Word! No high end break up any more with C-16
Art

 

Will do, I'll try to fill the tank on 93 and see what happens. Thanks guys.

 

Hmm... I am also always putting in my car 98 octane fuel as instructed from the factory. Could 95octane then help with highend breakup ? (this is Euro 95-98 octane, which is a bit different then US octane)

 

Assuming Euro 98 is the same as NZ 98 octane (which I think it is) then Euro 98 = US 93
There is a good thread explaining this
https://www.rx7club.com/showthread.p...ght=RON+Octane

So if you are currently using Euro 98 and haven't played with your injector maps, (they are OEM maps from Mazda), then your "break up" problem is most likely NOT related to running 98 Octance gas. To run lower Octane gas could create a lean condition and promote detonation under boost.

 

Crusier, the basic rule is run the fuel your car is tuned on. If you are running factory settings, then use the factory fuel recommendations. Within some limits, the computer will adjust for fuel variations.

If you have high RPM breakup the usual suspects are coils, plugs and wires. I had an immediate elimination of that problem, which would manifest itself in 3rd and 4th at around 7,000, when I went to the Twinpower. I later changed out the coils too.

My launch problem however, was not "cured" until I backed off on pushing up the octane too far with race fuel, for a car tuned on 103. You want to run c-16, tune with c-16.

 

That is absolutelly correct. The O2 sensor has NOTHING to do with high RPM break up as the ECU isn't even considering O2 sensor readings at high rpms or boost.

High end break up is usually from running to rich. My M2 Stage 3 ECU sometimes runs a bit too rich at the high end. I added an HKS TwinPower and it seemed to help.

 

Hey John, did you maybe do some AFR readings before and after the HKS TP installation ?
I was wondering what is your complete setup and what AFRs you were getting.

I have same ECU and also have high end breakup, but I dont want to run lean with the HKS TP and risk my engine.

Funny... at 10psi I get no breakup, if I go to 12psi, I get it. Must be the maps on the ECU.

 

Have you done any AFR readings or monitored EGTs at 12 psi? Your maps are probably really rich---like less than <10.4 for those cells.

 

No, not yet. I only have EGT readouts from the tailpipe (on stock IC, old plugs and shitty exhaust back from DP). What temps are expected there aprox. ?

 

The readings immediately post turbo will vary car to car.... Rule of thumb is that you should avoid 900 degree C (~1650 degrees F) post turbo. The fact you are at the tailpipe would make me want to see <750 degress C as a max.

That said, with no breakup and relatively rich injector tuning and conservative timing, I have NEVER seen 1600 degrees F (875 C) post turbo under hard boost (1- 1.3 bar). Most of the time my pre-turbo EGTS are < 900 C. Occasionally under hard boost.....950.

Generally, the richer you are the lower your post turbo EGTs except when the flame front is so rich and/or so late that it is actually still burning the exhaust manifold.

 

I run about 11psi. I have the M2 Stage 3 mods plus a high flow cat. Sorry, no AFRs. I've put 1000 hard miles on the engine since the addition of the HKS ignition and no problems so far... not that that means much