My 3400 build!

[19Cutlass94]

Ill have to find a place for a WBO2 somwhere so I can see that.

Now question; once I know the a/f is there anyway to determine what # injectors Ill need... or can I figure that out now?! Cause Im looking through injectors here and I can get the L82 style injectors at various flow rates.

[19Cutlass94]

yeah I cant use those injectors... the stock 3100 ( L82 ) are 19# @ 43.5... if I went with DOHC injectors.. those are 21# @ 43.5.

[Superdave]

the injectors that came with the engine are 22.5# @ 55PSI, if you drop that down to 43.5 they'll be around 19#.


BTW, the AFR you are seeing on that scanner is the commanded AFR, not the actual. For this application i'd suggest a true wideband setup.. It's an easy install and it'll make tuning a breeze.

[19Cutlass94]

Im going to be using an OTC scan tool to read all the data... Itll read just about everything in the system.

I know for a fact that all Multec 2 injectors ( like the injectors that came with this motor ) flow tooo much and I just cannot use them at all. Really the only bigger injector I can go with that isnt crazy is the DOHC injectors. But Ill be looking into the FPR

[IsaacHayes]

Yeah BaldEagle was running the stock FPR, and just swapped to the 3400 injectors before we were able to tell him to keep the old. Well it ran crappy until he switched back and it was all good.

[ForcedFirebird]

you can go bigger injectors, you wont flood out at cruise. your o2 sensor will shorten your pulse width and correct fueling, as long as you dont go with way bigger injectors.. same thing with the regulator, the computer will compensate for cruising. I have an aeromotive LT-1 AFPR on my 3400.. it required a little bit or grinding on the upper intake / plenum, but it fits ok on my engine other than that. it works out real well too..

i have yet to see any better performance however with adjusting the regulator... maybe im maxing out my injectors.. i donno

That wasn't the case when I went to 24# injectors. The car wouldn't idle to save a life, diveability sucked. I had to turn down the FP to get it to run, then have it raised again during boost. Better off just leaving the stock inj, and raising the FP if you aren't going to tune in the ECM.

[JMo60]

you can go bigger injectors, you wont flood out at cruise. your o2 sensor will shorten your pulse width and correct fueling, as long as you dont go with way bigger injectors.. same thing with the regulator, the computer will compensate for cruising. I have an aeromotive LT-1 AFPR on my 3400.. it required a little bit or grinding on the upper intake / plenum, but it fits ok on my engine other than that. it works out real well too..

i have yet to see any better performance however with adjusting the regulator... maybe im maxing out my injectors.. i donno

[IsaacHayes]

What will you be using to scan and read the data?

[19Cutlass94]

yeah Ill have to see what happens when I start it up, and scan the system to see whats going on. Then once I know that, I can look at what I might need to do.

[ForcedFirebird]

You can use a RRFPR (FMU), it's not ideal, but an alternative for OBD1.5.

[IsaacHayes]

Ah. Hmm so that won't help much to add extra at WOT while not having too much pressure at idle/cruise... darn.

[sharkey]

an adjustable fuel pressure regulator is set by removing the vacume line (so you have static fuel pressure) and adjusting it to whatever you want it. then you hook the vacume line back up and the fuel pressure will drop down. you cannot independently adjust idle and wot.

[19Cutlass94]

Well I think I just need to stick with the Multec 1 injectors. All of them operate at 43.5psi. Mine are 19# and if I go next step up, it would be the DOHC injectors which would be 21#, and are still Multec 1's and operate at 43.5psi.

Its that compared to the Multec 2's which are basically completely different. More psi and larger #

[IsaacHayes]

You'll need to stick with stock injectors so you don't flood at idle/cruise. How does an AFPR work exactly? Is it adjustable for both vacuum and WOT conditions or just one or both are affected by adjustment?

[19Cutlass94]

I dont see why I couldnt use an AFPR if needed. Ive got both the L82 injectors and the Multec 2 LA1 injectors. Ive got an OTC scan tool at home thatll show me the a/f ratio, and a bunch of other stuff, but I believe thats based on what the ECM is reading from the O2. I thought the store here had an AFPR, but I cant seem to find it anymore.