I think I've seen it mentioned that the ECU throws the P0171/174 code if the STFTs are over 12%? Mine are well over and no codes, no lights. Could there be something else weird going on causing my car not to throw an error when it should?

Why not posting the actual numbers for stft and Ltft of yours? Total fuel trim is matter.

 

Sorry, could have sworn I'd mentioned them but obviously not. I did a cold start idle test with OBDFusion this afternoon: STFTs were 17% ~ 22% (bank 2 around 2% lower than bank 1), LTFTs stayed at 0% for the whole four minutes. I haven't had time to do the driving and warm idle tests yet.

Anyway, I raided the hardware store on my way home, knocked up a smoke tester and confirmed that I do have a vacuum leak. Two, in fact: one at the finicky little CCV hose connection that twists on and a crack in the rocker cover itself near spark plug well #1 (I saw it when I did the rocker cover gasket a few weeks ago but I didn't know enough about vacuum leaks at the time to realise it'd be a problem). I'll fix those this weekend and it should be fine. But, again, it just seems weird that to have a big vacuum leak and have the car not tell me about it. I never would have known if I hadn't checked the fuel trims on a whim. No codes, no check engine light, nothing really noticeable in terms of driveability.Maybe I'm just not familiar enough with how an E46 should drive, and once I fix the vacuum leaks it'll be a night and day difference, haha.

 

You may be seeing the difference in country coding- US and Aus emissions laws were quite different in 2001.

Also, how new are your oxygen sensors? Old ones get 'lazy'....

I've never had a big vacuum leak, so I'm not 100% sure that short term trims alone will trigger the light, even in the US.
The car looks at total deviation from baseline over time, and if it can keep the oxygen on target, then it's not emitting too much.
Whenever I've gotten the SES for trims, the long term trims were what set it.

t

 

Sorry, could have sworn I'd mentioned them but obviously not. I did a cold start idle test with OBDFusion this afternoon: STFTs were 17% ~ 22% (bank 2 around 2% lower than bank 1), LTFTs stayed at 0% for the whole four minutes. I haven't had time to do the driving and warm idle tests yet.

Did you reset the DME adaptation recently, or what is the history of engine work, car hasn't been driven many months? Give us some background.
The LTFT will change once the car is driven, unless it is so bad that the DME is always running in open loop control with no O2 sensors input being used by DME.

 

Sort the cam sensor out and go from there, that can absolutely cause vibrations at idle, it did for me when i had an issue with the intake one. Replace with genuine bmw part only, copies will not work

 

I've just plastic welded up the crack in my valve cover, I'll get it back on and secure the CCV hose on the weekend and test for vacuum leaks again. Fingers crossed it should be buttoned up tight now.

You may be seeing the difference in country coding- US and Aus emissions laws were quite different in 2001.

Also, how new are your oxygen sensors? Old ones get 'lazy'....

I've never had a big vacuum leak, so I'm not 100% sure that short term trims alone will trigger the light, even in the US.
The car looks at total deviation from baseline over time, and if it can keep the oxygen on target, then it's not emitting too much.
Whenever I've gotten the SES for trims, the long term trims were what set it.

t

That's interesting, I didn't think about regional coding differences. I know that secondary air pump on US cars works on the exhaust system, and that whole system isn't even present on my car, so thresholds for throwing errors could very well be different.

It's a sure bet that my O2 sensors are the original parts with 200,000kms and 20+ years on them, so I'll add them to the list of parts to replace.

Did you reset the DME adaptation recently, or what is the history of engine work, car hasn't been driven many months? Give us some background.
The LTFT will change once the car is driven, unless it is so bad that the DME is always running in open loop control with no O2 sensors input being used by DME.

I haven't intentionally reset anything, but I have disconnected the battery multiple times over the last couple of months (sometimes for days at a time). I've been working on getting the car shipshape again and haven't been driving it much, so I guess that might account for it having no LTFTs set?

Sort the cam sensor out and go from there, that can absolutely cause vibrations at idle, it did for me when i had an issue with the intake one. Replace with genuine bmw part only, copies will not work

Will do. I pulled the sensor out and found the tip of it covered in old oily crud, and I've just cleaned it off and reinstalled it for now. Cleared the code and it hasn't come back, so I'll keep an eye on it.

 

Little update:

• My P0369 code for the bad exhaust cam sensor came back, so I'll add one of those to my next order.
• I fixed the crack in my rocker cover (plastic welding, epoxy) and it dropped my STFTs from 22% and 19% to about 13% and 9% (bank 1/bank 2 at cold idle). Getting there.
• The other vacuum leak is at the bottom connection on the CCV hose from the rocker cover to the CCV valve itself, and unfortunately I can't fix it because it's just a rubbish part from Febi-Bilstein that simply doesn't fit properly. That brand sells junk, I swear. I'll buy another brand and sort this out, but at least I know what the problem is now.
• My LTFTs are still at 0% on both banks. Will that sort itself out as I drive the car more? I'm satisfied that I've got the car into daily driver shape now, so it's about to start doing ~350km a week.

 

I've driven about 500km (300+ miles) since my last post and my LTFTs are still 0% on both banks. They don't change at all. I haven't deliberately reset anything, thought I did unplug the MAF once to access the lower end of the CCV breather hose (not while the car was running) so I don't know if that makes a difference. Is this something I should look into?

 

Post a log showing fuel system status, O2 sensors, stft, ltft,

 

OK, I've got a couple here from within the last week. Cold start idle:

Dropbox

www.dropbox.com

And a highway cruise at 90-100km/h (couldn't get it any smoother, traffic):

Dropbox

www.dropbox.com

This warm idle log is from before I fixed the vacuum leak in the valve cover so the STFTs are a bit higher than they are now, but everything else should be relevant:

Dropbox

www.dropbox.com

 

What's the ambient temp where you are now? It's winter time, right?

