I was really careful with all connections, even went to go get a bottle pressure guage 1hr before the dyno session. But it turned out to be a long and disappointing day..

I was at 800psi (full tank) so i definitely need a warmer...

I put my VAFC on +5 rich and started doing runs... my first run, a cap on my fpr vacuum line burst... I was running WAAAY lean (around 18:1 for half the pull)...

I plugged up the hole with a screw... 2nd run... the connector on the fpr vacuum line burst... long story short, there was 3-4 runs where the vacuum line kept popping off.. in the end i used 4-5 zip ties and 2 hose clamps to keep it in place.

My 1st Q: Seems like when I am spraying, the fpr vacuum line has a REALLY HIGH pressure... shouldn't this be a vacuum line ?!? Why does it have pressure ?

Anyway, when I finally managed to pull off a run w/o any hose bursting off, this is what I got:



Wow... that looks good eh right ? Well, not really, the AF ratio was pretty lean, around 14.5-15...

I tried to richen up the mixture with my VAFC, but it didn't seem to do anything...

Then my car started detonating BAD... check this out:



2nd Q: Why does my VAFC not correct the A/F ratio ?

Oh... this was all on a 65 shot... I can make a few guesses:
-something is wrong with my fpr vacuum line which makes my vafc useless for a/f changes
-65 shot is TOO much for my stock fuel pump
-something is wrong with the zex control unit (i bought it used)

Can anyone shed some light ?

Oh... I tried retarding 2 degrees... as well as 4 degrees... didn't make a difference...

Oh... one more thing, i did check each plug, all show signs of running lean/detonation, but none is particularly worse than the others... i thought maybe 1 cyl was leaning out more than the others... u don't see it from the above dyno plot, but 4500+rpm, my af ratio is actually pretty good at 13... but from the 2nd plot, it clearly still shows detonation...

 

when I had the zex kit I blew the lines left and right...which is why I would never run it again...you have to clamp em down hard...

you are probably maxing your fuel pump, if your at a 65 shot and trying to add more fuel with the AFC there is probably nothing to be added.

Get a FPR and Walbro pump...did you make a run without nitrous? thats where you should start...tune the car without nitrous so the a/f ratio is where you want it. Then when you spray, more than enough fuel should be added to make a decent a/f ratio...if your good without nitrous, and when you spray your running lean, you just running out of fuel more than likely.

 

also, what is your setup? mods? engine? etc etc


[Modified by 01GSR, 4:44 PM 6/15/2002]

 

i'm guessing that's the 4 cyl. right?

 

ya, i tuned it NA first... then when I was going to spray, i richened up 5% all across the board...

i've got pretty much every NA bolt on except exhaust... cam gear, ign adv/retard computer, vafc, pulleys, intake, headers,... plugs... what else ?

my cam gear gave me a lot of top end...

One thing I wasn't sure of is this... the VAFC modifies the MAP sensor signal, I am guessing that the ECU uses this signal to control how much fuel to "inject" via the injectors. The actual fuel pressure stays the same ? So even if the injectors are max'ed out, and i'm not getting enough fuel, then if I just add a fpr, shouldn't that help ? Then if my fpr is maxed out and it still doesn't help, then its time for a walbro ? is my logic correct here ?

Oh ya, I looked at my dyno closely... my af ratio for the top graph was around 15... lean, but not that bad...

my 2nd graph, i was like 17... very lean... so i know what the problem is...


[Modified by TWG, 10:01 PM 6/15/2002]

 

1. dont richen with the afc when you spray...thats overkill

2. get an exhaust

3. get a fuel pump...you have enough bolt ons that you do need a fuel pump...get one before you spray again

 

don't richen ??? but the wideband O2 sensor was at like 17... WAAAY lean...

I wouldn't thought the 6th gen can handle a 65 shot...

Do I gain anything if I get a fpr ?

 

you wll need an fpr
you will need a fuel pump
dont spray so low in the rpm range, thats asking to be clowned
the afc is just an injector controller, and
if your not delivering an adequate flow of fuel to the injectors only so much can be done by the vafc.

i am in the process of doing a complete fuel system for my 95 stay tuned...

