VTHokie

Took the B20 to the dyno today for the first time and ran into some sh*t that confused everyone.
First of all setup:

JDM B20
Aem Cold Air
Skunk Intake Manifold
JDM R Header
Apexi VAFC
92 LS ECU

Rolled up with +3 across the board for a baseline. The air/fuel ratio was completely off, from about 2.5 to 4.5 the ratio was ~ 14:1, then between 55-6.5 it got rich ~12:1.

So second run I added about 5% to the bottom and leaned the top end out some. Now here was the weird sh*t, the bottom end actually got leaner! The top end reacted correctly.

Playing around with it on a few more runs I have found that I can richen the mixture up but by no more than 3% before the ratio starts taking off in the other direction.

Even tried one run with all settings at 0 and the thing was still running lean.

I'm not sure what is up, pretty much everyone at the shop was stumped.

Is it the VAFC on a non-vtec motor?
Is it possibly a bad map sensor?

I dunno any help would be seriously appreciated.





[Modified by VTHokie, 1:40 AM 2/3/2002]

iceburgslim

First thing to do it check your VAFC wiring, and then have someone else check it. Remember that the VAFC wiring diagram in the manual is looking from the back of the plug, this can cause confusion on installation. Next check your VAFC sttings (your sensor type etc.) after that, I realy don't have a clue! Hopefully someoone else will have an idea. MAybe post this in the technical forum. Later!

Looose_R

do you have a vtec head? why are you using a Vafc with an ls ecu? id definately check the wiring, does it run fine without the apex unit?

VTHokie

I do not have the vtec on this motor. The VAFC is in because I needed a fuel controller and I had this left over from a b16 setup. Vtec is set at 7K so there is no chance that I will see it.

I took a look at the wiring today and everything looked alright. This is the third controller that I have done and the first time that I have had a problem.

The TB is the stock off of the B2O is it possible that the JDM OBD2 map sensor conflicts with the LS ecu.

The motor runs fine without the VAFC however this was the first time I had checked the air/fuel ratio so I have no idea what that looked like before.

Keep the replies coming

Kamin

check the AF without the vafc running.

VTHokie

Are you trying to say that there is some way that I can leave the VAFC wired up and not have it on?

Can I just kill the power to it and run it without completely disconnecting the thing?

Brian*

you cant turn it off when its wired up. if you try to run it with no power i dont think the car will run. i know mine died when it got unplugged at the connector

Brian

fsp31

It could be a fuel pressure regulator problem. Since you have an AFC to lean the mix already, you might as well get an aftermarket FPR. All the aftermarket FPR's I know of cause the car to run more rich anyway (of course). Then put a pressure guage on there and see if your fuel pressure is consistent. My bet is there is something going on between the FPR and your fuel pump.

VTHokie

Although I haven't checked the fuel pressure, I can't see how it isn't enough I mean the mixture is fairly rich on the top end. Now if the mix was lean through out I might suspect it.

The only thing that I can think to do is completely disconnect the unit and then rehit the dyno to read the ratio. That would be a pain in the *** but its the only way I will know.