Check engine light

[rwh11385]

Cruising around, usually on the interstate and maintaining the same speed/RPM for a moment, the CEL will come on, but when I brake and/or accelerat, it goes out.

Anyone know what is up?

[MarkD]

Re: Check engine light while at a steady RPM

Cruising around, usually on the interstate and maintaining the same speed/RPM for a moment, the CEL will come on, but when I brake and/or accelerat, it goes out.

Anyone know what is up?

Mosy likely your O2 sensor or AFM. When did this start?

Try installing your stock chip and see what happens.

MarkD

[rwh11385]

I was planning on replacing the O2 sensor soon (perhaps today, but we'll see.....loooong day @ work and dinner w/ gf)

If that doesn't solve it, it may be the AFM likely, as it's not the most beautifully swapped M30 AFM project.

thanks

[Mystikal]

Do the test code check, or just take it to your mechanic and pay him to twist the ignition key. ;)

http://www.unofficialbmw.com/repair_faqs/motronic.html

[rwh11385]

Never had a time I needed to learn that before, thanks.

1222, what i suspected, but wasn't sure of.

definately doing that tommorrow - O2

[rwh11385]

Replaced it, check light still on, but running better and more efficent.

Need to disconnect battery to lose CEL?

thanks Jay & Mark D

[Mystikal]

It usually goes away by itself, but a full reset couldn't hurt.

[randywalters]

Replaced it, check light still on, but running better and more efficent.

That's because the 1222 code does NOT mean the oxygen sensor is bad. That would be 1221. 1222 means there's some sort of air leak or vacuum leak in the intake system. What made you think 1222 was the oxygen sensor?

[rwh11385]

Replaced it, check light still on, but running better and more efficent.

That's because the 1222 code does NOT mean the oxygen sensor is bad. That would be 1221. 1222 means there's some sort of air leak or vacuum leak in the intake system. What made you think 1222 was the oxygen sensor?

Because I incorrectly thought 1222 was the O2. Since I *thought* my O2 was cooked, and I *thought* 1222 referred to the O2.....I assumed it was all good.

1222 Oxygen Sensor Lean/Rich Detect (primary) If the signal from the O2 sensor indicates a very lean or very rich mixture for more than 10 seconds, then the computer generates this code. It could mean a faulty O2 sensor, or a problem with another component.

The confusion messed someone else up as well:

http://www.unofficialbmw.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=2&t=010413

After replacing the o2 sensor the problem was still there. This is the "official" definition of the code...

This code is stored when the DME detects excessive deviations in the air-fuel mixture (too rich or to lean) for longer than 10 seconds. Possible causes: Fuel tank ran empty, Incorrect fuel pressure, Injector valve defective or cooked, Engine temperature sensor defective, Secondary air leak, Fuel evaporation control system defective, Air flow meter defective, and/or the combustion is being disturbed by mechanical failure (Spark plug, compression, intake/exhaust valves, etc.)

I wish I could have found the definition of Lamba Control 1 earlier.

Now not wanting to run while idle and only WOT really works right. Going to have to try to cure problem with "1215" or just wait until Friday when I can swap the stock AFM back in.

Oh well. Jay, you win. Until I get the M30 AFM repaired, or replaced......we are pretty much on a level playing field.

[e30evolution]

the o2 sensor code does not always mean the sensor itself is bad...
the PCM takes info from the o2 sensor and adjusted the duration of the fuel injectors to either lean or enrich the mixture.....
watch the o2 sensor pattern with a DSO it should look like a failry steady sin wave between .1v and .9v

put the stock chip back in

[rwh11385]

I don't have the stocker on me.
I don't have the spare M20 AFM on me. (which will 95% sure solve the problem for now)

so I will see if anything is visually messed up with the AFM or connections there.

I'm going to have to drive 60 miles with a CEL.

[e30evolution]

if its an o2 code its fine (to a point)... you just arent very fuel eficent

get your hands on an osciliscope and watch what the sensor is doing before you replace it

[rwh11385]

No, after replacing the O2, I am getting a clear "1215" code.

Air Mass/Volume Sensor 1215

After finishing talking to my gf, and getting some other shit done, I'm going to mess with it and see if I can somehow fix it.

But I can just swap the M30 AFM which is ghetto now for some reason with my good spare M20 one and it *should* be all good.

[Mystikal]

Ha! I knew I was right. Expect better acceleration.

[rwh11385]

Oh, well. Started the car up today to drive across campus. The CEL was on solid.....then went away and it ran fine.

A little rough idle, but getting better, although it drives pretty well. No CEL light.