gentlejax2

I will try it sunday.

bigzman

iTrader: (1)

used wd 40 and sprayed the crao out of it, as it was the original and there was 118000 miles on engine. used a couple of extentions for leverage and the the o2 socket and kept working it until it came loose. took about an hour with eveything.

gentlejax2

O2 socket is of no use to me now since the edges of the nut on the sensor have rounded off because my little air wrench messed it up. I tried by hand with lots of PB Buster and no luck...

thanks

HenryV

Hmmm - This is based off personal experience without any testing equipment, so do take this with a grain of salt.

I had a dead 02 sensor and I had the car dyno tuned @ 10psi. From 2kRPMS up it was extremely rich and was at about 10-11 on the wideband. And on the street, once the car made positive boost, it was like a great huge kick in the pants.

Same settings on the the Greddy Profec B...

Now, I change the 02 sensor, b/c I cannot stand the poor gas mileage. Once I change out the O2 sensor, the huge kick in the pants was gone, the powerband was much more linear, and I gained 1psi of boost. I assume that this is because the computer can fine tune the A/F ratio, and is running leaner, thus creating more load, which = +1 psi of boost.

And I'm sure a dyno would show this change too.

I would venture to guess that the 02 sensor does work at more then just cruising conditions.

Cavernkid

1. OBD1 all computer controlled cars before 1996, Every car with a PCM (powertrain control modual) will have a memory of some sort it can store up to 5 trouble codes i believe. 2. O2 sensor will not make adjustments until the computers sensor network says its warmed up (all the time not just cruising speed). It attempts to make the air/fuel mixture a perfect 17.5:1 Mix. Buy sensing a lean or rich condition (measures oxygen in exhaust) Hope this helps Darin

scathcart

Here's a good example of proof that the O2 sensor is ignroed at idle:
The S4 cars have a Lean-Rich adjustment screw that affects idle fuelling. If the Oxygen sensor was being used, the car would be in closed loop, and the air/fuel ratio would be hovering around stoich, using the oxygen sensor feedback to keep the air/fuel ratio at this value, regardless of input changes... so if the oxygen sensor is being used, it would ignore the rich-lean screw... yet it obviously does not.

scathcart

Your theory makes no sense.
If you were running leaner, your car would be making more power and your seat-of-pants dyno would be better.
The Oxygen sensor is completely ignored at WOT. How is this hard to understand? This is not somethign that is open to debate, where opinion matters. This is FACT, timelessly proven.
Your O2 sensor change would have had zero effect on your WOT fuelling. ZERO.

scathcart

1. RX-7's are not OBD. The S4's do not store any codes, period.
2. Single wire oxygen sensors have no way of giving feedback to the ECU that it is at operating temperture.
3. Stoichiometric value of standard gasoline is 14.5-14.7 parts air to one part fuel, not 17.5. 17.5 is crazy lean, and would damage the engine.
4. Your post was of no help.

WAYNE88N/A

Sean, I think you're being a little too conservative with the way the ECU uses the sensor inputs. The ECU is paying attention to the inputs as soon as the car is started (it won't be using them for fuel scheduling, but it is accepting the input). Proof of this is the O2 sensor code that flashes on my LED lights not long after the car is started, before the sensor warms up to operating temp. As long as the rpms are over 1700, the code will flash, until the sensor starts putting out good "warm" voltages. That means the ECU is paying attention to an active input, but can't use it yet....

You're dead on about the idle and WOT, though the inputs are there (.8v at idle inputed, and goes crazy at WOT, but mostly in the rich ranges, especially when the secondaries kick in)...

At cruise and everything in between, the ECU is trying to get the fuel scheduling to a "happy point". In 5th gear, she'll find the really "happy point", in other gears, she'll use a wider range of fuel corrections, but she's still correcting, even on acceleration, as long as it's not WOT. I'm been watching my ECU inputs like a hawk the last couple of weeks for another problem, so I speak from many hours of experience with the sensor inputs, and what the ECU does with them...