If you have the JWT ECU programmed for 300zx Injectors, and you have 300zx Injectors - do you need a FPR for idle pressure and an FMU for tuning?

Or only fine-tuning with an AFC?

Thanks,
IanS

 

No you do not need anything you rip off all existing FP risers and regulators, just plug your ECU and install your new 300Z injectors and drive off. JW, has charged enough money to run the injectors by itself and you will not need no JS you will be just fine.

 

ummm...yes you will need an FPR, if you have a high flow fuel pump. not sure if you need one if you dont have a HF-FP.

here is my story...

when we installed the SC on my car...JWT hadnt sent the SC program eprom (little chip) to me yet so we set it up with the stock injectors, stock ecu, and FMU.

so 2 days later when the chip came in, i stuck it in my JWT ECU, installed the 370cc injectors, removed teh FMU, installed the JWT ECU. start it up....ROUGH idle, car is BARELY running. i get out to look, reeks of gas...i look out back...gas shooting out of the tailpipe. turn the car off.

i troubleshot everything. pulled all the injectors back out to check the o-rings...they are all good. check all the fuel lines...they are good. check the ECU harness is plugged in all the way. so it had to be something i just put on the car i.e. injectors or ECU. the injectors checked out so i figured it had to be the ECU in some way. either they misprogrammed it or it was just muffed up in some way.

did some research...come to find that with the walbro pump and 370cc's it flows too much gas for the ECU to start adjusting. FIX: adjustable FPR to bring fuel pressure down to levels that the ECU can adjust and tune itself with out the use of the FMU. i believe some other members have had the same issue with this setup and the FPR fixed the situation. i ordered the AEM FPR (SARD no longer available) and should have it up and running by the middle of next week.

since then i have just been running the (stock) setup...stock injectors, FMU, stock ecu. so i will have to pull the manifold AGAIN to put the 370s back in and get it all working.

so maybe that answers some questions.

--Paul

 

Hmmm....sounds like opinions differ.

JAY25 - you don't need anything.
Requin6 - You need at least an FPR.

Anyone else wanna break the tie?

 

yes you will need an adjustable FPR..the walbro pumps more fuel than OEM..JWT programs(as well as most injector upgrade programs) are set to run on OEM fuel pressure....the Walbro raised pressure ~3-5psi so we needed an adjustable FPR to LOWER pressure back down to stock where the ECU is set to operate...we did this on Max O/Ds 3rd gen with JWT 370cc program(before Z32 program was added).

 

You need a FPR. The stock one will work, but unless you go stand-alone (and maybe even then) you'll always need a FPR.

 

Good thing you have the Cartech. You should be able to adjust the base/wot pressure Ian. Just don't put a vacuum line to the boost referenced fuel pressure side I guess

 

Unfortunately the Cartech fmu doesn't allow for adjusting the base fuel pressure.

I'm glad this post came up, I've been running the higher fuel pressure since installing the Walbro pump. With the 240 cc/min injectors it's not really an issue. I didn't think about how the 370's will be much more sensitive to fuel pressure, so I learned something good here.

 

I thought that was the advantage of using the Cartech? Maybe it was the Vortech?? I dunno. I know Ian had one that featured adj. base/wot pressures.

 

The Vortech Super-fmu allows for base pressure adjustment, but I'm pretty sure the Cartech doesn't.

 

The Cartech FMU doesn't adjust anything at idle. It only works under boost.

Which is why I'm asking this - it's sounding like if i get the JWT ECU with the 300zx injector programming, the injectors, and a AEM FPR - then I don't need the Cartech unit at all.

Correct?

IanS

 

correct

 

That is my understanding. Of course, once you get up above the capacity of the Maxima maf (350 hp according to JWT), then you can start playing around with a boost referenced fuel pressure again.

Or you can go to the Z-32 maf, which will get you up to 420 hp.

 

last time I talked to one of the Jim Wolf tech/reps and mentioned any usage of an FMU on with the system...he nearly took my head off they seriously hate that thing with a passion which is understandable form their standpoint.

 

Yeah, I got that impression from talking to them, too. But once you exceed the flow capacity of the Z-32 maf, what are you supposed to do? Will the Z-32 maf handle huge amounts of horsepower along with larger injectors?

 

from what I read on the 240(SR20DET) and Z31 boards and many of the other boards, many of the high HP setups(500+ hp range) are running the Z MAF into the mid 500whps(I think Danny88Z on Z31 is making 560ish on the JWT/Z MAF setup, not sure on his injectors though) I think when you start making GOBS and GOBS of power its standalone w/ MAP sensor time by then

 

Chances are if you can max out the Z32 MAF, the engine probably won't be stock internally anyway . I've seen mid 500's from Z32's on the stock MAF.

 

A MAP sensor is the way to go IMO, but is standalone the only possibility? Can JWT convert from MAF->MAP?

Don't the Supra guys have the HKS V or something that allows them to toss the MAF and go with a MAP?

 

standalone does seem like the only possibility at that point, but I dunno for sure and I'm not sure uf JWT can convert, would be interesting to know though.

those Supras are probably using the HKS VPC, converts MAF-->MAP...it is a serious ungodly ***** to tune, it drove my friend plain crazy!!! pretty sure thats why it was discontinued on the US market. nice unit though, very complicated if you're not experienced though!

 

I worked on a SCed maxima with no FPR no FMU, thats why I posted no FMU or FPR, I never checked the fuel tank or listened for the fuel pump.

 

True...

Some stock fuel systems can support up to 6psi of boost on stock fuel pressure. The limit being the stock injector flow rate at stock fuel pressure and max duty cycle.