i just put my vafc in my prelude and i need some help with what i should be doing to tune it.... i have an h22 with intake, full exhaust, adjustable fuel pressure regulator, and a walbro 255 lph fuel pump.... right now my fuel pressure is at about 48 psi at idle and i have slightly tuned my vafc and the engine light came on for an excessively rich reading from the O2..... i have no idea what fuel pressure i should be at with my few mods or how i could make my most power....any help or suggestions would be greatly appreciated
V-AFC tuning help!!!!
- Thread starter 96_vtec_lude
- Start date
* your fuel preasure at idle is too high not sure exactly what it needs to be for your application but almost 50 psi at idle im almost positive is too high
* when you say you "tuned it" im going to assume that you increased fuel flow even more hense the code.. dumping too much fuel is useless.. more fuel does not equate to more power unless the motor is built to need more fuel... runnign overly rich will ACTUALLY make you slower..
* you can not drive way tune a vafc.. to find the settings that YOU need you have to bring it to someone with a dyno who knows what they are doing. this will allow them to adust things like fueling to make the most power without running rich or lean..
* reset the VAFC, find out the correct fuel preasure, reset the ECU and clear the code.. then wait till you can get the car tuned... the vafc with the STOCK settings should not cause you a problem.. keep in mind you still have to follow the prompts to set it up.. just dont change anything like fueling
* running so rich that you are throwing a CEL may also end up causing you to foul your O2 sensor.. that fuel pump is also noturious for over fueling and MAY require a regulator that has variable size return orfices in it to accomedate for the larger pump..
* when you say you "tuned it" im going to assume that you increased fuel flow even more hense the code.. dumping too much fuel is useless.. more fuel does not equate to more power unless the motor is built to need more fuel... runnign overly rich will ACTUALLY make you slower..
* you can not drive way tune a vafc.. to find the settings that YOU need you have to bring it to someone with a dyno who knows what they are doing. this will allow them to adust things like fueling to make the most power without running rich or lean..
* reset the VAFC, find out the correct fuel preasure, reset the ECU and clear the code.. then wait till you can get the car tuned... the vafc with the STOCK settings should not cause you a problem.. keep in mind you still have to follow the prompts to set it up.. just dont change anything like fueling
* running so rich that you are throwing a CEL may also end up causing you to foul your O2 sensor.. that fuel pump is also noturious for over fueling and MAY require a regulator that has variable size return orfices in it to accomedate for the larger pump..
oc_civic said:
i know everything you just told me, what i was wondering was if anyone could tell me what they have their settings for or if their is a website that anyone knows of to check things like fuel pressure or recommemded settings for the vafc....i know you cant "fine tune" it without a dyno but their is also street tuning a car which is not as effective but i'm sure lots of people have done it before and gotten close enough until they could get it on a dyno... i was wondering the settings to run for about two weeks till i get it to a dyno cause their arent a whole lot of dynos available in my area.....
the answer is simple.. run on the settings it comes with back the fuel preasure down.. ill say it again.. regardless of what anyone tells you.. there are so many factors that effect engines and combustion. there is NO way to have a "generic setting" you just need to get that portion of it tuned while on a dyno.. i mean think about it.. i have a vafc.. its on a y8 with nitrous.. my settings.. useless to you.. PLUS factor in the potential over fueling of the pump you are using and adding ANY additional fuel will more than likely generate a cell.. the car is not running right BEFORE the vafc.. so there is no way to tell you what the vafc to (even IF it was possible to just use other peoples settings).. TYPICALLY you can safely adjust around %5 or something like that.. BUT whats to say YOU with YOUR situation need to.. and at what rpm.. the ONLY way you would know is if someone had your IDENTICAL setup with your SAME over fueling issue.. and you will spend the rest of your days trying to not only find that person.. but find that person running WELL with a vafc.. i was in no way trying ot be an ass to you.. just telling you the only GOOD way to do it..96_vtec_lude said:
yea it just seemed like you were trying to talk to me like i was dumb or something....what your saying is common sense and i was just looking for suggestions which apparently this site isn't good for those.... not good ones at least....oc_civic said:
generally you get a stupid answer to a stupid question.96_vtec_lude said:
What hes told you is right, and if you knew it as "Common sense" you would of know to not ask the question in the first place.
My vafc is set to factory specs, minus vtec engagement, but even that is close... 5500rpm instead of 5800rpm, and when i run on the track i usually set it to about 5300rpm.
get a civic repair book ( i think its helms) and look up fuel pressure and it should tell you the stock fuel pressure you should be running at. with only basic mods, stock fp is ok.
edit: actually you want to get a prelude repair book or even search it up on google
edit: actually you want to get a prelude repair book or even search it up on google
96_vtec_lude said:
i replyed to your questions.... i gave you the BEST answer you can get "dont f**k with it till you have dyno time" thats HONESTLY the answer.. in fact..
http://www.apexi-usa.com/support_faq.asp?id=14#results
so yeah this site is pretty good for CORRECT answers.. maybe you were looking for someone to spew off some BULLSHIT.. someone to tell you "yeah at 4k rpms go + %25 fuel" but that would be USELESS (the car would probably run rich bog and throw a cel but thats not even the point)..Apex said:
to say it again..
THE ONLY WAY to CORRECTLY tune a VAFC is on a DYNO.. thats it.. street tuning? GARBAGE...unless you are EXTREMELY lucky.. it will NOT help you..
honestly, tuning with a vafc perios is garbage. with the availability of programs such as crome and uberdata, i cant fathom why someone would buy something like a vafc. this doesnt apply to those of you who've had yours for awhile. and street tuning can work fine, you just need a wideband to do it. by the way, most stock hondas run 42 psi of fuel pressure.