Saving a 2008 Mazdaspeed 3

In the log where the hard stumble/cutout occurred, HPFP pressure was between 1700 and 1800 PSI, Knock retard was at .70*, this was on 91 octane and ambient air temp was 43*.

I stopped logging before I turned the engine off. I'll log HPFP on shutdown next time I take the car out and see if I see anything off with the relief valve.

 

Ah. No Ethanol. Could just be bad gas? Do you have access to any E? A gallon or two could help smooth out knock on a full tank.

 

I could get some E85, however the 91 in the tank is regular station fuel, somewhere between E0 and E10 per the fuel company. 91 should be sufficient for a stock boost speed from what I understand. This is also my daily so I am going through at least a tank and change a week.

I do try to get 93 when I can, however there's only one station I am aware of within 50 miles of Tulsa Oklahoma.

 

In 5th at that low an rpm, it's likely a lspi event.

.032 is also too large a gap. Mazda revised stock plug gap to 0.027 with the 2nd gen

 

That actually makes a lot of sense. I should be able to swap my new plugs for a set one range colder and gap accordingly.

Doing some cursory research also points to changing viscosity oil (still running stock 5w30) and ensuring carbon buildup is minimized. Other knock/lspi prevention measures such as moving to a FMIC and fuel additives seem warranted as well to prevent catastrophic engine failure.

 

Wut. How does a Fmic vs tmic help prevent engine failure? No need for fuel additives, just make sure injectors and intake valves are cleaned on a maintenance cycle.

Also 5w30 oil is fine for stock engines, and plenty of built ones depending on ring gap. 5w40 was recommended to help stop smoking k04, which certainly an issue on the first gen turbos on my gen 2 I'm 118k km with 5w30 no smoke. Oil type is going to play a bigger role than viscosity (yes that's still important not saying it's not)

Checkout this thread for recommendations on oil types based on used oil analysis for our engines.
https://www.mazdaspeeds.org/index.php?threads/best-engine-oil-all-mod-levels.7931/

 

You don't need colder plugs you likely don't need new plugs just tighten the gap down.

I had the same issue and it was one plug that had mysteriously had the gap open way up I tightened it checked the other three and have been fine for 30k miles

 

The thought behind a FMIC vs TMIC is due to Intake air temps. The cooler I can keep the boosted air entering the engine, the less propensity to detonation there is. With a byproduct of slightly better efficiency and power too.

I recently cleaned the valves when I had the stock K04 turbo rebuilt. Cleaning them on a maintenance schedule is definitely on the board. An added catch can should help keep buildup down somewhat as well. Currently running Mobil 1 Full Synth, however I think a change will be in order shortly after researching LSPI and the link listed above.

Regarding Fuel, I put no lower than 91 octane in, and when I can find 93, I fill up with that. Unfortunately I have only found one station within 50 miles of my location that even has 93... I had hoped that 91 would have been sufficient for the engine, provided tthe rest of the engine was up to par.

On the plugs. I put plugs in when I got the car about 2 years ago and haven't replaced them yet. With all the issues I have worked through, its not inconceivable that they may need to be replaced again.

 

Improper flow balance from the shitty stock intake manifold and exhaust manifold Will play a bigger role in engine life than Fmic vs tmic (especially if tmic is upgraded). Bad injectors that need cleaning is also part of the problem on these cars (any DI engine really).

91 is perfectly fine as it's what the stock tune is for, even if you get tuned as long as it's for 91 then all good.

2year old plugs sure could need replacing, could just need a re gap on them. If you're stock/stockish stick with stock heat range plugs.

 

Can't hurt to try new stock heat rage, smaller gapped plugs and see what happens.

I hadn't found anything indicating what the stock tune was based around for fuel octane and mainly assumed that it would adjust if needed.

Since the engine is a replacement from what I can tell, I bet the injectors are probably original and never been removed and cleaned. If I continue to have issues, getting a spare set and cleaning them may be in order. Kinda sucks that I just put the Corksport seals on and as far as I can tell, they are a bit of a 1 time use seal.

 

you mean the thing on the fuel door /cap that says 91? or in the manual? that would be what it is based on.

def nothing wrong with trying fresh plugs

 

Or go the free route and just gap the plugs

 

I checked and mine only says "Premium Fuel Only" with no octane listed. I'll have to look, but I may not have gotten the manual when we purchased the car. At least now I know 91 is the original target fuel octane.

Pulled the plugs and they looked pretty decent actually. while they are chronologically about 2 years old, at least half of thatt time the car was not driven due to ongoing repairs. I'd say less than 6000 miles on them. I did find that the gap that measured greater than .035 and totally could be a contributing factor to the stumbling issues. I regapped them down to about .026-.025 and reinstalled. Should be able to tell on tomorrow's commute if it helps.

 

"91–94 (premium)" https://www.fueleconomy.gov/feg/oct...S., unleaded gasoline,(more about that below). 91 min...
https://en.wikipedia.org/wiki/List_of_U.S._states_by_standard_octane_ratings again 91 min listed...so as you said it says right in the manual what fuel type to use...

Plugs look pretty good, id hope so after only 6k. hopefully the re gap helps

 

So far, the re-gapped plugs seem to have alleviated my cruise/light throttle stumble. Fixing a loose boost hose clamp helps as well.

Also had a bit of a realization after further research and looking into the logs. I believe the hard "stumble" is actually boost cut (in the order of about 16.2 psi in the latest log). I believe this is due to a fully functioning K04 along with the catless downpipe resulting in overboosting, especially in colder temperatures. I have already been planning to get the car tuned, just waiting for funds at the moment. Aside from maintenance, the tune is next on the list.

 

Catless do with no tune? 100% found your problem dude.

 

^ that'll do it. Glad re gapping plugs helped

 

Had a good day at the local junkyard this weekend. 25% off and t here was a seemingly unmolested CX-7 in the yard. Made off with the nearly entire head (minus HPFP, someone had pulled that already), timing cover and oil pan for just about $100! This included cams, injectors, exhaust manifold and a bunch of bits and bobs still attached to the head. I left the turbo and transfer case as I ran out of time. I also recall the CX7 K04 not being as desirable and I didn't know if the T-case was of value to any of the Speed6 guys. This will make good spare parts for if/when the stock 2.3 goes ZZB and I end up 2.5 swapping the car.


I am continuing to work on the car, but it is currently mainly tune related on a separate thread in the tuning section. I still have other work to do on the car, but tuning is needed from the mods and I need to finish up another car before I can tear into the loose steering mount issue. One thing at a time.

 

Dam that's a great parts score on Injectors alone

 

The turbo is smaller and there were two different transfer cases used in the cx7 one swaps directly into the six the other requires cannibalizing parts from a speed six transfer case

Edit and technically they aren't transfer cases they are power take offs whatever the hell the difference is