Ok, I got the ECU behavior from MAZDA Engineering!!!

"Throttle never closes unless the engine is shutoff. If engine shutoff, throttle closes momentarily so no fuel can go into engine and cause diesling, then opens and stays open.
In the case of coasting downhill in gear, throttle stays open, but injectors turn off. acts like an air pump."

Edit: "Throttle never closes unless the engine is shutoff. If engine shutoff, throttle closes momentarily so no air can go into engine and cause diesling, then opens and stays open."

What does fuel going into the engine and throttle closing have to do with each other? Dieseling? Are they talking about the extra special carburator model of the Speed 3?

If the throttle stayed open during coasting you would not see high vacuum readings in the manifold so ummm ... who is this person that replied to you? I'd love to ask them more "engineering" questions.

EDIT: I meant no air can go into the engine, not fuel. Sorry for the confusion.

The first statement was just in response to my question about when does the throttle plate close. They were just saying that the only time the throttle plate (air flow control) closes is when you turn off the engine. It closes to make sure the engine stops, then re-opens. I believe that is that noise you hear a few seconds after you turn off the car. It's the throttle plate re-openning.

The second description applies directly to my case. I was trying to rule out detonation or preignition and this confirms that it couldn't have been detonation or preignition that broke my rod since the injectors were shut off while I was coasting.

I called the customer service number for MAZDAUSA, 1-800-222-5500. They really can't guarrantee they will be able to get answers for you, but they try. They are just customer service reps and they pass your question to the Engineers. If they feel the information isn't proprietary, they will respond.

Yes, the injectors do close during coasting conditions. It is called and over-run fueling state. The throttle plate does not completely close during coasting - correct - but it is close to being closed.

Detonation is never a concern during coasting but damage done due to detonation can fatigue and deform a rod that will let go under high engine vacuum. Under vacuum the rod experiences the strongest "pulling" forces on its beam. Think of the beam as a very high strength spring. After enough cycling, if not designed for the load it is handling, it will fatigue and fail.

It seems to me that detonation is not a factor at all... of all the posts I've read from guys who had a rod break, and tore down the engine afterwards, there was never evidence of detonation, i.e.: pitting on the piston crowns. I cant say I've seen even one engine with a broken rod where anyone saw any evidence that detonation had anything to do with it.

Any of these engines have any signs of crankwalk?

My personal opinion. No evidence or fact to base it on.

Is that the problem is more likely to be a pre ignition event rather than detonation event.
Where the mixture is ignited too early in the stroke by something other than the spark plug, by lets say "glowing carbon deposits".
This type of event may not be picked up by the knock sensor and would produce massive extra force on the rod. Enough to throw it through the block.

I am not saying this is the cause, I am saying it is much more likely than knock/detonation, because of the lack of evidence of such knock/detonation.

You are right, the knock sensor will never pick up a pre-ignition event, since there is no high pressure spike. I have a short block in my garage right now with a bent rod with zero signs of detonation. I will have the block torn down soon, it might be crank walk, but more than likely it was a pre-ignition event. I will know more soon.

It has been my belief for a long while that preignition is why most MZR motors blow.
That is why the first thing I did when I got ATR was to lean out the AFR.
Leaner = less carbon.

A catch can would help in this regard too. But I dindt go that route, as I want quick and easy back to stock just in case.

Having said that it may not necessarily be carbon deposits that are causing the preignition, but at least that would help minimize one possible cause.

I also tend to think the heavy carbon build up is a major concern since it could easily provide a pre-ignition initiating condition.

Which is why I am using lots of Meth and have a OCC that I am going to install...

Noobie with a question: Can pre-ignition occur while off-throttle and the injectors turned off? If it does occur, will it cause the rod to break right away or would it weaken the rod over time like detonation would?

A pre-ignition event will kill the rod almost instantly.

