when do i need to upgrade my fuel system ?

[dorifuto.boi]

right now i can get an afr of 11:1 during WOT. so how do i tell when i need fuel system upgrades ? when my afr starts to increase during WOT at high rpm ?

is it correct that i need a tune after i upgrade the fuel pump and injectors ? my reasonings for this is as follows:

fuel pump: if i upgrade the fuel pump, then for the same voltage applied to the fuel pump, the upgraded fuel pump will flow more therefore providing a higher pressure in my returnless fuel rail therefore increasing fuel output at the injectors. therefore a tune is needed to decrease the pulse width on the injectors

injectors: if i upgrade the injectors, then for the same pulse width applied to the upgraded injectors by the ECU, more fuel is outputed therefore a tune is needed to decrease the pulse width on the injectors.

is this all correct ?

thanks,
d

[trd4life]

When you run a walbro on a returnless camry/solara, its overruns the OEM fuel pressure regulator and causes the fuel pressure at the rail to increase. So your fuel trims get thrown off because each times the injector fires, there is more fuel going into the engine so you a/f richens up.

When you upgrade injectors same thing happens, each time the injector fires there is more fuel going into the engine.


The SAFC or piggybacks are what increase and decrease pulsewidth. So when you do the above mods you use the SAFC to lower injector pulsewidth to TUNE the car. Or you could add a return style fuel system and adjustable fuel pressure regualtor which you could use to maintain the OEM fuel pressure after installing the walbro or you could use it to lower the idle fuel pressure to compensate for the larger injectors.


list all your mods for me.

[dorifuto.boi]

-obx short ram which im about to extend into fender to suck up colder air.
-im about to install 1 level colder denso spark plugs.
-trd supercharger. 3psi@redline
-im about to get obx headers 2.5"
-megan racing cat back. is it 2.5"

-will get aem fic soon
-will get meth injection when i get the aem fic

blown knock sensor. im going to replace the knock sensor in a few weeks. after i replace the knock sensor, im going to make a det can to see if im actually knocking (that caused the knock sensor to blow). if im knocking, im going to lay off the gas pedal until i get the fic and meth injection so i can tune.

if i dont hear detonation, then im going to check the ignition timing to see if its being retarded. if it is, then its due to noise so i'll have to decide if i should relocate, etc so they dont pick up as much noise.

if theres no detonation AND the ecu isn't pulling timing, then i have no idea why the hell the knock sensors blew.

**right now, im looking at fuel upgrade options because people keep telling me that i am running lean and i need to upgrade my fuel system. but i dont see how my fuel system can't support my car because i can get 11:1 afr on WOT even at redline. im pretty sure my fuel system is OK but its my tune thats causing me to run "lean" at high load before it goes into open loop.

**the only weak link i can see in my fuel system right now is the distribution of the two fuel rails causing some cylinders to go lean. so im going to make a custom fuel line from the filter to the rails. but like i said, im still looking at other fuel upgrades cause i want to learn about them and how they can help my car. mainly how i can tell when i actually need those upgrades when i up boost

sorry for such a long post. hope it wasnt too confusing.

thanks,
d

[trd4life]

yes the fuel lines going from the fuel filter to the two fuel rails need to be upgraded, there is a large restricition in the OEM fuel lines. I acutally sell the upgrade kit you are referring to. You may also need to order one of my upgraded GM knock sensor kits. the OEM sensors will sometime blow out just from the whine of the s/c but i would do the fuel lines first.