Got smart, installed my fmu today

[John_D.]

Wow, I should have thought of this earlier...

So yesterday at lunch I mocked it up. The only reason I didn't try to put it on before, is the lines for it were cut, and the quick-connect ends were missing.

So today I ran down to Advance auto parts and asked if they have the ends, and guess what, they do! I figured I'd have to go somewhere special and have some lines made. So $10 each for 2 fittings, and off I go....

Get home and found some clamps and some vac hose. Hooked everything up. Applied 10 psi of test pressure (using the air compressor) to the fmu and watched the fuel pressure go from 40psi to 80psi! :D

So everything was hooked up right and working. Headed off down the road, hit it, and the pressure only went up to 60psi.

Then I cranked up the dial on the boost-a-pump to 35% to keep the fuel volume up, hit it again, and it held nearly 80psi for the duration, on a quick pull.

Autotap shows I was running .92v on the o2's until 4800 rpms on 60psi. Now it holds .92v until 5300 rpms on 80psi. Still drops off fast after that though.

Before the fmu, the o2's were all over the place while I was boosting.

So now I need to monitor the pulsewidths too, and see if the injectors are maxed out, or if the pcm is just not holding them open long enough, or if I need to turn the bap up to max (50%).

No spark knock on the shifts now either. [img]smile.gif[/img]

[98GREENGLOW]

Kool....PLEASE keep posting your auto tap results so I can copy you when it's perfect. Right now mine goes up to 80 on 7 pounds of boost.

How much boost are you running and what would be the optimum v reading?

[98GREENGLOW]

Im going back to the track tomorrow on my 15 inch rims.

Im having a hard time catching traction with them and have my tire psi at 17 and I still burn rubber off the line and through second gear....How much lower can my psi go????

So Im taking it that for 9-10 psi I want about 80 psi fuel pressure??????

I hope thats what your saying in your post because Im gonna tune it to that tomorrow, with my fmu bleeder.

Im thinking you were right about what you told me about my fuel being the reason my car trapped so low last time. My fuel was closer to 100 psi. I thought the added fuel would be needed at the higher boost levels, but your auto tap has shown the truth.

Respond or send me mail on what you thank the optimum pressure would be.....THANKS

[Arctc Wolf]

remember that as u increase fuel pressure, u will lose some flow from the fuel pump, since it has 2 pump harder to make that psi. the boost-a-pump is a good thing to get more flow from the pump with a higher psi. check ur pulsewidth, and maybe up the boost-a-pump some more and see how it looks. good job btw.

[John_D.]

Originally posted by 98GREENGLOW:
Im having a hard time catching traction with them and have my tire psi at 17 and I still burn rubber off the line and through second gear....How much lower can my psi go????

So Im taking it that for 9-10 psi I want about 80 psi fuel pressure??????

Respond or send me mail on what you think the optimum pressure would be.....THANKS

I'm thinking somewhere between 70 and 80. It just depends. Injector size, air flow, etc. It's hard to say without being able to monitor the o2's. I'm running bigger injectors on mine.

As far as tire psi, I'm not convinced that lowering pressure on a street tire helps. I know it helps on a drag radial or slick, but I think it hurts traction on a street tire because the contact patch deforms and you put less rubber down. I ran 32psi in my street tires on 18's and pulled a 2.04 60' time last year on the spray. I did pull a 1.88 60' on ET Streets at 19psi, but that was ET Streets.

I found out that my fmu is not gradually increasing the fuel pressure. As soon as it detects any boost, the fuel pressure jumps all the way up to 80psi. I don't know if the fmu needs work, or if I did something wrong, or if this type of fmu just gives it all to you at once.

[John_D.]

Originally posted by 98GREENGLOW:
Im having a hard time catching traction

Is it true that you don't have lsd? I imagine it would be very difficult to get traction!! Especially with a blower! [img]smile.gif[/img]

[John_D.]

Originally posted by Arctc Wolf:
remember that as u increase fuel pressure, u will lose some flow from the fuel pump, since it has 2 pump harder to make that psi. the boost-a-pump is a good thing to get more flow from the pump with a higher psi. check ur pulsewidth, and maybe up the boost-a-pump some more and see how it looks. good job btw.

Thanks!

Definitely need more flow when running a big power-adder. Learned that last year with the big nitrous shots (85 gave way to 150 eventually...) The bap seems to work great to make the v6 stock pump keep up.

[98GREENGLOW]

Mine jumps straight up to. Nonthing gradual about it.

So you ran with bigger injectors ad you were still lean....I have the walbro 255 lph and I run way to rich on the stock injectors.

