High Flow Exhuast On A MS3

[KING1307]

Hey all,
1. ive got some plans for this winter to do a high flow exhaust system for my ms3, just have a question that i havent been able to get a straight answer on, so any input from you all would be great. ive heard that if the flow on my exhaust is high enough, i wont have enough back pressure which result in problems with the turbo spooling up blah blah blah, is this true? any input appreciated.

2. also, a quick one for anyone whos using a port. is it able to keep ecl off? i know that once i throw on this exhaust im gonna get a light since i wont have the oxygen sensors in, im just wondering if the port will clear it, and keep it cleared.

3. which leads me to another question, will the ecu start to try and adjust air to fuel ratios if theres no exhaust passing by the oxygen sensors, or will it just say, oh, guess there is an oxygen sensor failure and keep with its normal ratio? and even if its tuned with the port?

thanks all, much appreciated!

[loki]

Hey all,
1. ive got some plans for this winter to do a high flow exhaust system for my ms3, just have a question that i havent been able to get a straight answer on, so any input from you all would be great. ive heard that if the flow on my exhaust is high enough, i wont have enough back pressure which result in problems with the turbo spooling up blah blah blah, is this true? any input appreciated.

2. also, a quick one for anyone whos using a port. is it able to keep ecl off? i know that once i throw on this exhaust im gonna get a light since i wont have the oxygen sensors in, im just wondering if the port will clear it, and keep it cleared.

3. which leads me to another question, will the ecu start to try and adjust air to fuel ratios if theres no exhaust passing by the oxygen sensors, or will it just say, oh, guess there is an oxygen sensor failure and keep with its normal ratio? and even if its tuned with the port?

thanks all, much appreciated!

if you don't have the oxygen sensors in then how will you know what the car is doing with respect to air/fuel?

pretty sure to keep it's "normal ratio" it relies on feedback from the sensors and adjusts the fuel trims accordingly.

In my opinion forget whether or not the AP can get rid of the CEL, removing the sensors is a recipe for disaster.

[KING1307]

if you don't have the oxygen sensors in then how will you know what the car is doing with respect to air/fuel?

pretty sure to keep it's "normal ratio" it relies on feedback from the sensors and adjusts the fuel trims accordingly.

In my opinion forget whether or not the AP can get rid of the ECL, removing the sensors is a recipe for disaster.

so then what happens when oxygen sensors break or stop working, its not like the ecu shuts down and messes up. it keeps feeding the normal, or ratio its was running before and throws on an ecl with a message saying that its not getting readings from the sensors.

[loki]

so then what happens when oxygen sensors break or stop working, its not like the ecu shuts down and messes up. it keeps feeding the normal, or ratio its was running before and throws on an ecl with a message saying that its not getting readings from the sensors.

then you go buy a new sensor

[boyracer]

then you go buy a new sensor

+1

[KING1307]

then you go buy a new sensor

very frustrating response, i was hoping to get some actual answers off this site.

[MajesticBlueNTO]

so then what happens when oxygen sensors break or stop working, its not like the ecu shuts down and messes up. it keeps feeding the normal, or ratio its was running before and throws on an ecl with a message saying that its not getting readings from the sensors.


the MS3 ecu uses the wideband o2 sensor to calculate Air Fuel Ratio and, without this feedback, how do you think the car will function properly?

bottom line, you CAN'T run the car without an oxygen sensor. the ECU doesn't "keep feeding the normal ratio it was running before it throws a CEL"... the ecu is not that stupid. it will go into limp mode and run even more pig rich to protect itself.

if the oxygen sensor breaks or stops working you go buy a new sensor...it's not a frustrating response, it's the right answer.

if you're looking for just a 'cat-back' exhaust, you don't have to worry about any oxygen sensors as there are none. if you're looking for a downpipe then every one available on the market has a bung to put your existing o2 sensor back on it.

[KING1307]

it will go into limp mode and run even more pig rich to protect itself.


that is exactly what i wanted to know, what will the ecu do without an sensor! it'll run rich, thank you. now that i know that, can you answer me this? if you are using a port and are tuned to lets say a stage 2 tune, the port must tell the ecu to feed a certain ratio correct? if it does, then if there are no sensors, will the ecu go back into this "limp mode" and feed a rich mixture or will it stay with the ratio that the stage 2 tune is supposed to be feeding?

[loki]

that is exactly what i wanted to know, what will the ecu do without an sensor! it'll run rich, thank you. now that i know that, can you answer me this? if you are using a port and are tuned to lets say a stage 2 tune, the port must tell the ecu to feed a certain ratio correct? if it does, then if there are no sensors, will the ecu go back into this "limp mode" and feed a rich mixture or will it stay with the ratio that the stage 2 tune is supposed to be feeding?

if there are no sensors, how will you even know what you are commanding the ECU will even be achieved?

Put it this way...do you know how much air you are supposed to put into your tires? So you get a pump that can pump that air in but you have nothing telling you how much air you've put in so far. how do you know when to stop? how do you know you've put in the correct amount of air? or you can just keep pumping air in until guess what happens...your tire explodes.

I wasn't trying to frustrate you with my response. All I'm trying to get at is that your car has a few ways of obtaining feedback on how its performing and one of those things happens to be your oxygen sensors. It's not as easy as saying hit this AFR and it'll do it.

[loki]

the MS3 ecu uses the wideband o2 sensor to calculate Air Fuel Ratio and, without this feedback, how do you think the car will function properly?

bottom line, you CAN'T run the car without an oxygen sensor.

here is your answer.

[MajesticBlueNTO]

that is exactly what i wanted to know, what will the ecu do without an sensor! it'll run rich, thank you. now that i know that, can you answer me this? if you are using a port and are tuned to lets say a stage 2 tune, the port must tell the ecu to feed a certain ratio correct? if it does, then if there are no sensors, will the ecu go back into this "limp mode" and feed a rich mixture or will it stay with the ratio that the stage 2 tune is supposed to be feeding?

you're either missing the point or asking the same question over and over to convince yourself that the car can run without the oxygen sensors.

bottom line... the car cannot run properly without an oxygen sensor regardless of whether you have an AccessPort or not.

[KING1307]

okay okay okay, ill except the fact. further question then. i know the reasoning for the two sensors, one after the manifold and one right after the cat. the first to determine proper ratios and second to ensure the cat is working correctly. now, question is, is the second sensor completely necessary? again, i know a ecl will come one if its removed, but its not crucial to engine operation like the first then is it?