fsae_alum

If anybody tries to tell you that an O2 only affects highway cruising.....punch em square in the face. I had been told that repeatedly, and I believed it. I finally got around to replacing my original one (42K miles) and all I can say is HOLY CRAP! What a difference. Not only does it help highway cruising, but it greatly helped acceleration. Everybody said that WOT acceleration will make you smile.....well, it wasn't happening in my car......until after I replaced the O2 sensor. Now the car IS like a rocket!




Oh yeah....if anybody tries to sell you a Trust downpipe, pass on it...... regardless of how inexpensive it is! Turns out that when using the Trust downpipe, the OEM and replacement O2 sensors interfere with the bracket that connects the frame rail to the shock tower.

Bacon

iTrader: (12)

Amazing, some how you ended up the the only fd that uses an open loop fuel map during aceleration.
unfourtnaetly all of us have the other ones that use a SET fuel map for aceleration. (only references the 02 sensor @part throttle)

Did you disconect the battery by any chance?

Gadd

Ok.. I will. The O2 senor has nothing to do with acceleration.


I'll post as much documentation as you'd like, including a/f logs showing feedback operation.

Maybe you car is just happy your doing some maintenance on it.

fsae_alum

I don't understand it either man. Doesn't make sense to me but it is one HELL of a difference. I didn't disconnect the battery. I removed one O2 and replaced it with another one. That's pretty much it. I'm baffled too. Don't really care as long as it works though!!!

Provide all the documentation you want....fine with me. I understand where you're coming from and I don't understand it either but it has made a night and day difference in my car.

fsae_alum

Yeah...it's amazing how all 3 of us didn't look at the FSM..........until now. I'm not dinging either of you because I didn't look at it either.

Please refer to the following pages in the FSM to see how the O2 sensor is used by the ECU to affect acceleration:

Page F-172, Pin 3C....it lists the voltages for the O2 sensor as a function of acceleration.....hmmmm.....

Page F-184 where it states that the voltage is 0.5-1.0V during acceleration. Doesn't say that the ECU reads it, just that it is the O2 sensor supplies it. However, if it's not used, why does it list the values for acceleration and why do they have you check the voltages while the engine speed is increasing?

Page F-193 where it states on Item 26 of the Troubleshooting Guide Table that the Oxygen Sensor can be a cause of Poor Acceleration

Page F-195 where it states on Item 29 of the Troubleshooting Guide Table that the Oxygen Sensor can be a casue of Hesitation/Stumbling on acceleration.

No apoligies necessary!

Bacon

iTrader: (12)

The ecu reads it to a rpm/ throttle percentage point, I.E 35% throttle or 4200 rpm whichever happens first (dont quote me on the values) , it does not use it under WOT. the 02 will provide a refrence signal under acel which the ecu will use untill it reaches this point. Hence how you can hook up a wideband and watch the fuel map stay dead on under WOT, or @ higher rpm's.

acel is different than WOT

And if you watch a wide band or a 02 gauge you can watch it bounce around on the highway or part throtle as the adaptive fuel strategy alters the mixture for best performance/fuel ecomony

Gadd

Thats good because your not getting one from me.

I will concede if your o2 sensor is totaly stuffed you may experience a momentary hesatation as the ecu switchs from closed loop to a fixed map. But Replacing the o2 sensor will not turn your car into a "rocket".

Please refer to the following chart, the ecu only looks at the output of the o2 sensor in the "feedback zone" a very small movement in the pedal will put the ecu out of closed loop.


The voltages shown it the FSM are diagnoses purposes only

Marek

iTrader: (2)

Perhaps your engine was reading a code from the O2 sensor causing it to go into a "limp home" protection mode which if i remeber tweaks the A/F super rich. I don't beleive boost is effected though.

fsae_alum

What manual is that out of? The online 93 manual that I have doesn't have that image on any of the 250 pages of the Fuel and Emmisions section. WTF? Is that the 94 manual?

I was just kidding about the apoligies. Turns out that I suppose we were both somewhat wrong and both somewhat right.

Gadd

It is from the 93 Service Highlights. nashman69g has my copy of it and is scanning it and will post it soon ( right nashman69g? ) Lots of good info.

fsae_alum

(In my best Cartman voice) Ohhhhhhh rainbowww...

RE.Amemiya.FD3S

Guys.. just a small question please,

my fd's O2 sensor wire is cut and the check engine light is on, i didn't notice that the wire is cut until now!!!!!!!? when i accelerate, it sometimes pulls late and sometimes gives me power loss! and it has a weak reponse when i accelerate.

but i already got it a used OEM O2 sensor from another damaged 13B engine and i am having it installed next week.

what will happen if your drive your FD without the O2 sensor?
because in some cars like Honda, it's sometimes okay to disconnect the O2 sensor.

wizzurp

iTrader: (6)

You will probably just get wretched gas mileage as it'll probably default to a rich mixture to make up for the lack of signal input from the sensor.

RE.Amemiya.FD3S

as for the fuel, it consumes LIKE HELL!!! so it will be O2 sensor for sure, because also when i accelerate and if it pulls i can smell the fuel.

1QWIK7

iTrader: (33)

If you can smell the fuel when you accelerate you have another problem.

RE.Amemiya.FD3S

Yes, the problem was the Fuel Pulsation Damper.

sc_frontier

iTrader: (3)

Also, running rich like this can shorten the life of your catalytic converter as it gets very hot.

XLR8

iTrader: (52)

As well as the life of your engine.

86rxNa

I changed my o2 sensor and now it spits out the code for it like its bad.

RE.Amemiya.FD3S

Guys, i am worried about this used O2 sensor that i got from a damaged 13B '93.

So i decided to buy a new one, which brand? Will Universal ones work fine? so far i got NGK, Bosch, APW International, Delphi, Denso...etc

I think Denso is better, Any suggestions?

Thanks