But I should have it perfect for tonight. Im gonna shoot for 75 fuel psi at 10 pounds of boost. Hopefully that will be about right.

changing the tire psi dose work somewhat.

On my 18,s I could land 2.3's almost every time. With the 15's I would spin all through first and second resulting in 16 second times acoording to my FX2 vrs 14 second times with the 18 having way better traction.

After letting y tire pressure down from 30 to 17 psi I was able to get into the 14's once with the 15's accordind to my fx2. AND IT STILL SPINNED SOME THROUGH SECOND GEAR.

Tonight Im gonna put it at 16 psi and let her rip.

Before I got the blower I could rev up to 2 grand and launch with all my power. Now I have to launch at 1500 rpm's and lightly apply gas just to get a 2.3 60 ft. Anything higher than 1500 or stumping the gas will result in 2.7 60 fts.

I cant wait till I get a LSD and some slicks. He he

Keep me posted on the battle of air vrs fuel.

[John_D.]

Here's the latest. Watched the fuel pressure throughout the rpm range, and although the bap (set at 35%) held 80psi on the initial hit, it was still dropping to 60-65psi on top end. So I cranked it to max (50%), and I'm holding 80psi fuel pressure all the way up now.

Now to log it and see what the o2's say... [img]smile.gif[/img]

If it's good, then I'm racing it Saturday afternoon with some of the locals going up to Beech Bend dragstrip in KY!! :D

I think I'll put my 16's back on for that. I have the stock tires on the fronts, and some bfg drag radials on the rears.

[98GREENGLOW]

I messed with my fmu bleeder and couldnt get quite wat I wanted. The pressure would go from 60-70 between 5 and seven pounds of boost (about right) but would jump up to 95 once it passed 7 psi.

Im gonna try a 3 way bleeder instead of the 2 way now. I want to have no more then 75 fuel pressure at 8 pounds of boost or Im not going tonight.

[98GREENGLOW]

I went and changed it to a 3 way bleeder and it helped slightly. At 6-7 pounds my fuel is 75-80, at 8-9 pounds my pressure is about 88.

Not what I wanted but it feels decent and I clocked a 14.8 with the top down at my spot just now.

Im also able to pull 2.3 60's with the 15 nch rims now. Im sure when I let out another pound or so at the track I should be able to get some 2.2's or maybe better cas I only launched at 1700 rpm's to get that 2.3 just now.

It looks like well both be hitting the strip soon, GOOD Luck

[John_D.]

Sounds like it might just work. [img]smile.gif[/img]

Keep us posted. My two passes will be about 1pm on Saturday afternoon. So I'll come back with some results too.

[98GREENGLOW]

NOPE.........88 fuel psi is way too rich...I ran one time and pulled a 2.5 60 ft and a 15.8 et at only 86 mph.

When the fuel is right I can trap 91-94 (on just a tuned 6 pounds of boost)mph on average.

The problem is that I can only get the fuel right if I only run 6 pounds of boost. I already no that my 6 pounds of boost is good for a 15.1-15.4 on average coming over a second down from my NA of 16.4. Now I want to see what 8-10 pounds can do......But the fuel just rises like crazy with my boost, and causes me to loose power big time.

I ran that one time tonight and said screw it. Trapping at 86 means the current tune is NO GOOD...Back to the drawing board..........

Im gonna have to let the dyno figure this one out. Ive tried a pcv valve and 2 different bleeder valves. Anything above 6-7 psi results in 87-100 fuel psi.

I might just try and run without the FMU next time. My fuel psi stays around 60 then thanks to the walbro 255.

[98GREENGLOW]

This reminds me of when I first got my powerdyne....I didnt have my fmu hooked up cause the person who sold it to me said he didnt have the connecters....

I ran it like that and couldnt do any better than like 15.7-15.9, coming down from my 16.4 NA. I was dissapointed.

Then we got my FMU hooked up and the stupid stock fuel pump died. I changed it out with a walbro 255 and that one lasted like 6 hours and then died prematuely. I then got another free one to replace that one and got everything hooked up and my fuel pressure anound 70......

Went to the track and ran a 15.1 at like 90, coming down from a 16.4 at like 85 or so.

It was all worth it in the end......Im gonna just keep telling my self that about the 10 pound intercooled set up.

[98GREENGLOW]

I think I got it....I used a different pcv valve and now my fuel pressure goes from 60-70 at 5-7 pounds of boost and jumps to 80 at 8 pounds of boost. Im sure that 9 or 10 pounds will result in 100 fuel psi, but atleast I should be good up to 8 pounds....Hey it's a start....