The only way I believe a pre-ignition to occur while off throttle would be a leaky injector, or another fuel source i.e. oil being ingested. There is no engine that can live through a pre-ignition event, but most modern engines can live a while with detonation, but, and this is a big one, once the engine starts making more than 1.5 - 2 horse power per cubic inch it becomes very critical to keep the detonation at bay. Even with very short detonation event there will still be the signs, tops of the pistons will have some sandblasting effect, and metal flakes embedded in the porcelain of the spark plug.

From what I understand, pre-ignition is far more damaging to the pistons than detonation. A single pre-ignition event usually destroys the piston and/or rod on the first event. It is said thet it blows holes in the pistons, but I guess a snapped rod is just as good. I wondered if I had a leaking injector, but they can't test them at the dealership, so who knows. I also wondered if it was oil detonation, but there was no sign of oil ingestion according to the tech.

yeah I agree that preignition could definitely be causing this. We all have seen how the pistons usually have a ton of crud on top of them in a lot of the pics that have been posted.

I havent done meth or an OCC, I want to stay warranty friendly, but I do run a can of Seafoam/Deep Creep through the intake before every oil change. I had GREAT success with this stuff on a project car I had a while back.

Reminds me, I want to start replacing the PCV valve every 10k or something like that...

One thing though... wouldnt the overly rich condition that contributes to the extra carbon buildup, also do a great deal to cool things down and keep the carbon from getting hot enough to preignite the charge? Sorry if thats a dumb question.

Also, Havent we had people throw rods that HAD meth and catch cans?

You are right....The pre-ignition event can burn a hole in the top of the piston as well as creating a massive amount of pressure in the combustion chamber over a long period of time. I think why we do not see the holes in the tops of the piston is maybe the thermal inertia of the piston will with stand the heat long enough to bend or break the rod before burning the hole in the top.

What did you plugs look like?
Was the car runner a little hotter than usual?
Do the cylinder walls look scuffed?

I would think that a well-designed OCC wouldn't void your warranty, since everybody knows they are better for an engine than a PCV system is. But Mazda's job is to cut their losses, so... Besides, in California at least, you have use an OEM PCV system to get through a smog check. The CARB insists that all those stray fluids and gasses get burnt in the engine, instead of shed into the environment. Nevermind if you put the grizzle from an OCC in to your used motor oil tank and dispose of it responsibly, they mandate PCV's. Period.

It's been said before, but this motor wasn't designed from scratch for direct injection, it was an add-on. I don't know if they got it quite right yet, but I do know that revisions to the PCV system have been made since the DISI motor was introduced. Still, I'm amazed about how much mystery junk fills up an OCC that would otherwise be dumped back into the intake manifold - without the benefit of fuel detergents to clean it up.

As for engines with methanol systems and OCC's installed to combat the problem blowing up too, well, apparently it's not enough.

One product I've had good luck with in the past was Mopar Combustion Chamber cleaner. It's specifically made to clean carbon from the combustion chambers. Works a bit differently than Seafoam, which I'm not fond of, but if properly used it does dissolve carbon buildup very well. You don't put it in the fuel or oil, you spray it into a vacuum port with the motor just runnning a bit above idle, and let it sit for 3 hours, then drive the car hard to blow out the result. Lot's of cat-clogging smoke will be produced, but it really did wonders on my previous cars.

I'm hesitant to recommend it on these motors though since it was formulated to be sprayed into a throttle body that the DISI motor lacks, but I payed a shop to visually "scope" the cylinders and they as were clean as an OR. Much different motors though. And I spent a lot money replacing the cat's on my last car because the CEL was throwing a failure code, so it would't pass smog. Ran great though, passed the sniiffer test with ease, and the engine had zero carbon buildup in the cylinders after 85K.

Point being, if pre-ignition is actually happening from carbon buildup, this stuff WILL remove it. But I take zero responsibility if it does more harm than good on your car though.

What I wouldn't do is use a piggyback ECU that leans the AFR out in any condition. I know from my shitty mpg that the stock ECU just dumps fuel to stop detonation. But how they got a motor certified to dump so much un-burned fuel into the air is a mystery. And "Italian tune-ups" just make it worse. I haven't even pulled a spark plug on my car yet, it only has 10K, but I'm concerned.

