E92 Increased Emission and Reduced Power.

[syedhussen]

I am having the following problem with my car and I was wondering if anyone can help me?

Increased Emission (Blank 1 running too lean) After a month (Blank 1 running too rich).
Cylinder 1-4 miss fire, reduced out. (When I throttle car at higher rpm at the time of start-up. Reduced power light doesn't come on).

[M3 n X5M]

Originally Posted by syedhussen

I am having the following problem with my car and I was wondering if anyone can help me?

Increased Emission (Blank 1 running too lean) After a month (Blank 1 running too rich).
Cylinder 1-4 miss fire, reduced out. (When I throttle car at higher rpm at the time of start-up. Reduced power light doesn't come on).

I took mine in for diagnostics and recommend you do the same. This could be more than one issue.

Mine had faulty actuator on one bank, catalysts code and prior to this had a thermostat and fuel pump issue. The latter two were repaired last year in the process of sorting out emissions issues.

Other issues can be injectors or spark plugs, or even just O2 sensors.

If the car is not driving 100% then something is wrong- whether it has a code to with it or not.

[syedhussen]

@M3 n X5M

I recently changed out the spark plugs. O2 problem went away for about a week and came back. After that, I changed the air filter and after that, all the Cylinder 1-4 mire fire started.

About two weeks ago, I took my car to the BMW dealership and they asked me to replace pre/post O2 sensor, battery, and air filter.

I am sure if this will clear the problem and Can anyone tell me how to change O2 sensors in a car and where are they located at?

[kabuda]

Same issue happened two weeks ago. caused by bad o2 sensors.

[M3 n X5M]

Originally Posted by syedhussen

@M3 n X5M

I recently changed out the spark plugs. O2 problem went away for about a week and came back. After that, I changed the air filter and after that, all the Cylinder 1-4 mire fire started.

About two weeks ago, I took my car to the BMW dealership and they asked me to replace pre/post O2 sensor, battery, and air filter.

I am sure if this will clear the problem and Can anyone tell me how to change O2 sensors in a car and where are they located at?

They are beneath the car. There are 2 pre cat and 2 after. Also know as upstream and downstream.

You need to raise the car to replace them.

The easiest is to take it to an Indy shop or muffler place as they can raise the car and deal with o2 sensors when addressing catalytic converter issues or smog issues.

O2 sensors range from 140-270 for each of the two fronts and 70-260 for each in the rear. Depending on brand and store.

Look at the picture of the exhaust, where the opening of the pipe connects to the down pipe (not shown). Shortly after connecting to the down pipe the catalyst is a long piece surrounded by a small hole in front and a hole behind. Each O2 sensor goes in each of these 1/2 inch openings. Note our M3 exhaust consists of two 2.5 inch diameter pipes all the way to the muffler. The muffler is not shown.

I am on the fence to replace the o2 sensors when I replace the catalytic converters. It will cost nearly 1k or as little as 410 dollars. It all depends if I go OEM or aftermarket. The picture I attached is of the magnaflow OEM replacement system. Our BMW OEM looks almost the same but costs 3 times as much.

Labor to replace all 4 o2 sensors can run about 150.

[JsL]

Buy Bosch, which is the same as the BMW ones without the box, logo and pricetag.

BMW E9X M3 pre-cat oxygen (O2) sensor = Bosch 17039
BMW E9X M3 post-cat oxygen (O2) sensor = Bosch 16793 (limited availability - now superceded by Bosch 16421)

[syedhussen]

Thank you, everyone. I was wondering if I should replace upstream or downstream or both?

[Shredicus]

Originally Posted by syedhussen

Thank you, everyone. I was wondering if I should replace upstream or downstream or both?

Upstream are the important wideband sensors that dictate AFR changes. Secondaries are emissions related and disabled with most tunes that delete primary cats.