Mazdaspeed3 (08) built bottom end

[Hunts_ms3]

Car starts up then dies after the rpms just drop and only way you can catch them is putting the gas in all the way anything less and nothing happens, anyone have any solutions, everything on the motor has been replaced everything is basically brand new ,wiring, fuses, relays everything


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[Varomnia]

What mods are you toting? And other than a built bottom end, was any mods added to the mix?

Assuming you upgraded to a different intake during this conversion, try unplugging the MAF sensor and see if it'll run without too much issue. If that's the case, and you haven't gotten the new intake tuned, get a tune. We got lots of good e-tuners here who can tune on either Accessport or Versatuner.

[Hunts_ms3]

Running big turbo, st intake mani, 3.5” intake, fullrace manifold, 3” DP , 3.5 bar map sensor, 3Port BC , DW300c In tank pump, HPFP internals,fmic , corksport big Throttle body.Car will start up and can sometimes idle for little with pedal 3/4 in but if you lift of it dies


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[Varomnia]

Originally Posted by Hunts_ms3 Running big turbo, st intake mani, 3.5” intake, fullrace manifold, 3” DP , 3.5 bar map sensor, 3Port BC , DW300c In tank pump, HPFP internals,fmic , corksport big Throttle body.Car will start up and can sometimes idle for little with pedal 3/4 in but if you lift of it dies Sent from my iPhone using Tapatalk

Were any of those mods you just listed put on before or after you noticed this issue?

[Hunts_ms3]

All on , Car been in out for while trying to solve a fuel pressure issue which took roughly 4 months. Now that the pressure is good the car just won’t stay alive


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It’s been a battle to get this car running


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[Jeff23spl]

There is another thread beside yours with similar problems and good tips.
You may take a look

[Carskick]

Is the MAF calibration correct for your mods?

As Varomnia mentioned, the tune needs to know how big the intake is.

[Hunts_ms3]

Engine hasn’t even been broken in yet, every time the cars starts, it’s starts up like cold start for about 6 seconds then dies.


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[Carskick]

Originally Posted by Hunts_ms3 Engine hasn’t even been broken in yet, every time the cars starts, it’s starts up like cold start for about 6 seconds then dies. Sent from my iPhone using Tapatalk

If that MAF tune is not correct for your intake, it likely won't run at all or will just die after starting. Has your computer been tuned for your mods? Whether or not the engine is broken in doesn't matter. in fact, if you're not tuned, you can't break in your engine, cause it won't run.

[Hunts_ms3]

Ok what do you suggest I do


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[Jeff23spl]

Good point, you can't run a stock tune with different sensors range.

Usually when you get extanded range sensors is because you understand the need and how it works. The 0-5v signal remain 0-5 but 5v means a lot more than before and the ecu need to know it.

The MAF would peg on positive LTFT/STFT but cannot compensate for a huge change like that. when it read 100g/s it pass about 175g/s....It probably get even worst at iddle speed...

Similar for the map

You either need a special maps for your mods that will need to be made again after break-in (Etuner usually help for this)
Or you can switch back to oem map and maf hosing for the break in period but make sure to stay low boost to avoid pegging the sensors.

[Carskick]

You need to get a tune for your size intake, preferably for your particular one, or return to a stock size. Diameter is the primary variable, but there are others.

[Hunts_ms3]

MAF is all good not the problem, thinking of pulling the motor and again


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[Hunts_ms3]

By passed the whole maf and still having same problems


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[SSinstaller]

Your new MAF housing means that for a given voltage you're actually flowing almost 62% more air. Without a proper tune the ecm will not be injecting enough fuel for it to stay running.

Getting the idle calibration close enough to run isnt very hard at all. Multiply the original maf calibration by 1.619, and you'll be close enough for it to idle. Then you just do a normal maf calibation to fine tune it.

[Jeff23spl]

Originally Posted by SSinstaller Your new MAF housing means that for a given voltage you're actually flowing almost 62% more air. Without a proper tune the ecm will not be injecting enough fuel for it to stay running. Getting the idle calibration close enough to run isnt very hard at all. Multiply the original maf calibration by 1.619, and you'll be close enough for it to idle. Then you just do a normal maf calibation to fine tune it.

This + map scalar, but as long as he possess ATR or Versatune...

Originally Posted by Hunts_ms3 By passed the whole maf and still having same problems Sent from my iPhone using Tapatalk

What do you mean by bypassing the maf ???

You MAF and MAP need to be addressed together. Even if you find a way to keep the car idling, it won't be safe to drive it this way.

[Hunts_ms3]

Pulled motor back out , reassembling it. The that built motor was stupid so hopefully when valve cover comes off we can see the issue right away.


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