Too rich condition bank 1&2 on M54

[itsbrokeagain]

So I've been getting this code on and off during the colder months since I bought my X5. I figured I'd post it here because the M54 is identical to us E39 owners and most X5 forums are dead.

Contrary to everyone getting lean codes, I get E3 and E4 codes "Bank 1 and Bank 2 mixture too rich" codes. ISTA gives the same codes, I think a P code is 1072 or something. Not much info out on this as it seems to be very rare or the people that do get it, the threads go silent without any kind of fix. Truck has 165k on it.

The troubleshooting I've done so far:

-AMM reads 12-13kg/s at idle (verified that across TIS and several others)
-Fuel Pump and Filter are new (50k miles or so)
-no vacuum leaks (M56 valve cover done and CCV deleted)
-Plugs have 50k on them
-DISA is original (doesn't rattle but replacing Monday as piece of mind)
-5 out of 6 coils are original
-Primary 02s are two months old (Bosch units)
-SAP works but is a little weak in the colder months (planning to replace or delete)
-Secondary Air valve was pulled and inspected, nothing outside the ordinary soot buildup, cleaned anyway. This one is a one way check valve that I guess the pump 'blows' open, as it doesn't have the vacuum line attached to it like the M54B25s and M52TUs do. Do they ever get stuck closed?

Every now and again when I pull these codes I'll get a random #3 misfire as well. Me thinks the coils are prolly well overdue for replacement.

My question is, has anyone ever experienced leaky fuel injectors on an M52/M54? My sources have all said they've never seen it ever, so I'm guessing the chances are pretty low. I'll get an odd stumble warming up in the morning like once every 5-6 weeks for 1 second.

DISA and coils will be getting done Monday to start, and I'll report back with results then.

[edjack]

Does the engine heat up fully? If not, the DME will order more fuel.

The SAP only runs for a minute or two at cold start.

Might be a faulty dual temp sensor.

A bottle of Techron might be worth a shot.

[itsbrokeagain]

Does the engine heat up fully? If not, the DME will order more fuel.

The SAP only runs for a minute or two at cold start.

Might be a faulty dual temp sensor.

A bottle of Techron might be worth a shot.

Thermostat prolly has 50k on it as well. Always gets hot. Due to the large amount of coolant it takes (almost 2 gallons) and the little 3.0L takes a while to reach full heat if I'm bleeding it off good during the cold months. It heats up much quicker when I drive it without the heat on at first.

Watching the cluster it will hover between 90-93C while cruising, so I think the thermostat is good.

[Poolman]

Like that faulty duel temp sensor thought. They can fail to do the job correctly and will fail incrementally. Cheap part and can be a pain to install, if ya don't know the trick.

[edjack]

Must be an elaborate trick, considering where that bugger is located!

Glad I have a V-8; the sensor is out in front of God and everyone.

[itsbrokeagain]

Like that faulty duel temp sensor thought. They can fail to do the job correctly and will fail incrementally. Cheap part and can be a pain to install, if ya don't know the trick.

Down underneath the Intake manifold I'm assuming?

[geargrinder]

Toss a fuel pressure gauge on it maybe IBA? If the FPR is over-pressuring you'd get rich.

I like the other ideas too (confirming temp sensor, coils...)

[itsbrokeagain]

Toss a fuel pressure gauge on it maybe IBA? If the FPR is over-pressuring you'd get rich.

I like the other ideas too (confirming temp sensor, coils...)

Yeah I have a snap-on gauge, will put that on when I get to the shop.

It's been two years since I did the fuel filter in the truck, I have to drop the panel and have a look. I've seen the regulator fail and fill up with gas, and get sucked in through the vacuum line.

And seems the disa valve is on hold, only genuine available at the moment and I'm not gonna work out $300+ for one when my reliable aftermarket source has them for $200 all day.

[Poolman]

The sensor is located at the very back of the intake manifold , at the top of the head. A crows foot wrench is what I used to remove it. Tried like crazy to remove the electrical connector from it but couldn';t
Might be able to loosen it and spin it out with the connector hooked to it, but I grabbed a pair of pliers and grabbed it under the connector and then broke it from the sensor , that worked great for me

[BMW540san]

Thermostat prolly has 50k on it as well. Always gets hot. Due to the large amount of coolant it takes (almost 2 gallons) and the little 3.0L takes a while to reach full heat if I'm bleeding it off good during the cold months. It heats up much quicker when I drive it without the heat on at first.

Watching the cluster it will hover between 90-93C while cruising, so I think the thermostat is good.

Isn't the t-stat opening temp 96C? That would indicate it's opening early and maybe causing your issue? Yes, it's DME controlled too but DME only lowers the temp under certain condition.

