Matt
Admin
Admin
| Posts: 485 |  |
|
02 sensor - 2006/11/29 12:30
I've never had a check engine light that wasn't on. For some reason (likley the "tinkering around") Check engine is a permenent fixture. I've never really thoulght much of my street car with the light on, because the rally cars did, or would have if I didn't pop the bulb.
a few months a go Andrew scanned my street car and saw that the rear 02 sensor was bad. The car seemed fine, so I didn't bother to replace it.
I finally got around to it, but not before taking some measurments on our dyno. I'm tickled by the results.
Here is the baseline. This is my 2000 2.5 rs, with the Rallispec built motor, a bad 02, and 87 octain gas. 
|
|
|
The administrator has disabled public write access. |
Matt
Admin
Admin
| Posts: 485 | |
|
Re:02 sensor - 2006/11/29 12:33
Here is the same car with 91 Octain gas, and a bottle of octaine booster. the booster is supposed to add 5-7 to the rating
|
|
|
The administrator has disabled public write access. |
Matt
Admin
Admin
| Posts: 485 | |
|
Re:02 sensor - 2006/11/29 12:34
Now... here is the same car with all her 02 sensors working.
Astounding. First off... apparently the performance improvments with a working 02 is a compelling reason to keep them in good working order, even without concitering the emmisions ramifications.
What is the 02 sensor doing? it allows the engine to self tune it's air fuel mixture. The 02 reads the output of the engine (exhaust gas) so the computer program can adjust fuel levels to get the optimum mix. not too rich, or too lean. That makes the cleanest burning misture, and also the mixture with the most power.
Human Engine tuners do the same thing, but they arn't limited to doing what the Fuji engineers decide is the best engine setup. Manufactures tend to be interested in smooth feel and emmisions more than pure power.
Our rally cars don't compete with 02 sensors in them because antilag would destroy them very quickly. But, thay are tuned using very accurate 02 sensors. The tuner programs the ecu to add a specific amound of fuel for every rpm and manifold (intake air)pressure combination. The tuner checks the exhause gas contens with every programing change to make sure the air fuel mix is just right. Once the tuner is done, he removes the 02 sensor. You can't make many changes to a race motor before you have to reprogram the ECU.
A street car with working 02 and knock sensors can tollerate all types of engine modifications, from exhausts, to cold air intakes, to watery gas, to squierels living in the airbox. The street car won't take full advantage of these modifications, but street cars don't take full advantage of the hardare they have from the factory. But then again, it is easy to improve preformance and hurt reliability.
As a final point, 240 lb/ft Torque !!!  That's AMAZING!!! My little NA 2.5 has more engine power than a WRX.
|
|
|
The administrator has disabled public write access. |
RallyGuy24
User
Junior Fan
| Posts: 11 |  |
|
Re:02 sensor - 2006/12/11 04:23
Well I guess the $85 is worth 50hp!! Time to get a new O2 for my car!!
|
|
|
The administrator has disabled public write access. |
solbey11
User
Junior Fan
| Posts: 23 | |
|
Re:02 sensor - 2007/05/11 10:10
Wow. That's amazing. I thought the rear O2 sensor was just a catalytic converter monitoring sensor.
The front O2 sensor or A/F sensor determines how much oxygen is flowing out of the exhaust and calculates the A/F mixture off of that. The rear O2 sensor determines how much oxygen is coming out of the converter. My guess is that the ECM will adjust the A/F mixture to protect the converter from burning out if it senses the rear O2 sensor is defective.
Very interesting.
BTW, what kinda built engine do you have from Rallispec?
|
|
|
The administrator has disabled public write access. |
Matt
Admin
Admin
| Posts: 485 | |
|
Re:02 sensor - 2007/05/14 05:47
For once emisions, performance, and reliability all come in the same package. Achieving the target Air-fuel mixture does all of this.
With the right mix, all the fuel is burnt, and doesn't spew out through the cat. This is good for both the cat and the enviorment.
With the right mix you get the best acceleration. Too rich boggs down the motor, and too lean starves the motor for fuel.
Finally, the right mix will hoipefully prevent, blowby, melting, detonation, cokeing, Catalytic converter failure, and the list could go on.
You are correct that the Air fuel sensor protects the Cat, but the car really only needs one sesnor infront of the cat to do that. That way the ECM can adjust what is going in. As long as the Cat isn't junk already, what comes out should be dependant on what goes in.
The 2 O2 sensors are usually a wide band and a narrow band. I'd have to do some research to figure out exactly what the difference is.
|
|
|
The administrator has disabled public write access. |
Matt
Admin
Admin
| Posts: 485 | |
|
Re:02 sensor - 2007/05/14 06:04
I'd forgot... The engine in my RS is a turbo block (for strength) and custom built 11.5:1 compression pistons. It was still Naturaly Aspirated.
The demise of that engine(yes it died) was too much cylander clearance. I took her to Pirce Neiege for Recce and when I got back all the cylander pressure was going into the crank case and venting my oil. The pistons had machined out the space to rock, side to side. It took them 10,000 miles to do it. great for a race motor, crap for a street motor.
I'm putting that motor back together with tighter clearances and lower compression. I'd like to get 100,000 miles or more out of it, if you know what I mean.
|
|
|
The administrator has disabled public write access. |
Matt
Admin
Admin
| Posts: 485 | |
|
Re:02 sensor - 2007/10/29 14:09
My 2.5 rs street car is back toghter with the shortblock from a 97 legacy. She runs but with a serious click. It seems too much for piston slap, so the next step is to readjust the valve lash.
|
|
|
The administrator has disabled public write access. |
|
Forums
