I tried to dyno tune my car yesterday...b16a2 w/ drag 3. I have rc 440s and vafc w/ walbro 255lph hp intank. Btm wouldnt work so i disconnected that and set the timing to 8 and boosted only 8psi. The afc settings from 5000rpm and up were all set +50% and the a/f went to 13.9 and going towards 14s at 6000rpm, i had to let off everytime because i was leaning out.

Afc settings had no effect so i put on a 4:1 fmu. But it ran it too rich even at 13psi...only got like 212whp and 176tq. A/f was in the 10s and i was making no power whats so ever.

I got home pissed as hell that i wasted money for nothing, didnt even get it tuned...checked everything and noticed that my knock sensor was broken. Would this have any effect to leaning out without the fmu? And my btm not working correctly?? Thanks,...i need to kno what the hell is going on.

 

ttt

 

Your AFC settings are supposed to be somewhere around -40% across the rpm band for the hi and low. With it set at +50% you should have had a check engine light for your MAP sensor. I would suggest you read up on AFC hack and make sure you did it correctly. You aren't running any check valves or a missing link on your MAP sensor, are you?

 

I had all my settings at -40, -35 before i got there. I just set them to +50 to see if my A/f would richen up a bit. It didnt do anything. No check valves or missing link. I've had a check engine forever on my car so i dont really know if it threw a code. I get CEL from my second o2 sensor, its just welded in 3" piping no cat.

 

if you had it set to +50% and you had no checkvalve, I believe the ecm would have seen boost and thrown a CEL because of the MAP sensor. you have to have the negative setting in order to shift the output of the MAP...

 

The stock map will only read to about 10psi. After that, the voltage output will stop increasing= no more fuel.

 

It was leaning out even at 8psi...How do other people run more than 10psi on afc hack??? I think VTC_civic runs 12psi on the hack.


Y was the car leaning out even at 8psi?? 440s, vafc, and walbro 255hp...i thought it should be too rich with that. Could it be because of the knock sensor broken? Or something to do with ignition timing?? Thanks.

 

every boost gauge is slightly different. The stock map tops out at about 10psi, sometimes slightly higher but not much.
What is your afc set to?

 

is the v-afc hooked up right?

 

I think that you need to fix your CEL before you go any further. Get it running descent and then go back to the dyno, with a CEL your ecu is probably in some type of limp mode. Since you are obd2 I would look into getting an O2 sensor simulator for your second sensor.

 

ttt

 

I know that's what everyone says, but I don't believe that's true. MAP sensors go in 1, 2 and 3 BAR increments. Some have no output beyond 0psi, however the Honda should go to 14-15psi. I have no evidence to support this, except that it makes sense to me and I have heard of other people on here boosting 12-13 psi on the stock MAP.

 

Thats what i thought, people boost 12psi on the afc hack.

Anyways...The guy at the dyno read the boost off a line he teed in. It looked pretty accurate. The afc settings were all -40-35. Then i set them down to 0 after 5K when it started leaning out. It had almost no effect on the A/f.

 

I'm almost positive it is...it wouldnt idle correctly with 440s if it was hooked up wrong.

 

So, when you took your passes, what did you have the rpm fuel setting on the AFC set for?

Remember, the D16 flows alot less air than a B16, so you're going to run leaner if you try to run the same psi as I did.

 

ttt

 

All honda map sensors will peak at 5v output between 11 and 12psi.

Dustin

 

what's an o2 sensor simulator?

 

a few things that i can think of.....
1. if your car is throwing a O2 code your car is in limp mode and probably running really rich just from that.
2. if your knock is broken it will throw a cel and again it will be in limp mode, making your motor run really slow!
3. you shouldnt have a fmu on with the hack at all, they suggetst no upgrades, except you can run a larger intank pump like the walbrough like you have.

you need to fix your check engine light first for sure! just go get a new o2 bung welded and put the 2nd o2 in or ive heard that you can just wire the second o2 into the 1st o2 and it will work! well atleast on OBD 0
good luck

 

Yes, it is true. Once you pass the 10 or 11 psi mark, the voltage output will stop increasing = no more fuel increase. That is almost positivly why you are running lean. You never said how much boost you were trying to run, but it was more than 10psi wasnt it?
Lower your boost level to below 10, definaly remove the FMU, set your vafc to -40 across the board (making sure to get both high and low throttle, and vtec maps) and try another run.

You said you tried to set the vafc to +50 in an attempt to get a rich reading on the a/f. If you would even attempt to do this, is sounds like you do not fully understand how the whole vafc hack/mod works to begin with. Please read the entire following thread https://honda-tech.com/zerothread?id=162603
I have tried to explain it in laymans terms so that everyone would have a chance of grasping it. Its a long thread, but i beleive its some really useful info. Good luck

 

I did a dyno run on 8psi, with afc set to -20s after 5k rpm. sTill leaned out. My CEL has always been on...i made a dyno run a while back and it made decent power even with the cell. I'm thinking ignition timing is being an issue and that knock sensor.

I'll try that wiring thing, wiring the second o2 to the first.

So could u go past 10psi on stock map with a missing link or check valves?

Thanks for all the answers...

 

REad it, thanks man..i have a more understanding of it now..