doktor-t

PorKen

"air temp sensor replaced with 5K resistor"

Do you mean the sensor in the airbox? Didn´t you put an resistor instead of the temp2 sensor?

What does the 5k resistor do when replacing the intake air temp sensor?


As far as I understand it would be the best thing to fool the ECU to belive that the engine runs cold (water temp sensor2), is it the same thing with the intake airtemp sensor too?

What about the function when fooling sensors during cold weather?

Currently I use 95 octane fuel in my car and I belive it can handle some more timing with that octane number or should I step up to 98 octane instead just to be on the safe side?


In my daily driven Renault I put a 4,7 k ohm NCT Termistor resistor in series with the temp2 sensor along with an extra curcuit with an toggleswitch just to be able to choose between fooling the ECU or not. This modification was done since I use E85 Ethanol instead of 95 octane gasoline to be able to start the car during cold weather. Basicly the ECU is fooled to belive that the temperature is much colder then it really is and therefor gives the engine some more fuel to ease the starting.




/Tobias

PorKen

The 2K-5K resistor in place of the airbox sensor stops the EZ-F from retarding -3° when the sensor reads over 50°C/122°F (or disconnected, or shorted = octane loop).

doktor-t

Would it be necessary for the EZ-F to retard timing if I run 98 octane fuel? (if intake air temp rise above 50°C)


The modification I´ve done to my Renault, could I do the same to the 928 but use a 20k ohm resistor instead to get some more advanced timing? I like the Idea to be able to switch the advanced timing off if necessary?

PorKen

Back again to the dyno, and even with a exhaust mods (Exhaust system measurements), still no mo'. Sounds good tho'!

I added a few notes to the hi po thread (Tuned EZ-F), including the following.

Fuel pressure (2.5 bar) AFPR

Cool intake manifold, <90°F airbox
Possible bad thermostat, just below upper white line


The fuel pressure was stock, but with a 928 Specialists AFPR. Midrange is identical, but the top end was a bit leaner than I get with a new stock regulator. The air was cold (it was December), and once we isolated the intake manifold so it cooled down, the power went up and up. I think now the thermostat was bad, it ran just below the upper white line, never higher, with a stock 83°C, it runs in the middle. Hot engine, with cool intake = good.


I was trying -4° retard on the cams this time, and I could not get over 295. The 312 was made at 0°. It appears Porsche knew best, cams at zero makes the most HP on an S3?

I'm just chasing my tail now. I think I hit the peak of what the smaller S3 valves can manage, NA. It's all I can do to get back to those numbers.

All I can think of now which I might try is insulating the valley somehow, and making isolators for the intake manifold to the head. A gasket/aluminum sheet sandwhich, maybe. I will be setting the cams to zero!

PorKen

You can see the effect of the cam timing, and top end fuel ratios. (The middle one had the fan disconnected, and no wideband for the test.)

The top run was made at 0°. The lower two, at -4°. The peaks are a few hundred rpm later with the retard.

doktor-t

Removing the bottleneck at both of the plastic airducts would help some ponies.

/Tobias