I recently installed the VAFC hack on my 2000 SI and I seem to be having problems. I have a Walbro 255 pump with a AEM FPR set at 29PSI(idle)/39PSI(static), I have disconnected the boost dependent regulator, eliminated all check valves and set the values to -35%(1000-5000) & -34% (5500-9000), retarded the timing by 2degrees and use BCPR7ES plugs. The problem is when I am WOT at around 6000 I hear pinging. I am scheduled to dyno the car next Monday but I would like to get the car to stop pinging before I strap it to the dyno. Does anybody have any suggestions? Should I take more timing out of it?

 

That fuel pressure seems a tad low.

 

What does everybody else have there fuel pressure set at??

 

i thought stock gsr fuel pressure at idle was like 53psi?

 

and that retard is a bit low for 9psi...most run close .75 per PSI...so it should be around 6.5-7 degrees total retard...just IMO...

 

Retard your timing at least 7 degrees at the dizzy. Look at a graph of your ignitiion curves and you will know why. In extreme vacuum, your timing could be at 50+ degrees! Now the afc hack is fooling your ecu into thinkings its in vacuum when its in boost...

 

Take out that adj fpr and put on the stock 1:1.

 

I presume you are using 450cc or thereabouts...? I think your fuel pressure might be your problem. Use your stock fuel regulator or try changing your fpr to stock fuel pressure..

 

if he was using the 450's & a FPR he would be rich.

It seems to me he is just using the stock injectors and the AFC to hack his map sensor and not really do **** for his fuel.

but let me just second your thoughts as far as him using stock FP and run 450's


how many PSI when you start to detonate?


[Modified by T-sohctec, 5:45 PM 3/12/2003]

 

[QUOTE]
It seems to me he is just using the stock injectors and the AFC to hack his map sensor and not really do **** for his fuel. [QUOTE]

If this is the case, then there is your problem right there!! As you'd be trimming the fuel to a level below what your stock motor needs!!...even at vacuum! let alone boost . If you wanna run the hack, you'll need ideally 450cc injectors or thereabouts. You cannot run it using stock injectors

 

I am running RC440cc injectors. If I raise my fuel pressure my car idles like crap, therefore I am running low fuel pressure. Originaly I was using the stock FPR but my static pressure was 47PSI which is a bit high. therefore I swithced to the AEM FPR to lower my fuel pressure at idle. The AEM is a 1:1 regulator just like the stock FPR. What about taking some timing out. Stock is 14 and im at 12.

 

How many psi are you running? and at what psi is it detonating?

 

Imrunning 9PSI and I detonate at 8-9PSI. If i run 6-7psi it runs great but when i go to 8-9 it starts to detonate at 5500ish.

 

Double check to make sure your AFC settings are correct (ie in etc..) - sensor type, cylinder setting, throttle type setting etc...

I guess u could also retard a couple more deg..


[Modified by swlabhot, 12:08 AM 3/13/2003]

 

WOW. I am running -40%(2000-4800) and -35%(5000-8000) and I am running really rich. I check my plugs yesterday and they spell like fuel(and dark color). With the vacuum line of the FPR it is set at 41psi. I am running Bkr7E-11 gapped at .030.
Does your A/F gauge show lean when you start to detonate? I would retard timing some more and try different plugs.


[Modified by kenbdSi, 12:42 AM 3/13/2003]

 

bring up the FP to 38..i think thats around stock level...and use 450s if ur not..or higher flow inj whatever you can find. like the guy above me said, run -35 to -40% fuel on ur AFC and retard your timing...

 

put in octane booster that should fix it.. and retard a few degrees

 

Sounds good I will raise my fuel pressure to 38PSI and take 2 more degrees of timing out of it. Buy the way when I am detonating my air fuel gauge reads rich. I know this is kind of weird but I swear it is happeing. I am going to the dyno next monday and I will let everyone know what the outcome is. By the way for those of you that have 38PSI fuel pressure at idle what is your -% set at 1000rpm?

 

i imagine ur running atleast premium gasoline 93 octane or better....
if not, sounds like crappy gas is preigniting. better gas, higher level before preignition.

 

Unless the b16a2 is different then the b16a3 stock timing is at 16 degrees.
Try raising your fuel pressure to 38-42 psi and triming the extra fuel with the v-afc.
Don't trust your air/fuel ratio gauge if it's runing off your stock o2 sensor. Mine reads the same (few bars in the rich) now with my air fuel ratio at 12:0 as when my air/fuel ratio was 10.0:1 + (too rich for wide band o2 on the dyno). So al that will tell you is that your getting fuel period.....
I'm runing 9psi rite now with my timing at 14 degrees, 310cc injectors, 4:1 fmu and sfc pulling out more fuel. I had a slight ping at 5psi but fixed that by richening the air/fuel ratio up a tad at 3k rpm and 4k rpm.....
If i had to guess, I would say that your a little lean.

 

OCTANE BOOSTER! is all i can say it will make things better


[Modified by romeo619romeo, 8:55 AM 3/13/2003]

 

As far a fuel quality is concerned I am using crappy California 91. However, in the past I have put in 100octane just to see the difference and it cured the detonation (ping) problem. But as you can imagine I do not want to use 100octane all the time due to it costing $5.00/gallon. It would be nice to get this thing set up so I can run 10PSI on 91octane without any problems.

 

Are you running an intercooler?

 

Yes!! I am running an intercooler, however it is what I would concider small 18" x 7" x 2.5". What do you guys think. Also it does not matter it the weather is cold or hot it seems to ping at any temperature. For those of you rinning 38psi of fuel pressure what is your 1000rpm % set at?

 

im running 8psi on stock ingnition with the vafc and dsm 450s and im not detonating. i would put in your stock fuel pressre rugulator and adjust your idle with the afc. ps. im using a stock ford probe intercooler.

with my stock fpr im running -40 to-38 almost every rpm on my vafc. on low throttle and -38 all the way up on full throttle