I'd like to solve the problems without voiding the engine warranty, and if running too rich too often is the real culprit, shame on Mazda. Personally though, carbon buildup is an especially bad thing on pressurized motors, so a plug check and maybe a dose of Mopar CC is in order.

And I like the idea of replacing the PCV every year, even on a stock car, since that seems to be a constant issue. At least on the pre-2010 versions, which have a different ECU and yet another revision of the PCV system. It's probably a better combo, but I can't legally change them in my state. Besides, the ECU is integrated into what used to be called the "body computer," so it might do more harm than good. Plus, it would obviously void the warranty, and make it impossible to pass a smog check, since the ECU is essentially married to the VIN number, which their machines look for right away.

I agree with ASIC_BSEE that it couldn't have been pre-ignition that broke the rod as he says he was coasting with his foot off the throttle when it popped, so no additional fuel would be sprayed into the cylinder then.

I could see carbon deposits being of concern if he were ripping around in high boost and cylinder temps got hot enough to cause the carbon to glow, which could ignite injected fuel before the spark does.

Just to be clear was not suggesting that ASIC_BSEE's case was caused by preignition directly while engine braking. Impossible.

Could there have been some damage due to pre ignition and then the rod gave way under the tension of engine braking..... maybe.

All I did was post my theory on why I think "most" MZR motors blow, it was not related to anyone's particular case.

Personally, in ASIC_BSEE's case I would suspect some kind of flaw in the rod metal.
Just because it broke in a different place than the other rods I have seen pics of, further down toward the crank in a thicker part of the rod.
It may be too mangled to tell, but I would be interested to see if there is evidence of bending on that rod.
Or evidence of a flaw in the metal structure.
Again, just speculation from looking at the pics.

good stuff

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I got the word that the short block was ordered and they should have an ETA this week.

I owe my dealership a HUGE thanks for all they have done. They really have gone out of their way to diagnose my car and get this whole thing resolved.

That's really good news, very happy for you.

How much did that extended warranty cost you, and what company is it?

ASIC_BSEE.. did u have a tune?

A friend who has a MS3 -07 was called in to Mazda to have his ECU reprogrammed.. some update. One of the update he was told was a torque limiter in gears 1-3, some early -07s doesent have this, all later models should have it. That could be a problem maybe if u dont have it.. just a thought... anyone heard of this?

Looking through these pictures here ... always the same story - the rod get sslightly tweaked so now the beam is not straight - or it was never completely straight stock. After this the car continues to run but the rod is loaded off axis on every stroke works the metal ... kind of like bending a wire back and forth. This can last for a while but eventually the rod fatigues and snaps.

Thing is that most of the time no one will notice a slight bend in the rod and the rod will let go at an unexpected time after it's been worked enough. The rods seem to be quite malleable from that point of view. Definitely a forged metal - not that it matters at this point.

Has anyone noticed this type of a change in ATR's stock style maps?

The extended warranty costed $1960.00 and it is through Automobile Protection Corporation (APCO).

Stock tune, not sure which update it was, but I had the fuel pump TSB done a while ago and they did a reflash at that time.

Wow that's expensive, but it sounds like they came through with great service. Thanks for the info.

Details about how it happened
 

I used to drive my MS3 like a rent-a-car:drive::drive:, and I have never had an issue with it. I already spent a lot of money on parts including a gt3076r, and I am waiting for the fuel pump to arrive, so I can start putting stuff on and tuning. I am really worried about blowing my engine up, and I am wandering if the problem that every body that blown his engine had good lubrication. Did they change the oil when they were supposed to? Were they monitoring oil pressure? Was the engine receiving enough fuel? Every body is talking about what happened, but no one have given those details yet. When I say monitoring I am not talking about a dash-hawk. Did anybody have gauges to monitor that? Did they look at them, or they just had them because they look cool on the dash? :ugh1::ugh1:To be honest I have a lot of things to install, and all I have is a boost gauge for right now. I am wandering if a good stand-back tune would prevent me from having that issue.

