Begi 2025 FMU tuning
 

i jus picked up this beauty on ebay

http://cgi.ebay.com/ebaymotors/ws/eB...2335192&rd=1,1

don't think he gave me the check valve though. other then the check valve does it just hook up like a vortech fmu ?

i read up on it on the begi site, but im still kind fuzzy on exactly what the check valve does. will this fmu be able to run without the check valve ? or should i just go ahead and order one from begi for 7 bucks ?

also...should i just follow other Scott's guide on figuring out how much fuel pressure i have then doing the 5 psi/per lbs of boost thign ?

Scott

Yes

Check your local autoparts store. Should be a couple of bucks.

No. You need to tune it with a wb or on a dyno. BUT what I found out with mine is that the only usefull adjustment was the overall pressure (the center screw adjustment). My needle valve (the adjusment that determines the rise) is as open as it gets without risking the knob falling out.

Check valves can be bought in the HELP! section of autoparts stores.

To determine your fuel pressure we gotta factor in your injector size and boost you are running and we can put you in the ballpark. But you won't ever be dead on untill you do some datalogging with a wideband.

alright ! everything i needed to know. thanks ben and scott.

well as i posted before about my turbo lag and fuel issues, im not running a vortech with my base greddy kit... only addition was a starion intercooler.

so im running stock 1.6L injectors @5psi /w intercooler.

in OEM from the Greddy kit runs a 12:1 ratio. You should shoot for 95-100psi or so, however you probably still have the stock FP so shoot for just under the max output of the pump.

No problem shooting for the max pump output on rise with the OEM. Lucky if you get 80psi.

My OE pump only got a spike of about 70psi and dropped off to 60psi!

i was going over your fmu install and the one posted on the begi site scott... and it seems to contradict ? or am i reading it wrong ?

"The most difficult aspect of installation is getting the fuel lines onto the correct fittings. Older model regulators, made from castings, had labels of “in/out” on the barb bosses. “In” is for the fuel line from the stock regulator. “Out” is the return line heading straight back to the fuel tank. The “in” and “out” of the new regulators are similarly designated. "

this is whats listed on the begi site...from what i undertsand its saying to place the fmu between the line that returns to the fuel tank...

and you says to take the line in the front of the fuel rail plug it in the "in" barb and the fuel return on the out barb....

whats the dealio ? an i just dumb ?

"In" is for the fuel line from the stock regulator" is the same thing. You are cutting the return line going back to tank and placing the FMU between the stock fuel regulator and tank. The port labled "IN" is where you put the line coming off the stock fuel regulator. You do not touch the line coming from the fuel pump to the rail except for tapping that line for a fuel pressure gauge.

yeah, re-read my instruction carefully. I should change the wording.

follow this example of how the fuel should flow:

FEED HARDLINE -> PRESSURE GAUGE -> FRONT OF FUEL RAIL -> OEM FPR -> IN PORT OF FMU -> OUT PORT OF FMU -> RETURN HARDLINE

basically pull the line the attaches from the FPR off the hard line and connect that end into the fmu. connect the otherside of the FMU back into the hardline you just pulled the other line off. the feed line is never touched.

alright, thanks guys. i think i got it figured out. now i just need to figure out how to tune this puppy....

ok, scott. i made up a little fuel pressure dealio.

how can i figure out how to tune this puppy now ?

at idle. my fuel pressure is 40 psi.... when i mess with the screw on the side of the fmu it turns up the pressure by about 15 psi. and the adjustment screw on the top of the fmu clockwise turns up pressure and counterclockwise turns it down...

im running 6 psi right now on stock injectors and stock fuel pump...

First, jump GND and F/P in the diag box.

turn the car to ON, you;ll hear the pump.

clamp down on the return line and see what the max the pump will go to.

Remove the jumper, start the car.

idle should be 35psi. Removing the vacuum line to the OEM FPR should shoot it up. Turn the top screw to tune for 50-55psi when you remove the vacuum line. (make sure to kink the line so you don't kill the engine)

Now for the fun part....you must have about 4' a fuel line to your gauge. Stick the gauge under your wiper blade and go for a drive. See what your fuel pressure reaches when you boost. You'll turn the small bleeder valve to turn the max fuel pressure.

tune for whatever reading you got from the first reading, probably 70-80psi.

ok scott, i just went outside and did the jumper thing. car read about 82 psi. when i clamped the return hose down.... but it was already reading 80 psi without me clamping the hose yet....

ok after i figure that i can reach about 80 psi on the stock pump. i have to try and make the pump do 80 psi while under boost right ?

So, when i start up my car and it idles at around 50psi, i should turn it down to the stock 35psi, then remove the vaccum line to the stock fpr, and kink it.

idle pressure will go up, but then i adjust it with the top screw on the begi pfr and turn the pressure to around 50-55psi ? after i get that to read 55 psi, i plug the vaccum line back in, should the pressure go back down to stock idle ?

after i get that figured out, i drive around with gauge in window and adjust the pressure with the little screw valve on the side until i get the pressure under boost to be around 80 psi ?

yes, i think you got it. full boost and WOT it should hit 80psi. 80psi without clamping meant the top screw was turned in way too far.

horay ! i think i got it. under full load boost and wot, it jumps to 74psi, just need fine tune the knob a little more then ill be set.

ok scott.... it seems to be working.. but im getting some strange problems

sometimes, kind of randomly while im stopped at a light when i try to drive off again, the whole car kind of bogs down and is on the verge of stalling even when WOT.... could the injectors be locking up or something ? i just upgraded to 265cc yellow top injectors too...my car never had any of these problems until i upgrades to a begi fmu. could it be an issue with the way im setting up the rising rate knob ?

any ideas or help would b appreciated.

Scott

does it just feel like its hestitating as it goes into boost?

sometimes, while half throttle it will stutter while trying to develop boost.