Coolrex...errr, CoolBimmer, errr...Delette goddamn you google not have a tommy boy poster, but... WHAT'D YOU DO!?!?!?
Apparently the code is for the MAF but Brett says Subaru's will throw a MAF code for a bad o2? That true? I can definately see one (or both) of the two pre cat o2's dying on me. Good thing I have 2 post cat o2's and can use those to test and see if I do indeed have a bad o2 sensor. But I'd figure I would be throwing some o2 related codes.
I did header install. But the MAF is on the other side of engine and was never touched or anything hence why I'm confused.
Here's basically what is going on..... Okay I have some issues after a header install. I was expecting some o2 issues but it doesn't seem to be so. If you crank car up it idles just fine. But if you go to drive it, it severely limps and the SES light comes on. I use Carsoft 6.5 to scan my codes. According to Carsoft I'm throwing HFM sensor. What in the world? The MAF? So I take it off and clean it and try again. Same thing. If I drive the car it'll run very rough and idle rough. Turn car off and the SES light is gone. Idles just fine until you drive and the cycle starts again. Now I haven't even touched that dang sensor or the intake. Weird. Any ideas people? Does this sound like the MAF is indeed bad? How can I test it without spending a ton of money on a sensor I may not need?
Hmm, sounds like a BMW. edit -- found this: http://www.euroteknik.com/forum/bmw...unning-really-rough-after-header-install.html
umm, something's not kosher the maf should scale based on the o2 sensors, meaning the o2 sensors aren't reading right and maf can't scale. It's a loop and something in there isn't reading correctly brett, justin and I are debating this now...we'll forward along our drunk inputs...
why would you have an o2 issue from a header install? thought right now is you may have shorted, grounded or melted a wire? need more info
The 4 o2's are in the headers themselves on the M3. 2 precat and 2 post cat. The post cats purely monitor cat efficiency and the M3 has to drive a while to pop that CEL. I'm not using the post cat sensors but they are plugged in for the heater circuit. And the cats are in the headers too hence why I am doing a header install (catless FTW).
My guess is one of the sensors was broken since you're confirming that the banks aren't swapped. And if the physical sensor isn't broken, then a wire is borked in there somewhere. You could always take a multimeter to insure you've got (a) a circuit and (b) the correct voltage.
Yeah. I'll do a live data test tomorrow and see if I can see obvious incorrect voltage outputs from the o2's. Any idea if a broke o2 will just read a constant value or what?
i would think if it wasn't shorted (or melted together) it wouldn't read anything at all. You're talking about a sensor with an open end, therefore no input. let us knwo what the test says
I'm just trying to recall what I remember seeing the last time I looked at a live datafeed from my ECU...and I vaguely remember seeing the sensors reporting a voltage back to the ECU. I can only assume the BMW ecu is at least on par with my Subaru's. And if memory serves, the error codes specific for fault sensors will show a something like circuit problem blah blah blah.
Does it have some sort of exhaust recirculation valve? I've seen one of those get stuck open due to a carbon deposite on a "2.5RS" and cause similar issues
Coolbimmer borked his car....that what happened. Researching I found a post that the tags on the sensor don't mean jack. Just because it says 1 on the sensor doesn't mean it goes into bank 1. So I'm gonna swap the o2's around and see what happens.
could it be the equivalent of going catless on a subaru and needing the little 02 sensor adapter to fool the cel?
In the Subaru you still run just fine with that catalyst inefficiency CEL. In my case I'm in limp mode. Latest reports.......another M3 owner said his sensors yellow tags were 'mislabeled'. And he was running just like mine....perfect idle until you drive it. Swap his sensor and voila fixed. So I have a starting point tonight and thankfully it's only about 20 mins worth of work to swap and test.
You can't. Have to drop manifold and then pull o2's on stock. If the o2's were dead I should be throwing multiple o2 codes. Note I said 'should'. I will swap o2's and see how it goes.
is the subaru ecu even close to the bmw ecu? Dana could be right in the fact that the bmw limps when it notices something wrong to prevent further damage. I'm still confused on why the o2s would suddenly just stop working if you didn't do anything with them
BMW DME is way smarter and advanced than the Subaru ECU. I think I have the o2's swapped. My car has 4 o2 sensors. 2 pre cats and 2 post cats. Car is a true dual exhaust all the way to the muffler so it has sensors in each pipe. My headers are two piece just like factory. If you put bank 1 sensor (front header) in bank 2 (rear header) and likewise the other way then bank 1 is reading for bank 2 and the values aren't right in conjunction with the engine pulses. Hence limp mode. Swapping sensors when I get home from work tonight.
4 O2's holy hell batman. and i was catching hell just getting the ONE out of the bike. keep us posted
Least you can interchange them all if you splice them. And least they are all narrow band so they $60-70 each instead of the absurd $180 the Subaru front o2 was.
From what Cicio and Doug have told me....the DME is vastly enhanced over the Subaru. More bits and many many many more tables. I think it takes like 45 minutes just to read and write the mapping to a format for Doug to read it and alter it.
this.. after all the germans invented the term 'ANGST'.... ETA. i had an M3 for a while. bought new. car had me worried till the day i sold it. what worried me the most was that i wouldnt sell it before the warranty expired. nice cars, nice interiors. but can be expensive to maintain. the germans seem to get a bit carried away with the electronics in their cars too. and sometimes they have issues.
Mercedes is a perfect example of electronics gone awry. I think half the lots were full of loaners at one time.