Boost Cut Controller, Looks like when the computer sense too much boost it cutting your fuel, from looking at the graph. One of these:

 

what the *****...that feng guy might not be right in the head.

No, I don't have one of those installed. I didn't think it could be boost cut but this is just as plausible as my coil packs, thanks for the heads up...ill start looking.

 

WTH

 

if you are just 13ish psi, not boost cut...
guessing you have a good boost gauge.

Might not be coil packs. If yours aren't craked or anything, might just want to close up the gap a tiny bit.

 

good point, yes I have an APEXi boost gauge that is very accurate.
I haven't inspected all of them to see if they are cracked but the one we took out at the dyno (need to) but I'll get on that tomorrow.

ConSynx, I believe that 13 pounds shouldn't be a boost cut, but are you sure?

 

Those are good numbers man, I need to dyno mine soon. I've been busy fixing little things here and there. I am in Raleigh btw, I might have to meet up with you one of these days.

 

Mine was set to factory PSI, when I first purchase the car. Once I added the twin intakes, I was hitting boost cut. Apparently, the ECU sensed the change in air and adjusted accordingly. Once I intalled the BCC and had the car retuned with my Neo it's 99% eliminated. My Boost is set at 14 psi. But the boost guage will show that I have hit 1.02 bar occassionally at which point it will kick in. Your dyno graph looked like mine when it kicked in and it also sounded like mine too. Just a suggestion. I think you maybe the first with stock twins to hit 350hp on 13 psi. Someone correct me if I am wrong. Again, good job. If I could got that with my twins I would never go single.

 

like Nate said, the 1jz cut should be 15psi.
Some people rock the 2jz map sensor iirc, and get another psi or two. I never did that so i'm not sure about it, or how similar the piezoelectric(spelling error) voltage curves are.
Apexi is worthy of being correct.

You didn't make sense about the coil that you pulled at the dyno.

I am curious like others said if this is SAE corrected, and what dynomometer the runs were on.

Congrats on the numbers. Very good, only thing i've seen like it was the 370 that came from Cams and tuning.

 

Just for clarification for all of us, this is all the info at the bottom of the readout:

Run Conditions: 77.35 degrees F, 30.19 in-Hg, Humidity: 30%, SAE: 0.97. Max Power 340.83, Max Torque: 319.73.

So...after spending two short days on trying to figure out what SAE is, I am apparently hopeless...anyone care to interpret?

 

Word, ill be in touch when spring comes around, going to get on some road tracks and maybe some autocross out thatta way.

 

Here's a small blurb I Found:

Originally, all of the major US auto manufacturers were in or around Detroit Michigan, and the dyno reading taken in Detroit were considered to be the standard. However, as the auto industry spread both across the country and around the globe, the auto manufacturers needed a way to correlate the horsepower/torque data taken at those "non-standard" locations with the data taken at the "standard" location. Therefore, the SAE created J1349 in order to convert (or "correct") the dyno data taken in, for example, California or in Tokyo to be as if the data had been taken at standard conditions in Detroit.

For example, at 85 deg F, 24.71 in-Hg absolute pressure and 0.121 in-Hg vapor pressure, the engine only produces about 81.1% of the SAE rated power so that the required dyno correction factor is 1.233. Therefore, when dyno testing under these conditions, it is necessary to multiply the measured torque and horsepower values by the correction factor of 1.233 to determine the SAE corrected readings. The dyno correction factor takes into account all of the effects of temperature, altitude, atmospheric pressure and humidity to arrive at corrected horsepower and torque values.

The air temperature should ideally be the temperature of the air that is going into your engine.

The absolute pressure is the actual atmospheric pressure, also called station pressure. This is not the barometric pressure or altimeter setting as is typically reported on the local weather report.

The vapor pressure is the partial pressure of the water vapor in the air.

For these calculations, the standard reference conditions are: Air temp 77 deg F (25 deg C), 29.235 Inches- Hg (990 mb) altitude-corrected barometric pressure, 0 ft ( 0 m) altitude, 0% relative humidity.

Source: http://wahiduddin.net/calc/calc_cf.htm

I am sure you already researched this but I am winding down from work and need something to do. The wife is sleeping.

Hypothetically, 2 engines with the same rated Horsepower, would read differently on a given day due to said conditions. 1 engine dyno'd at sea level would read way differently than if it was dyno let's Mt. Everest. That's extreme but you get my drift, SAE correction keeps auto manufactures honest. Unless your Nissan who rated the GTR at 420 but have to be found to make way over 500hp. They must have dyno'd on Mt. Fuji. Good Night.

 

also, SAE - Society of Automotive Engineers.

and 30in-Hg is a slightly above atmospheric pressure. quite the ideal. start...little correction needed.

Perhaps you can pull a compression test. Maybe you are boosting with much higher compression that normal, and the blowout is a lot worse than we think. . .shouldn't be, but it doesn't hurt to check.

I'm really hoping your numbers are just that of a real healthy engine...gives me more hope.

 

i thought i read somewhere that boost cut on 1jz map was 13.5 and 14.7 on 2jz map. i could be wrong though.

 

Thats definatly fuel cut. FYI, boost and fuel cut are not directly related. You can be running stock boost theoretically and still be getting fuel cut.. Fuel cut is caused by the ECU seeing a large airflow value from the MAF which works out to roughly 100% duty cycle on the stock injectors. You were just flowing more air through the MAS than the ECU was programmed to deal with.

Try turning boost down first and see if you have the same issue, If you don't, you know its not the coil. If it does, then change your plugs if you already haven't. Then, if it still doesnt get fixed, check the wiring to all coils and if everything is still ok, then you can start ruling the possibility of a bad coil.

hope this helps

 

Sorry, since I don't know the psi limit for the different sensors, I suggest you search over at Supraforums.
I am pulling lots of fuel, so even at 18psi I don't see a cut, but with my twins I saw a cut barely over 1bar.

Also, 1jz is MAP.