 

Spring now but still on the cold side. Around 10-15 Celsius (50-60F) in the mornings, low 20s (70-80F) during the day.

 

I think I've seen it mentioned that the ECU throws the P0171/174 code if the STFTs are over 12%? Mine are well over and no codes, no lights.

These are for the USA market. Your Oz E46 uses the EU tune, so I believe that gives you till 25% before a code pops.

Thank you for the Logs.

The cold start log shows Pre-Cat O2 Bank 1 to be lazy. It could be why B1 total fuel trims are always higher than B2. Consider changing both pre-cat O2 sensors.

All the logs show that the post-cat O2 sensors are not working. Do you have catless headers with the post-cat O2's tuned out?

Everything else is looking good in the logs, including the MAF.

Yes, your LTFT's are all zeros and the STFT's are doing all of the fuel trim work. I have seen this before several times. Don't know why it happens, but the cars seem to run right.

 

Thank you for the analysis, I really appreciate it!

I'll definitely be replacing the pre-cat O2 sensors ASAP. No doubt they're the original parts and well past due at 200,000km. It looks like a much more difficult job getting them swapped on a right hand drive car (they point back towards the firewall on my car, unlike on LHDs where they point straight up, so I might have to get at them from underneath), but I'll get it done.

I don't know anything about the post-cat sensors. As far as I know the car is bone stock with no tune on it. Is this worth looking into? I've thought about updating my DME and EGS to the latest versions using these instructions on this forum, I'm guessing that would overwrite any tune that might be on there in the process? I suppose I'll also look at the wiring next time I'm in the engine bay and make sure I haven't accidentally unplugged them, haha.

As far as I can tell the car runs extremely well. Starts on the button, performance is good, fuel economy seems reasonable (8.7L/100km, or 27mpg over a week's commute). So I'm not overly worried about the fuel trim situation, it's just something I'd like to understand better.

 

You can use those instructions or INPA to read the current tune number. Then look up your car in www.RealOEM.com can see what the latest tune is for it. You can also plug in a RealOEM search for a EU car and check out their tune number.

 

You can use those instructions or INPA to read the current tune number. Then look up your car in www.RealOEM.com can see what the latest tune is for it. You can also plug in a RealOEM search for a EU car and check out their tune number.

Can you point me to where this information is on RealOEM? I'm very familiar with the site but I've only ever used it for physical part numbers, I didn't know it had this kind of info on it!

 

When one of my cats got cracked, My post cat o2 sensor went to .43 volts, with other errors of course.

 

You cannot determine if your E46 has a tune by looking at the assembly number in INPA, because it is easy to flash DME software without writing the assembly number.

 

I never would have thought my car was tuned (no mention of it from the previous owner, nothing in the service history), but now I'm interested. Is there a surefire way to find out? I wonder if my post-cat O2 Sensors not functioning and my LTFTs being static at 0% could both be related to a tune?

Just to be clear, flashing my DME with the latest official BMW version update would get rid of any aftermarket tune, right?

 

Just to be clear, flashing my DME with the latest official BMW version update would get rid of any aftermarket tune, right?

Yes, that is correct. So, if you have a tune and you flash the BMW tune, you lose the aftermarket tune.

First of all check to see if you have Cat's and that the post-cat O2's are installed.

 

Some interesting discoveries today:

- My car does have catalytic converters, and they appear to be the original, genuine BMW parts. BMW logo stamped into them, part number 7505768, 03.01 date stamp (my car was delivered March 2001). As far as I can tell, the whole exhaust system is stock. Here's the best picture I could get lying under the car (ignore the polyurethane steering giubo, obviously that's not stock ):

- My car does NOT have post-cat O2 sensors. The wiring connectors clipped to the fuel rail are there, but there's nothing plugged into them. To my eye it looks like this car never actually had them. I got under the car, took the aluminium belly pan off and could see they weren't there. I wondered if they might have been removed and the mounting holes plugged up, but when I ran my finger over the area of the exhaust where they should be I found a flattened area with no hole at all. I squeezed my phone up in there and took this picture:

I'm no BMW expert, but to me that looks like the mark they'd make at the factory to locate the hole they'd later cut to fit the threaded O2 sensor mount. I guess maybe my car was optioned without post-cat O2 sensors? The Car Details data that PASoft reads gives me:

Doing some Googling, option S199A is sometimes "Without Catalytic Converters" and sometimes "Equipment for Leaded Fuel". Neither of those seem quite right for my car (I do have cats, and my fuel filler door has a sticker saying 'Unleaded fuel only'), but obviously it's something to do with my cat/O2 sensor situation. Interestingly, none of the VIN decoders I've used show this 199 option, only PASoft (my VIN is WBABN52000JU72470, for the record).

- Apparently my DME and EGS are already up to date. Looking at my assembly numbers in the PASoft log and following Bali's instructions, I'm on the latest versions for each:
DME: MS43.0 - Assembly: 7.545.673
EGS: GS8.60.4 - Assembly: 7.546.094

I have logbook stamps from the BMW dealership in Sydney from 2001 to 2011, so I'm guessing it was just well taken care of and updated every time it went in for a service.

So, if anyone knows better then please correct me if I'm wrong, but to me it seems like my car was just optioned from the factory without post-cat O2 sensors and is basically running perfectly fine on up-to-date official DME and EGS software. Presumably my LTFTs being pinned at 0% has something to do with the cat/sensor setup and it isn't really an issue. Thanks to everyone who helped me out with this! It's been really interesting doing all this detective work, haha.

 

Great work!

I agree, your car is still standard and has been set up well. No need to do anything but enjoy the drive.