for the past few weeks my car has been acting up, its a 2000 Si with a JRSC@6psi, fuel pump, vafc, boltons, gauges etc...ANYWAY the same week we installed it, I had it dynoed and tuned and its been running strong ever since, but like I said lately the car has been acting up. My friend (who knows more about the VAFC than me) was going through looking at all the settings and stuff and he said that they all looked to be at zero (which i know it should not be because at teh dyno they used the vafc to pull out fuel) and my tps reading is only reaching around 4.1xx volts when he says its supposed to be 4.5 at least. My question is, is there any way for the vafc fuel setting so get re-set if I have never changed them? I mean, literally the only thing i have ever changed is the vtec point, which the guy showed me how to do and that shouldnt affect the fuel settings right? I dont know, i mean i guess i could take it back to the dyno and have them look at it, or just make a run and see what the a/f is and hp to know if its messed up or whatnot, im just running out of things i can check and all signs point to the vafc as the culprit to my probelms. If anybody can answer any of these questions/problems and possibly post up some of your settings if you have a jrsc'd Si so i can see what they might look like if it was correct...I would apreciate it, Im lost

TIA

Brian

 

oh yeah, ive had it for 8-10 months, so its not like we just installed it last week or anything....if that helps eliminate any questions about that....

 

Hey Brian:

Define "acting up"? Does it hesitate at a certain rpm/throttle position? Usually your TPS voltage is around 4.5 volts at WOT. I am not sure if that is the source of your troubles, but the JRSC into the Civic Si can put a lot of strain on the TPS wires. You should check the connector and see how much slack you have there (if any). I ended up lenghtening the TPS wires on my install.

Does the ECU throw any codes?

Sonny

 

hey sonny, so far the only cel codes i get is for a bad cat, nothing else so far, by acting up what happens is usually around 4500 rpms the car kicks like its about to cut out but i step on the clutch and it continues to run, and it may work fine for a while, then randomly it will do it again. Recently, what im more concerned about is if my vafc settings were somehow re-set and my a/f mixture is wacked out that it may not be running as well as it should, and could possibly be running to rich or something since lawrence (from dsr) really only used it to pull out fuel as far as I know....Somethinhg I just thought of, When it sputters the CEL Blinks and then stops after I bring the rpms down, but doesnt stay on after that....Elton (dont know if you know him) said it was probably something to do with the vafc or the map sensor, so i have been driving around with it on sensor check but i really dont know what the map reading is supposed to be, todd just said to watch it when the car trips out and see what it does. Its strange, like i said todd seems to think that the vafc settings are all at default settings, but the number of cylinders has not changed and the 6 in 6 out setting for the sensors,so its not like it was initialized otherwise i probably would have a toasted ecu.... and i dont understand why my tps is not reaching 4.5 like it should be.....grrrrrrrrr

any ideas? thanks sonny for responding.


[Modified by The AntiRice, 5:23 PM 7/26/2002]

 

Brian,

Since you have no way of datalogging while the car is running, it really isn't possible to see what CEL code is being thrown. So, I think you might have to try to correct this problem using process of elimination.

I would have to say that the most likely culprit is probably the VAFC. For now, I would take it out of the picture. That's probably not what you wanna hear, but disconnecting it isn't too bad. You only need to modify the wires that pass thru the VAFC and not the wires that the VAFC just "listens to".

The VAFC listens to (ie, taps into):
1) Power
2) Ground
3) TPS
4) ICM aka RPM

The VAFC modifies:
1) VTEC
2) MAP
3) VTM

The kit should have provided you with connectors that allow you to bypass the VAFC. Plug the VTEC from the engine back into the VTEC going into the ECU. Same with MAP and VTM. In this mode, you'll essentially be bypassing the VAFC without having to completely take it out.

If you're worried about boosting without the VAFC, I wouldn't worry about it too much. Like you said, the engine was running really rich and Lawrence only used it to remove fuel. You won't really hurt anything (except power) by running without it and it will allow you to eliminate some variables in your setup.

Sonny

 

Ok here is also another option....I had one in my Si for a while and had the same problems at 6 grand it would like cut completely off. You need to double check and make sure the VTM wire has been wired up. If you have had it for around a year that means you have the same book i had and it says to leave the VTM undone. But if you check the Apexi update on the webpage...then it will tell you different. Mine wouldnt store memory also...i had a bad unit....send it back or take it to your local Apexi dealer. Keep me posted.

 

both helpfull information, Does anyone know for sure that the vafc is SUPPOSED to keep the settings if the battery dies or if power is disconnected (say to clear a cel?) we kind of tested it last night by changing something on the vafc, then pulled the neg battery to see if it would clear it, but it did not, however like i said the fuel settings are at factory settings...
I'll have to check the instruction manual i belive it came with an extra page that may be the *update* that you mentioned, ill also have to check how its installed but would it make sence for it to work flawlessly for so long and now all the sudden be acting up....? thanks again for reading...

brian

 

also does anyone know approx what the map sensor voltage should be reading (min/max) etc? because i already know now the tps is not showing the correct voltage, just wondering for future ref.

brian

 

did you go to etc. and hit initialize????? if you did it will go back to 0!!! and i think it resets if the battery cable is removed....just write down the settings or remember them.....that sux your car isnt running well.

 

The max voltage that the MAP sensor can send to the ECU is around 3.0 volts. If it goes any higher than that (it can...it's a 5V sensor), the ECU will throw a code. At WOT, I saw around 2.8-2.9 volts on my car.

Sonny

 

well, I have never went in and changed anything, and most certainly I never re-initialized it because i knew someone that blew an ecu from doing that because it defaults to a 6cyl setting and it poped the ecu....It still retains the super important settings i guess, maybe it just forgets the fuel settings(which IMO is stupid as **** that it would remember where the vtec was set but not fuel tuning)

anyway, thanks sonny for all the input, I guess Ill just have to mess with it, and worse comes to worse get it re-dynoed (sigh) and go from there.

Brian

 

disconnecting thr battery will not make it lose memory. You can disconnect the VAFC and you wont lose memory

 

thanks guys, I guess its possible that I have a bad vafc....dont understand why it would work perfect for so long and then not but then again im sure stranger things have happened. The good thing about all this is that the VAFC carries NO warranty whatsoever, so if it is defective its a paperweight. The only thing I still do not understand why its happeneing is the car randomly hanging up in the 4krpm range....My setup is fairly mild and i would say someone must have an explanaiton for it...I dont know, and I dont know who else to ask I figured if anybody would know for sure it would be someone here. Ah well

 

I've have resetted my ECU due to codes for over 20 times and the settings on my VAFC still remain the same. The only way to reset the settings on the VAFC is to go into initialze and while you're in there turn off ignitaion.

I don't not sure if the VAFC displays TPS voltage, 02 voltage or what.

 

I leave my car stored with the battery disconnected (for upwards of three weeks at times) and the VAFC never forgets a thing.