zerodrag29

I have a 88-91 b16 in my 91 integra with drag turbo. i need to know how to run the two o2 sensors for turbo application because every time i get around 4-5000 rpm it starts to do this hesitation feel , like a misfire or somethin. I am currently running one o2 sensor from my stock engine harness since the 91 integra has only one o2 sensor. Also can someone explain open loop and closed loop and how they affect the engine and what needs to be done in order to make my car run properly.

EE_Chris

Give this a read:

http://www.tech2tech.net/training/chpt_01.pdf

And if your smart, you'll notice that there are around 30 chapters. Just change the /chpt_xx.pdf to whatever chapter you wanna read.

But chapter 1 covers the basics and chapter 2 follows it up. This is with regard to your Q on open and closed loop operation.

ATurboCivic2NV

when does your vtec engage? do you have vtec? and does it run like this after the rpm's you listed? if you answered yes to the second and no to the 3rd you might be running rich when your vtec engages causing you to bog down!

hondafrk

open loop is when the computer relies on the O2 sensor reading to adjust fuel and air at warm up
closed loop is when it relies on other sensors to adjust fuel

CivicV10@18000rpm

You got it backwards. Closed loop relies on the O2 sensor for proper air/fuel ratio. Open loop relies on predefined air/fuel ratios stored in the ECM.

tinkerbell

correct.


ALSO

the answer to your question may lie in teh VTEC engagement point where teh cams swap over, a slight sorta decrease in acceleration occurs here,

look at any VTEC dyno graph...

t..

ps. do a search on "open closed loop"

fsp31

Here is one of the best descriptions of what an ECU does that I've heard. It also discusses OBD2 vs. OBD1...

>>>>
OBD2 is not THAT bad. It actually makes thing much easier to work
on if you have the right tools. As to the ECU resetting itself when you
turn off the car, this is incorrect. What it boils down to is short term
and long term fuel trim and how the computer is compensating. This applies
to OBD1 AND OBD2. Have you ever noticed that once you do mods that the rear
of the car is covered with soot. Seems contradictory to everyone telling
you that intake and exhaust mods leaning the car out. Actually, both sides
are right. When you do mods, the car is actually leaned out but. When
driving around in closed loop mode, the computer will look at the short
term fuel trim and notice that it is lean and will "ratchet" the long term
fuel trim up. If it still sees lean on the short term trim, it will ratchet
the long term fuel trim until it (STFT) is where it is supposed to be. This
computer can correct the fuel trim up to about 20% more air flow. After
this, it cannot correct. What you end up with is correction of the
low-throttle and engine-speeds by the factory ECU.
Now the trick part. What the computer learns in low-throttle and
engine-speeds from LTFT it uses to modify the tables for Wide Open Throttle
(Open-loop) even though the computer is not actually compensating as it was
in Closed loop mode. Since the computer has been seeing lean-lean-lean, it
modifies the tables for an overly rich mixture. That explains the lean and
rich syptoms that both sides describe.
Typically the mods that you do will lean the car out (make more
power) but the computer will compensate for it within a half hour of
driving. Something like a Apexi Super AFC works great for this. Use the AFC
to trim the WOT settings only and let the ECU take care of the low-throttle
and engine-speed settings. You can look at a dyno graph that has the
effects on air-fuel ratio by resetting the ecu. Not much power difference
but look at how much the ratio changes http://www.lightningmotorsports.com/images/ecureset.jpg Remember this
happens in BOTH OBD1 AND OBD2.
The main thing about OBD2 that makes it less applicable for really
high performance is that it monitors all engine parameters more closely and
this can cause problems for an all-out racer. If you go to really radical
camshafts, you will get an engine misfire code from the ECU because OBD2
uses a crankshaft speed fluctuation sensor to detect engine misfires. You
can still put cams in the car, just nothing radical enough to set the
misfire. You will get a CEL if you remove the cat since OBD2 monitors the
efficiency of the cats with the fore and aft sensors. Just go with a
High-flow larger diameter cat and you won't have a problem. We have dyno'd
some of the new V-8 Camaros and they have shown absolutely zero horsepower
gains from removing the cats (using straight pipe) on a mildly modified
car. What it comes down to is that you can't be a ham-fisted mechanic with
OBD2, if you work within its parameters, it will not give you trouble. If
you could see some of the data that you can get out of the newer OBD2
ECUs, you would understand why I am not totally against it. I have seen
(and used) OBD2 programming software for the domestic cars, and that
totally rules. You can turn off misfire, rear O2 sensors, and much more
than I care to list. As Hondata and others work through this, you will be
wanting to keep that OBD2 computer (much faster processing) as it will be
able to do whatever you want no-matter how far you want to go.

Tom (sorry for the book)
http://www.lightningmotorsports.com
<<<<

hondafrk

sorry guys, its been a while since i worked on 02 systems, I actually used to be a honda mechanic but it was late that night and my mind was all fudged up. I guess i was a little dyslexic or something