Their is a bit of a trick for the Idle, setting up the cell value correctly in the 500-1000rpm from 0 to -5.1Hg and then blend to -28.5Hg. If the cell values are out of range, the O2 sencers can not do their job and the ECU will be constantly changing to try and maintain Idle and 14.7 A/R. But it can't so you get an eratict Idle. Some people have said that the SS BOX does not control Fuel in closed loop..... Cell Value must be correct in Vac and well as Boost. Any tuner that just tunes a car for WOT is not a Tuner, their just a guy what dyno to take your money. A real Tuner, will tune a car in full Vac to full Boost and from O rpm to Redline, Idle, Mid Range, and WOT.

I''m using the stock Fuel Pump, It's a good idea to to upgrade and I'm in the process of doing so. I'm for sure maxing out the Stock Pump.

 

When you swap out the pump to a higher flowing Walbro , make sure you do the drilling mod's to the pump recommended by Phunk or you will see fuel pressure's in the 80' s at idle and difficulty with driving in traffic because the ECU/inj won't like controlling at this high a fuel press. That's what I experienced till I went with a RFS..

 

thank you everyone for your replies.

after doing a bit more research, i have come to the conclusion that i will be fine running the 3.12 pulley with my current mods and a retune. i think i'll hold off on upgrading though.

nexx made a good point about piece of mind. i definitely dont want to do a half-arsed job upgrading my car and i will upgrade the injectors and fuel pump as well. its better to be safe than sorry in the end!

what size/brand injector and fuel pump would you recommend. is this a hard upgrade to do yourself?

 

I wouls still say to upgrade the SS box....

 

get Deastchwerks injectors and upgrade to UTEC if possible.

 

what size injectors?

 

Go with 550cc at least, they will give you plenty of room o work with 440cc are still alittle to small.

 

jpc350z. "What is IDC?" Injector Duty Cycle

 

can you tell me what values [ numbers ] you put in in the idle rpm cells ? 10 being no change to the ECU and going down from there for bigger injectors . I had tried any where from 9.8 to 8.4 at the idle rpm range with no luck at getting a stable idle . I also had a OBD to check both long and short term fuel trims .

 

I have 650cc

 

My 440 injectors max out at 6k rpm with 3.12 pulley set up (SSV HFC Headers and Exhaust). Can I upgrade to 650cc and just use the stock fuel rail and Walbro only? Also, can the utec scale the 650cc good?

 

Correct. Seems like 80% max is optimum..

 

We have close to the same set up then. Utech and Walbro May 8th

 

How are you 440cc injectors maxing with the 3.12 pulley? I never had an issue with the 3.12 running stock injectors and I run my car pretty rich.

 

Upgrading your injectors and fp is definitely a good idea if going with the 3.12. No, it's not necessary but like Nexx said . . . piece of mind. I'm running 550cc DW's and a Walbro fp.

 

i snapped my s/c belt so i'm gonna take it to the shop and have the 3.12 pulley put on as well as a few other things. do you think i'll be alright with 440 injectors and new fp with the SS box? should i go with 550 injectors? will the SS box be able to scale the new injectors?

 

if you have the full kit, the stock injectors are probably fine

 

Do this and go with a 2.87 pulley and maybe upgrade to a utec. I should of listened to Jason and went with the 2.87 as the 3.12 is ho hum.

 

it's never too late.

 

I'm putting it on over the winter Just waiting till it warms up for the tune.