Mazderati

Some insight to how the timing actually takes part, however, is nice to know.

IHEnter

i know the mixture gets richer under hard acceleration to prevent detonation at high rpms, but does anyone know where (throttle opening) the stock ecu increases fuel and what the a/f ratio goes to? what does the a/f ratio goto stock under full throttle and what is the leanest it can go under full throttle and still be safe?

Fd3BOOST

I can check those for you on my keypad.

Under part throttle and WOT.

But as far as a specific A/F that is safe.

Isnt that gonna vary from car to car considering the changing variables?

j9fd3s

what the fd does, is once you leave the idle map (1200-1500) it goes into closed loop and looks at the 02 sensor, so its running 14.7, then at 1psi or 3200rpms witchever comes first, it goes to 10:1. if you had a better computer you could run it leaner a little longer, but the fd ecu is slow compared to the turbos over 3200, so they tune it rich.



the fc is similar but its switchover is 3800, it doesnt quite go full rich either (i think), because its got an afm and can keep up with the turbo



mike

dynamite kid

Lets say i was running a afr of 11.5 with ign leading at 12 degrees..Then i increase timing to up around 14-15 degrees.Will this cause a lower afr and ill have to retune the fuel map or will the afr stay at 11.5?

Srce

Whoa, a lot of stuff here.



Here are my questions:



What are all of the things involved in a COMPLETE MAP for lets say (not to complicate things) a stock 13B-REW.



From what I've read here, it's timing, fuel, and air. But, what's retardation, and knock, and detonation, and how do you avoid the things that you don't want (i.e. knock and detonation)?



Obviously they are bad as they cause death to an engine, but how do we avoid them when tuning?



Also,what's the point of logging info into the datalogit or whatever you're using?



How do we start tuning an engine to take more mods after the "3 mod rule" on an FD?



It is my understanding, that when tuning a stock engine to right away going to 500HP on a T78 for example, one must tune for EVERY RPM increment as when accelerating to WOT till redline, the engine demands more fuel? Or does it? Does it demand just more fuel, or more fuel, air, timing etc?



We always say that the ratio between fuel and air is always the number of fuel, per one air (i.e. 11:1, 10:1), I don't think I understand why that is? Why only one air?



It's not like the engine is sucking in only one (sorry, but I don't know what the measurment of air is in, is it punds, kilo's etc?) air per stroke, or is it?



Thanks for reading!!!

j9fd3s

ok step by step, its one air because other wise you have fractions, ie 13air to 27fuel. notice its a ratio of the mixture, not the quantity.



basically the map is the timing of the spark and the timing and quanitity of the fuel.



the spark needs to be delivered at the right time, and is influenced by rpms, (it takes a set amount of time to burn fuel, and rpms change, so at high rpm you have to spark earlier, to get the flame to burn at the right spot).



the fuel needs to be injected at the right time and quantity also.

the timing is basically how long it takes for the fuel to get into the engine, its realted to how far away the injector is from the port, and is affected by rpms just like the ignition.



the fuel quantity is influenced by a lot. the port design, the cumbustion chamber design, the size of the engine, the air temp, the coolant temp etc etc



so to address the tuning fd after 3 mods question:

the further you get from stock the more you need to change in the map. so for 3 mods you may only have to add a bit of fuel, and maybe retard the timing a couple degrees right at wot, but a street port needs more fuel at idle, and slightly different timing etc etc



mike

Srce

ok step by step, its one air because other wise you have fractions, ie 13air to 27fuel. notice its a ratio of the mixture, not the quantity.



basically the map is the timing of the spark and the timing and quanitity of the fuel.



the spark needs to be delivered at the right time, and is influenced by rpms, (it takes a set amount of time to burn fuel, and rpms change, so at high rpm you have to spark earlier, to get the flame to burn at the right spot).



the fuel needs to be injected at the right time and quantity also.

the timing is basically how long it takes for the fuel to get into the engine, its realted to how far away the injector is from the port, and is affected by rpms just like the ignition.



the fuel quantity is influenced by a lot. the port design, the cumbustion chamber design, the size of the engine, the air temp, the coolant temp etc etc



so to address the tuning fd after 3 mods question:

the further you get from stock the more you need to change in the map. so for 3 mods you may only have to add a bit of fuel, and maybe retard the timing a couple degrees right at wot, but a street port needs more fuel at idle, and slightly different timing etc etc



mike [/quote]

Ah, so that's what timing is. So is retardation speeding the timing up, or slowing it down? Speeding it up right?

jspecracer7

slowing down

Srce

Gotcha!!!