I just read that entire ptp thread on oil hydrolocking the motor yada yada.. any verification on that? or anything? I just wanted a reliable fun DD with a bit of power but it potentially looks like a big headache coming my way

In all honesty, keep it stock and if anything happens, Mazda can warranty it.

If you want to modify it, get the MSCAI2, MS catback, MS spings or coilovers and be happy with it. It is a fun car in stock form.

If you feel really brave, add a Cobb AP and get a tune done. It will be reliable and fun to drive. For dealership visits, uninstall the Cobb AP and TAKE THE UNIT OUT OF YOUR CAR.

The biggest thing is to get a good tune done when you add a modification. Even with an intake, you should at the very least, calibrate your MAF sensor.

That's my opinion.

I hope I can have a solid warranty on a used version, not get owned if they find out the car's been previously modded or some shit

Check this picture out that my friend took of my blown MZR engine

http://farm3.static.flickr.com/2662/...302b014e_b.jpg

This really sucked but my cars back up and running now. running better than ever!

^ Details on how it blew, etc etc?

I was previously running and AccessPort. Cruising at 60MPH on the highway just started seeing smoke and then a pop. Pulled over to find a large puddle of oil on the ground and me stuck on the side of the road. After inspection of the engine by friends we found the engine running to lean. The turbos exhaust housing was all white and powdery. Spark plugs completely fowled.

My engine met all the requirements for stage 1 and 2. from speaking with my friends i realized that not all OTS (off the shelf) maps are created equally and that due to the altitudinal conditions my car is under it will directly affect my A/F ratios.

We have a tuner that will be coming to Hawaii to tune my new engine and goodies when they arrive!

Were you cruising on flat ground or up/down a hill? Was it set on cruise control? Also, when you saw smoke did the car stumble at all? Was it a huge road covering cloud of smoke?

Did you have a fuel pump installed and noticed any weird issues with the car prior to the blow?

Thanks for the info, just doing a bit of a survey of blow-ups - it's a bit of a hobby :)

to further elaborate on what i mentioned... for the past two days I've been noticing bellowing white smoke coming from my tail pipe. This happens mostly at idle. I'm due for a PCV valve change and definitely a oil catch can. I also looked into the PTP stop smoke fix and I'm still smoking. It went away late yesterday but I'm still concerned because my new engine has less than 4k on it now. Unfortunately I didn't buy this car new and at 32k it blew. Who knows what the previous owner had done to it. I suspect it had an AP on it previously because there was a cobb sticker in the engine on the radiator support when I got it. car was bone stock though.

I'm still not running my AP though.

cruising on a flat road, no cruise control and no stumble from the engine when it happened. huge amount of white smoke when it did happen.

unfortunately no fuel pump internals or pump installed due to it being unavailable. I'm ordering the PTP internals though.

no worries. Glad someones taking the initiative to get to the bottom of these issues.

Not sure if this is important or not...but according to Mazda (dont ask how I know) this issues is directly linked to Hydrolocking due to Too much fuel. How many people had upgraded Fuel Punp/Internals? I would still think is a hole in the ECU) but supposedly the cause is that the system gets more fuel than it expects (during a certain situation) and it hydrolocks because there is too much fuel in the cylinder.
ALSO, there is a section in the ECU that monitors and records when and If the ECU is changed. so SUPPOSEDLY they know when you change it...even if you set it back.

Dont flame me...just sharing what I heard from mazda (while they were working on 2 engines that were blown)

So will Mazda revise their tune to lean things out a bit in the affected areas and issue a recall to reflash our ECU? Did you hear this from a Mazda engineer or a mechanic working at the dealership?

Interesting info but it's hard to believe the engine hydrolocks on fuel. Is this an issue with the calibration, injectors etc etc? Need a little more info regarding this.

Are you saying that the motors are getting to much fuel because of the upgraded cdfp and thats causing people to blow? Last time i checked more people blew with the stock fp than having an upgraded cdfp so that doesnt really hold to much ground imo