Just got back from dyno :( - Honda Forum / Acura Forum

KiddEng · 08-23-2002, 12:53 PM

aiight just got back from the dyno..and i have yet another problem..it seems that it pulls all the way up to redline...but stops making power after 4,4.5k im running the v-afc but vtec controll not hooked up. the tuner said that the vtec control is still messing it up after that point and to use a S-afc instead. here are my dynocharts..u can see im making plenty of torque..just the hp #'s aren't there at the top end.

take a look and let me know if u guys think its really the v-afc or not...im pissed...

laters

SoFlaGS-T · 08-23-2002, 01:29 PM

wow... that cant possibly be the afc... its just something wrong...

KiddEng · 08-23-2002, 02:13 PM

Quote:

Originally posted by SoFlaGS-T
wow... that cant possibly be the afc... its just something wrong...

thats what i was thinking...if i didin't connect the vtec control wire..would the v-afc still use that vtec point to adjust be4 vtec point and after vtec point?

i was looking at the fuel curve and its steady at 12.5, but when it gets up past 4.5k the fuel curve will dip down...indicating that its getting too much fuel or being rich. we tried adjusting every on the afc to compensate for this..even jacking up the vtec to 8k so it'll not send a signal..and leaning it out at the 4.5k rpm range....but it still seems to get too much fuel...

zcsohc · 08-24-2002, 11:01 PM

So you weren't running a stage colder plugs????? If not its detonation. Don't keep running it like that or it probably will blow. Goodluck

Sunder · 08-25-2002, 01:41 AM

Yeah,

Without being a mechanic, that graph looks totally psycho to me. I know that normal power/torque curves don't make shapes that look like it came from a seismic station smack bang on san andrea's fault.

I've seen VERY mild detonation being recorded on a dyno, and it make shapes somewhat like that, only much smaller. That is the power jerks up and down all over the place, and takes an overall average slow dive downwards.

Try running colder plugs as zcsohc mentioned, and pump lots more fuel in the higher end. 4.5K RPM, is probably when you're starting to approach full boost, and your engine is probably leaning out, because the fuel settings are still for a NA car? (That's just a guess)

EDIT. Just re-read your post about running too RICH... Weird... Maybe it's the AFR not reading correct mixture? Dunno. I elegantly bow out before I'm flamed...

bmm89 · 08-25-2002, 08:37 AM

a drop-off in the high revs does indicate too rich condition, i had the same problem on dyno, but mine was steady, your "earthquake" condition does look like some vtec problem... check that first, and make sure the solenoid is actually engaging despite what the vafc says.

themi6group · 08-27-2002, 02:05 PM

man i was just checking out your dyno. the problem isn't your vafc unless it was hooked up wrong and apparent. otherwise it looks like your turbo or piping is leaking and not holding boost. look for the pressure readings on a dyno chart. you should've received some. i highly doubt it's your fuel delivery because even with too much fuel it'd still look different. it wouldn't sink. you're not using the black box are you? don't if so. since you're getting plenty of fuel, it's good. take a good look at your turbo and components to include wastegate and everything.

KiddEng · 08-27-2002, 02:29 PM

im running 1 stage colder, the vafc is hooked up right minus the vtec control wire...i found out that was causeing me not to rev past 4k be4..so i disconnected it and let the ecu handle vtec and its reving fine...i do know the top portion of the rpm range its gettig too rich i think maybe 8:1 after 4.5k instead of 12.5:1.

also it was holding 6psi all the way up to redline so i think the components and turbo are working fine...

also when the tuner let off after a pull my car would back fire like a mofo as it reved down...

zcsohc · 08-27-2002, 10:55 PM

Take off the vafc and just run the fmu, then you at least know that its not the vafc.

Sunder · 08-28-2002, 02:54 AM

Quote:

Originally posted by KiddEng
im running 1 stage colder, the vafc is hooked up right minus the vtec control wire...i found out that was causeing me not to rev past 4k be4..so i disconnected it and let the ecu handle vtec and its reving fine...i do know the top portion of the rpm range its gettig too rich i think maybe 8:1 after 4.5k instead of 12.5:1.

also it was holding 6psi all the way up to redline so i think the components and turbo are working fine...

also when the tuner let off after a pull my car would back fire like a mofo as it reved down...

So why can't you run closer to 12:1 all the way? VAFC computer doesn't allow that? I just found out that extreme over richness causes detonation as well, which could explain the shape of the curve. Over rich also causes back firing, because the plugs can't ignite the fuel properly. Too dense or something like that.

Also, isn't the purpose of an FMU made redundant by VAFC? I thought a FMU was to increase fuel proportionally to boost. Is it being tricked into dumping more fuel into there than necessary? What if you removed the FMU and carefully tuned using the VAFC only?

Just my $0.02 worth. (GST/VAT not paid)

themi6group · 08-28-2002, 05:39 AM

Quote:

Originally posted by Sunder

So why can't you run closer to 12:1 all the way? VAFC computer doesn't allow that? I just found out that extreme over richness causes detonation as well, which could explain the shape of the curve. Over rich also causes back firing, because the plugs can't ignite the fuel properly. Too dense or something like that.

Also, isn't the purpose of an FMU made redundant by VAFC? I thought a FMU was to increase fuel proportionally to boost. Is it being tricked into dumping more fuel into there than necessary? What if you removed the FMU and carefully tuned using the VAFC only?

Just my $0.02 worth. (GST/VAT not paid)

no the fmu is really a fuel pressure regulator. you need one to increase fuel pressure. the vafc mainly controls how much fuel is to be dumped where and when in the rpm band.

turbo-kits · 11-24-2004, 06:53 PM

What kit? Is the ECU throwing any codes?

Do you have the missing link?

Jesse @ Turbo Kits.com

FasTraxSi · 12-02-2004, 10:20 PM

I can't see the dynocharts.

What is your timing or a/f like?

KyleRekCivic · 12-03-2004, 12:15 AM

FMU is mainly used with stock injectors. V-AFC (vtec-air flow converter) is used with larger than stock injectors. also, an FMU calibrated to 12:1 fuel/boost ratio shouldn't really be used on anything but stock injectors and really isnt that safe for over 7psi of boost or so.

Kyle R