DelSolSi93

Ok I searched and i found lots of posts on how to install and wire VAFCs but my questiong pertains to the Air/Fuel settings. Basically I want to know how low of a % I can set it to without causing damage to my motor, I know this will make my car slower, etc but its only for daily driving to increase fuel economy The guy at the shop said no leaner than -10% anyone have any experience with this or can tell me whats a safe # to set it to without risking problems. Also on the flip side how much could I increase the fuel to add performance when driving hard? Thanks in advance

94_HATCH

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DelSolSi93 &raquo;</TD></TR><TR><TD CLASS="quote">Ok I searched and i found lots of posts on how to install and wire VAFCs but my questiong pertains to the Air/Fuel settings. Basically I want to know how low of a % I can set it to without causing damage to my motor, I know this will make my car slower, etc but its only for daily driving to increase fuel economy The guy at the shop said no leaner than -10% anyone have any experience with this or can tell me whats a safe # to set it to without risking problems. Also on the flip side how much could I increase the fuel to add performance when driving hard? Thanks in advance </TD></TR></TABLE>

So you want to lean out your car for better mileage? You using a butt dyno or have something to actually base #'s on?

Luserkid

Do you have a wideband? If no then youll just hurt the motor and maybe even melt a piston. Take it to a dyno and have it professionally tuned with wideband.

DelSolSi93

no I havent gotten it dyno tuned, im running it -5% right now across the board so thats risking damage? Im sorry Im really new at this stuff, the guy at the shop that installed and stuff said I would be ok to lean it out up to -10% across the board but no more than that or it would start popping and stuff

Luserkid

Anything out of stock is risking damage, if not done properly. I understand you want better fuel mileage but what if that 5% drops you down to 11a/f or something? or maybe lower. You wont know unless if you tune it. (Stock is 14.7)


Edit: Thats why i dont like shops sometimes.... Theyll tell you anything. But truth of the matter is that all cars are different. Not every car is the same. Sure a couple of cars cand run fine without seeing a dyno and it might help, but what if your not part of that couple of cars? Better safe then sorry.

jlacoy82

Its really not worth damaging your motor over. If you are trying to save money.....its gonna be cheaper to NOT blow your motor than it is to pay for gas.

For arguments sake, lets say you get 35mpg. 5% of that is .1.75, and on an 11 gallon tank, that yeilds you an extra 19.5 miles per tank.

So with just 35mpg if you drive 15k miles a year, you'll fill a nearly empty tank 38 times.

With that 5% increase in fuel economy, you'll make 36.8mpg, and driving 15k a year, you'll fill a completely empty tank 37 times.

So to save yourself a 20 dollar tank of gas, you just went out and spent $250+ dollars and now risk damaging your engine due to improper a/f ratio.

DelSolSi93

ok let me ask this then, until i can get it to a dyno if the car seems to run fine, theres no popping, no adverse noises/performance, car runs at normal temps etc is it probably ok? I mean overall the car runs fine at -5% you can tell its slightly slower but it doesnt run any different or anything, would I see a difference in how it runs if its starting to damage stuff? The 5% decrease yeilded about a 5mpg increase, so its about 1mpg=1% so far

Luserkid

JL is right, say it is 1.75 youll save one tank of gas but at the same time over time you could be damaging the motor.

Slower doesnt always equal better gas mileage. It just means the motor is struggling.

Honestly just do this, if you think that tune is fine that you did then go to a dyno with a wideband and ask for a base dyno pull. Theyll give you 3 passes and thats it. Probably cost you about 50 to 75 bucks. And get a Wideband graph printout.

Whats so wrong with keeping it stock and saving yourself the trouble of getting a new motor?

DelSolSi93

k seems like everyone is in favor of keeping it close to stock, the other issue ive had is ever since i installed my MSD SCI kit it seemed to run rich it blows mad carbon out the back and uses 6-7mpg more of fuel than before that kit so thats part of the reason i was trying to lean it out, any ideas what would be causing this other problem?

Luserkid

If you want to make a question about whats going on with your car put everything out there. The car, the motor, whats on it, whats been on it, what you changed, when did it happen, etc. You make your questions to vague.

jlacoy82

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DelSolSi93 &raquo;</TD></TR><TR><TD CLASS="quote">ok let me ask this then, until i can get it to a dyno if the car seems to run fine, theres no popping, no adverse noises/performance, car runs at normal temps etc is it probably ok? I mean overall the car runs fine at -5% you can tell its slightly slower but it doesnt run any different or anything, would I see a difference in how it runs if its starting to damage stuff? The 5% decrease yeilded about a 5mpg increase, so its about 1mpg=1% so far</TD></TR></TABLE>

No, look at what I just wrote. On an ENTIRE TANK OF GAS, you get about an extra 20 miles. So for every gallon of gas, you are getting about 1.75 miles to the gallon more. I just did all the math out for you. If you drive 15000 or so miles a year, you will save yourself from spending money on ONE tank of gas the entire year, so you have a yearly savings of about 20-30 dollars. So for the cost of that VAFC, and dyno tuning, you would have to drive your car for at least another 10 years at current gas prices to realize any sort of savings.

You'd actually save more money now by just selling the VAFC and running on your stock fuel maps. If you drive less than 15k a year, you'd see savings alot less soon than if you drove MORE than 15k a year.

At this point all you managed to do was kill the power in your already powerless civic and increase your gas mileage by about 5%, which I already explained is 1.75 mpg, ASSUMING you already get 35mpg.

DelSolSi93

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Luserkid &raquo;</TD></TR><TR><TD CLASS="quote">If you want to make a question about whats going on with your car put everything out there. The car, the motor, whats on it, whats been on it, what you changed, when did it happen, etc. You make your questions to vague. </TD></TR></TABLE>

Ok sorry
I have:

1993 Del Sol Si
D16z6
114,000 Miles
AEM Short Ram Intake
MSD SCI Kit
Magnacore Wires
Apexi VAFC-II
2.25" Drop


I was getting 38mpg city and 42mpg highway before installing the MSD kit
after installing the MSD kit I dropped to 37mpg highway, 34mpg city which is odd because according to everyone at the shop and friends that have them its supposed to increase fuel economy. The car also starting running rich, exhaust smelled like fuel more than normal, during vtec a huge cloud of carbon was created more than normal and fuel economy dropped, there was also occasional bogging. I put in new plugs and after 300 miles of driving the were totally coated in carbon and looked old, So thats why I was trying to lean it out on the VAFC because it seemed like it was using too much fuel, what may be the problem here?

Luserkid

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DelSolSi93 &raquo;</TD></TR><TR><TD CLASS="quote">


I was getting 38mpg city and 42mpg highway before installing the MSD kit
after installing the MSD kit I dropped to 37mpg highway, 34mpg city which is odd because according to everyone at the shop and friends that have them its supposed to increase fuel economy. The car also starting running rich, exhaust smelled like fuel more than normal, during vtec a huge cloud of carbon was created more than normal and fuel economy dropped, there was also occasional bogging. I put in new plugs and after 300 miles of driving the were totally coated in carbon and looked old, So thats why I was trying to lean it out on the VAFC because it seemed like it was using too much fuel, what may be the problem here?</TD></TR></TABLE>


Man after that i would have gone back to the shop that installed it (im guessing you had a shop install it since you had a shop install your VAFC and you talk about a shop alot.) and have them fix it, take it back and give you a new one or your money back. Sounds like you got screwed.

Ditch the kit.