pugguy2001

Does the 2005 C230 need to have the o2 sensors hooked up for reasons other than emissions. I've heard alot of AMG car using straight pipes inplace of the cats and they had great results. Will the check engine light come on. While the car run properly with out both o2 sensors?

Blazinpin0i

hmmm... i know the 1st o2 sensor on the CAT if removed will throw a check engine light and error codes. I also heard that the 2nd o2 sensor is not connected to the ECU so if removed wont throw any error codes, correct me if i am wrong.

Buellwinkle

You can just use black electrical tape to cover the check engine light and your car will run on a fixed mapping that bypasses the O2 sensors but. You won't see a difference on a dyno because at WOT it bypasses the O2 sensors but you will see it in day to day driving and fuel economy but your probably prepping your car for the track so what's the difference.

In the good ole days they use MIL eliminators (do a google search) and bypass the O2 sensors but I'm sure that will work with the new 5 wire O2 sensors.

pugguy2001

I read they can use the star diagnostic tool to cancel out the check engine light for good? Does this apply to our cars.
To be honest the reason I am asking I brought my car to a race shop by me and had it dynoed. My dynos with the Kleemann mods were nice 205 h/p and 205 torque, at the wheels. I showed them a dyno before kleemann header with the boost kit and a dyno after kleemann header w/high flow cat with the boost kit and since I am a 0-60 person, they asked why did I even go this route. The Kleemann dynos showed how the whole power band shifted. which indeed it did and I know that for a fact, plus the 1/2 boost that was lost. They looked at the stock exhaust manifold and told me it was a stepped header. So he asked me, if i was willing, can he bring make my car back to the 0-60 car it was and even better. So this is why I want to know if our cars need the O2 senors. When you say fuel economy I am guessing I will loss some mpg. Anyway this whole think is just a thought. Thanks for the info

Buellwinkle

What happens when the O2 sensor is removed is the computer has a fixed set of fuel injector mappings to meter fuel that take input from other sensors like the throttle position sensor, rpm, vss to figure out the best guess fuel mix, sort of like the old days of carburators, worked but not very smart. So you take your car to altitude or drive on a hot dry day vs. a humid cool day and the mapping is the same, no way for the ECU to compensate for atmospheric conditions or compensate for a poor performing component like low fuel pressure or dirty injectors because it can't measure if the fuel mix is correct. So the downside is your car will not be as efficient as it can in drivability and fuel economy because it's guessing the fuel injector timing rather than computing it based on need. The O2 sensors are bypassed during ECU open loop mode during startup, warmup and wide open throttle because the O2 sensor is considered inaccurate during those conditions. So what do you have to lose beside fuel economy and drivability? Engine longevity is compromised because you'll run rich and leave carbon deposits or you'll run lean and overheat the cylinder heads and cause pinging. Also it's 100% illegal regardless of if your state has smog inspections, you could be fined by the EPA if someone turns you in, not likely but possible.

So what's the big deal, have the muffler shop drill in holes and weld in bungs to install the O2 sensors. They're not slowing you down.

pugguy2001

[QUOTE=So what's the big deal, have the muffler shop drill in holes and weld in bungs to install the O2 sensors. They're not slowing you down.[/QUOTE]
Ok thanks for the info. I just wanted to know alittle about the O2 sensors so when I go to he shop I can understand what they are going to saying and also I like to put in my $.02, which now alteast I now the deal about the O2 sensors. I dont want to walk into the place blind and not no what to expect.
Thanks Again
So have you been thinking about getting a header. With all of these new headers to choose from you must be tempted.

mig888

There are ways to get away with test-piping and including 02 sensors - but I wouldn't abandon them completely - they're good for something .

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