FMU Tuning???

SxLxAxVxExN

SxLxAxVxExN

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How exactly do you tune the FMU under boost? I read that Fuel pressure under boost shouldn't go over 85 psi? How do I adjust this?
Do I need a fuel pressure gauge?

And Is there any injectors that I could run instead of the stock ones? There's got to be some kind of upgrade injectors.. Or do the s2000 injectors fit in the fuel rail?
I'm a bit confused at this point
banghead.gif
 
I'm assuming this is a stage 1 kit,when I ran the PC3R,I had the FMU air bleed set to increase the fuel to about 85-86 psi.

When I ran the PC3USB,I adjusted it down to about 75,never had a problem.
 
IMO you need a fuel pressure gauge. You need to be able to set the idle pressure and pressure under full boost. You adjust idle pressure with the large screw that goes in the center of the fmu. You adjust the upper end pressure with the air bleed screw on the side of the fmu. If you are running a stage 1 kit with 6-8 pounds of boost the stock injectors will work fine. If you are planning on 10-14 pounds will need to upgrade your injectors. I run the s2000's in mine and they work great with no problems. Still the best upgrade is to run secondary fueling if you are going over 10 pounds.
 
Yes you absolutly need a fuel pres gauge, fuel pres is super important if idle is off low speed tuneing is affected is boosted is off much it will be rich or lean under boost, first you decide what boost your going to run then set boosted pres then the map is adjusted to fine tune. idle pres with stock injectors is normaly 43lbs boosted fuel pres verys with boost pres, more boost needs more fuel up to the limit of stock injectors, some guys run 10-12 boost with the right numbers in the map it will work for the drags or short blasts at 12 lbs boost with 90-95 boost fuel pres and close map numbers your right at the limit of what stock injectors will flow and even then its iffy
 
Once you set everything, you still need the Fuel pressure guage. You should always watch the pressure along with a Air fuel gauge. This will keep you out of troble and always have a backup if one or the other gauge stops working.
 
I forgot to mention that I did a headspacer as well.. plan on starting on 6psi and maybe go up to like 8 or so.
So the s2000 injectors will work with the stock fuel rail? I can just swap them out? The reason I want to go with the bigger injectors is to be safe. Don't wanna blow the motor
sad.gif
 
The S2000's are a drop in replacement. At the boost pressure your decribing you shouldnt need to use S2000's especially with a block spacer.
 
If your only going to run 8 psi boost S2000s are not nessesary and they can be tough to get running nice out of boost. it has ben done but its a pain in the ass. if you have the spacer, you can run 8-10 psi boost with your stock injectors with pump gas, as long as you don't do any land speed attempts, just have the dyno guy build your map for whatever boost you run. you may want to go with water inj for a bit a safety, keeps the intake temps down. if you really want you could go as high as 12+ boost if you run C-16 and water injection if your just going to race it, IMO go with 10 psi boost get a good map done for it put water inj on it and ride it, you should end up with 260-270HP
 
Agree with Dave. I ran into problems at 10 psi. I kept on getting a FI light with the stock injectors. I switched to the S2000's and really like them. I have no low speed issues at all with them. The FI light is gone also. If you stay at 8 psi of boost the stock injectors will be fine. If you decide to go with the s2000's and 10 psi of boost I have a great map I will email you to get you close till the dyno.
 
Sweet.. Could you send me the map? Cause I plan on getting the injectors one of these days.
Where did you buy your injectors from?
Thanks
 
Good luck finding a set. I looked for a used set for about a month finally gave up. MPS sells them, I think they sell for 500.00, to much for me. I'm just going to a secondary setup, sold my pcIIIusb and fmu. If you take the cost of the injectors and the parts I sold I only need 200.00 more dollars for a complete secondary setup.
 
If anyone needs a set of s2000 injectors I ended up with an extra set that i will sell if someone else needs them.
 
I got a set off of ebay for cheap and then sent them to MPS to have them flowed and sonic cleaned.
 
We have tuned a handful of FMU Turbo Busa's with S2000's and never had problem with them running trashy off boost. Only ran a little trashy when they were dump pipes and ran straight C16.
 
Screw it I'll get a set just to be safe, cause i don;t have the money to rebuild or replace the motor, and plan on running about 8 pounds or so. For how much boost is the bosch fuel pump good for? E2000 part number i believe it was or something like that. And I have a vortech fmu
 
Not sure what the part number is off top of my head but i believe it was the e2000 or something like that.. I found it here on the forums.. its a 70 dollar pump.
 
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