 

Dude, you need bigger injectors.
that's the <U>real</U> solution to your problems.
you can spend money on a FPR, high flow pump, and all that other crap and still
have trouble with the mix.
Save yourself the money and headache and get 310 cc injectors or bigger.
you have the APEX already so use it to it's full capability by getting injectors.

But then again, nobody learns from others' experience.

 

yeah larger injectors are great
but they dont mean squat if you cant deliver the necessary volume of fuel to them

 

sigh... more stuff i have to buy...

so which should i get ? inline pump or in tank ? the Walbro 255 is very popular... but most shops around here are only selling in tank ones...

 

Volume is not the issue here.
With the stock injectors, Volume is a factor of Pressure.
Meaning if you want more fuel you increase the pressure.
If you go with a larger injector, you do not need to upgrade the pump to deliver more fuel.
You will be taking advantage of having an injector that doesn't need to work with high pressure to deliver more fuel.
then you can regulate the injectors' pulse width with the VTEC controler and you have a system that runs on stock pressure, but delivers more fuel, consistently and reliably

But I say it again, nobody learns from someone elses' experience.

 

get the walbro high pressure 255 in tank

 

$113 shipped to your door from http://www.autoperformanceengineering.com

 

I don't think injectors are necessarily your problem. Then again, I'm not richening up the mixture using my V-AFC, but instead have an auxiliary fuel line for my nitrous spray. Damnit, I still need a friggin scanner to scan in my dyno charts. They really are in my car... can anyone help at all? I have a fax machine here at work and would be glad to fax my dyno sheets to somebody if they could scan them in for me.

 

Hey Wayne,

Your numbers look good, but too bad you're having so many problems tuning it. I'm kinda glad you're doin this though cuz I wanna run a bigger shot (if I ever go N2O)... so I can learn from your mistakes

How did Norm do with this setup?? did he have any numbers??

Good luck!

 

thanks for all the help guys...

100 for a walbro is cheap... i've been getting quoted 150 to 300 around these parts...

I've also gotten some useful info, I was using the VAFC to richen up a lot, say 10-15%, I've been told that it could be that the MAP signal is being altered too much and is instead reading more than atmospheric pressure, which would confuse the ECU which would then try to shut down the fuel...

I'm going to put in a bigger fuel jet and/or reduce my shot to 55 to see how things work out... then maybe i'll get that fuel pump...

Ian, ya, I realize a lot of peeps on TAC are chickenshit... not willing to take their own risks... :D j/king bud...

Norm only ran 55 shot...

 

Do you have a fax / scanner? I'd be happy to show you what F22B1s are capable of.

 

I'm looking at that web site for fuel pumps..

I was thinking on getting the walbro 255 high pressure pump.. my only concern is that under non-WOT conditions, I assume that my fuel pressure would be much higher than stock, so that probably means my injectors would have to have really short pulses..

is there any limit to how short these pulses can go ? I can prob make due with a 190 lr/hr pump but just in case...

 

correct, i meant to say mass/flow, regardless those retarded banjo fittings in the stock system will only flow so much.

the stock injectors already operate high in the duty cycle range
depending on the fuel needs of the motor a stock pump will be sufficient but the fuel line needs to be replaced with one that move the fuel effectively

and increasing fuel past a certian point will not necessarily result in more fuel, as the fuel flow drops off with increased pressure

and no, they dont listen to experience here, soon you are doomed to be as jaded and grumpy/irritable as i am

 

i do man...if ya want to fax it i can scan it in....

 

Poopy... I just left work. How about I fax it to you tomorrow morning when I get to work? IM me with a fax number and a good time for me to fax it to you...

 

garg damnit!!!!!!!!

 

if u still need to fax it to someone, let me know...

I reset all the VAFC settings to 0, and did some runs.. NO DETONATION!!! YA!!

What a kick... kinda like VTEC kicking in... but more!!

Time to start tuning for a 75 shot..

How much are injectors ?




[Modified by TWG, 9:25 PM 6/17/2002]

 

you can get some prelude vtec injectors for about $100 for the 4 of em. They should be plenty for your fuel needs