that wasn't the case and so I tried a few other things as well. But this seems to make the most sense.
 
The reason i mentioned the fuel pump pressure and duty cycle is because, that was my biggest fear before i could read any data. I was mostly rich and we were pulling fuel. For now save your money. Unless you are not holding above 1300 psi at WOT and then only if your af/r are dropping off to lean condition.
It's interesting you mention the BOV.
Because at your first post i was thinking you are not relieving boost properly. But your tuner will know best. its all about the data these days.
I have not received any email back from team_redline yet but it is Sunday so we shall wait and see.
good luck of course
 
Sounds good, my pump will see 15-1600+ just daily driving (using the DashHawk to monitor it) So under WOT it should be just fine. My AFR's run perfectly cruising and run rich at WOT to about 12-12.5 which was how it was set by my tuner, but daily driving I see a constant 14.5-14.9, sitting at 14.69 mostly... which is pretty much perfect. The BOV I don't think is the issue but I'm trying to sell it anyway to go Turbosmart instead, although like MSMS3 I may just run the stocker for a while since it seems to be a pretty decent unit until you get real nasty.
 
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14 9 is a bad #! But the most important will be af/r under load. This is his quick response.
"You were getting boost cut cause it was seeing over 18 psi tooo long. It is boost cut cause your computer is programed to cut out at that boost level cause its not tuned after that. We had to trick the computer to think its boosting less than 18 psi at all times. We did that by the boost cut option on your standback and then for safety measur i minused it on the map sensor so it wont see the 22 psi you were getting. So when you got up in the rpm when it was at 18-22 psi i made it see from 15-17 this was so it wont hit boost cut cause it thinks it is on a lower boost level. But remember he has to tune it with the fuel to compensate for the trick. So when it is at 22 psi the computer thinks it's at 17 make sure he tunes the 17 psi for 22 psi and watch the afr to make sure he is safe. Cause if he puts it at 17 psi it will give fuel for 17psi and that will be too lean. HE has to make sure it has the fuel for 22 psi, a good 10.9-11.6 afr would be good depending on what he is trying to do. If its stuck at the 17 psi afr on the 22 psi it will read extremly lean like a 12-13 afr. Also remember to tell him to do the timing also." I hope this helps some
eric
 
Well in my case I'm using the AccessPort and AccessTuner to have the car tuned... that program is able to set the boost targets and cut limit on the stock ECU within the software itself, so that's not my issue. Not to mention I have my cut problem at 13-14 psi maybe even less, depending on the circumstances.

How is my 14.9 a bad number? I don't see it constantly, the Dashhawk readings just fluctuate because they update constantly, and like I said I see from 14.5-14.9 hovering around 14.7 mostly, which would be the "perfect" mixture, I've even read that it's actually a tad rich at 14.7 so I'm not too worried about my 14.9.

What are your thoughts/what's your reasoning? Remember these are A/F ratio's.
 
I was just quoting the letter i got back from my tuner Team_Redline asking how he was working around my cut. We were using an innovate with a bosch sensor.
I am sure you can smooth the table. with the cp-e we were able to run live data on four tables at once and a sepearte readout for the Innovate.
As i said i am no tuner but i did want to ask him what he did. Can the access port record data for review? My car was very rich at times under the stock tune and bolt ons.
Has your fellow gotten back to you yet?
I hope you are able to get it sorted to your liking. Sorry if i am causing confusion.
GL
eric
 
Well he just said the best I can do is bring the car in so we can figure it out first hand, but I have to make a note to negotiate and either get it done free or deeply discounted, I shouldn't be paying for a re-tune to get rid of an issue that shouldn't be there after paying for a professional tune once. AP can datalog as well as the DashHawk.
 
He is probably right you gotta feel it out with the car in hand.
Kinda like me trying to help over the forum. I have probably caused more confusion, even though i have the best of intentions.
I bet it will be something simple. Keep me posted!
 
Great info.... Looking for similar help.

Reading through this thread has been very helpful. Thanks to all for the great discussion and exchange of information. I am trying to help a friend (with a Speed3) with his tune and I think he is running into the same problems you all are discussing. He recently purchased an AP and loaded the Stage 2+FMIC 93 map. His mods are Cobb SRI, PG Turbo Inlet, PG FMIC, CorkSport Test Pipe, HKS SSQ BPV, HKS Hi-Power Catback Exhaust, and he just installed ITV 22's (he checked the gap before install). He has had all these mods and no tune for at least 6 months, so he got use to his car doing strange things under a variety of load conditions. After loading the Cobb and flashing the map he said that the car was running better, but there was still significant KR. I took it for a ride last night and my impressions were;

1. Much smoother than last time I drove it (5-6 months ago)
2. Pulls hard (to the right if you are not paying attention, torque steer almost caught me sleeping the first time I jumped on it) It was a little bit of a wild ride until I got use to being in a FWD monster again
3. Loosing power WOT around 4.5K, should pull MUCH harder to 6K My current thinking is that he is hitting fuel cut when his car builds 19+ lbs of boost. I think he agrees and said as much last night, but we weren't sure if it was boost cut or fuel cut. After reading a bunch I am leaning (pun intended) toward fuel cut. The big question is, what is causing it. I think it may well be a combination of needing new fuel pump internals, and something in the tune needs to be adjusted, but what?
4. Also loosing power/knocking under less than WOT conditions. Less predictable/repeatable. Not really sure of the cause of this, but I suspect this is also a problem with the relationship between his tune and his mods. Since it is happening under less than WOT conditions I am not as concerned with this since the engine should have no problem protecting itself.

Possible solutions:
1. Tuning out the problem I think this is going to be the best way to go. Fix the tune rather than put a Band-Aid on it.
2. Fuel Pump internals Another friend's idea, and I am thinking he is onto at least some of the problem after doing a bunch of reading, some of it right here in this thread.
3. Using a different map (currently on Stage 2+ FMIC IIRC) Stage 1 maps would drop the boost target and that might fix the problem, although I think it would only be masking it.
4. Some sort of electrical/mechanical fix (EBC, MBC, Boost Cut Defender, Fuel Cut Defender, etc....) Band-Aid, not a good final solution, but could be added for another layer of safety
5. May be temp related. I live in Chicago and he has only had the AP for a few days so it has been cold the whole time. However, I am not haveing the same problems with my wifes MS6 running a Cobb Stage 2+TIHSF tune in the same weather.

Here are a few logs. I tried to name them in a way that makes it easy to tell what you are looking at. It was pretty cold (like 12 deg) when we made these logs. Questions, comments????
 

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  • Cobb recommended 2nd gear 1500rpm up to 100gs mass air pull.xls
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  • log with some KR around 30 sec mark.xls
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  • 4th gear WOT pull 3.5K to 6K.xls
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