[pshovest]

.........I get E3 and E4 codes "Bank 1 and Bank 2 mixture too rich" codes..........

Are you're reading these E3/E4 codes with INPA? It's confusing, but these codes can indicate a lean condition.
It's is a quirk of the BMW tools that they report errors from the DME's perspective. The DME is adding fuel above what is mapped in the DME based on MAF values, therefore the DME believes the car is running rich.

The reality is the vacuum leaks cause MAF to under report airflow and O2 sensors bring things back to stoichiometric by adding fuel, via the fuel trims.

You can check this by looking at the fuel trims, INPA or any OBD scanner with live data will let you see them. If they are positive you've got a lean condition due to vacuum leak(s), bad MAF, or low fuel pressure. If they're negative, it is indeed too rich.

Leaky fuel injectors usually show up as rough running after cold start or extended crank times on a hot start.

[itsbrokeagain]

Isn't the t-stat opening temp 96C? That would indicate it's opening early and maybe causing your issue? Yes, it's DME controlled too but DME only lowers the temp under certain condition.

I checked it today while cruising home and it was sitting between 93-96. I was using some of the heat and had the windows cracked. Around town it sits at 96 and doesn't budge.

It's definitely a rich condition, im well familiar with the lean codes lol. I'll have to grab my laptop and fire up INPA to check the trims as ISTA is godawful slow in doing it's thing. I'm using an autel maxidas at the moment Cuse it's way quicker.

[geargrinder]

So the t-stat and gauge-half of the sensor seem to be working.

But remember the dual temp sensor has 2 halves (hence the dual, derp derp )

Supposedly with the right magic button presses and key positions you can make the cluster test display show one or the other... I've never messed with that cuz I generally find the cluster test stuff to be tedious and annoying and I just plug a PC into the car instead, but if you can compare the 2 sensors you might find the one the DME uses is out of whack... even if the cluster display one is OK...

[itsbrokeagain]

So the t-stat and gauge-half of the sensor seem to be working.

But remember the dual temp sensor has 2 halves (hence the dual, derp derp )

Supposedly with the right magic button presses and key positions you can make the cluster test display show one or the other... I've never messed with that cuz I generally find the cluster test stuff to be tedious and annoying and I just plug a PC into the car instead, but if you can compare the 2 sensors you might find the one the DME uses is out of whack... even if the cluster display one is OK...

Interesting. I'll have to dig up that thread that explains the test fictions and have a morning read. As for now still waiting for the DISA to show up, I have new tie rods and 4 new tires to put on as well which will prolly get done before this darn valve appears

[jclausen]

I would look at live data from the pre cat oxygen sensors

[16valex]

I had the same fault codes with my M54 but mine is supercharged. Cleaned the MAF did the trick for me, but again S/C tends to have more oil residue than none S/C.

[kouks]

Ive had this issue with my M50 in the e34 and still cannot find why it runs rich, The engine is a complete top end rebuild and nearly everything is new. I know the M54 has more stuff on it, but if you figure it out I'd like to know, the M50 is a close relative.

[geargrinder]

Interesting. I'll have to dig up that thread that explains the test fictions and have a morning read. As for now still waiting for the DISA to show up, I have new tie rods and 4 new tires to put on as well which will prolly get done before this darn valve appears

IBA - have you had a chance to connect INPA and check live trims and O2 and engine temp that way? Curious to hear results...

Agree ISTA is a PITA... avoid unless absolutely required...

[Poolman]

When I swapped out the dual temp sensor, I broke apart the sensor and inspected it. The sensor was oem and been on the engine for over 150,000 miles. There were small particles of crystallized coolant inside the sensor. This was a sure indication that the sensor had been contaminated from the coolant. What that might have caused , concerning problems with the sensor, I have no clue. After replacement,I noticed a significant increase in my fuel mileage. Might help , might not in your case, but 2 cents issued

[jclausen]

Just had a e46 rich mixture adaptatios both banks precat 02 sensor stick at 1.5 volts and not cycling at all. Replace them fixed

[itsbrokeagain]

IBA - have you had a chance to connect INPA and check live trims and O2 and engine temp that way? Curious to hear results...

Agree ISTA is a PITA... avoid unless absolutely required...

Haven't had any chance of getting to the shop. Have a little one on the way in December and last Saturday was the baby shower, finally got my check and had to go pick up my wagon (got $4600 woohoo!) And then nothing but burnouts and power outages in the Bronx so worked a few doubles. Im gonna try to make some time after the gym in the AM tomorrow to run off to the shop and do some logs and see what she comes up with.

- - - Updated - - -

When I swapped out the dual temp sensor, I broke apart the sensor and inspected it. The sensor was oem and been on the engine for over 150,000 miles. There were small particles of crystallized coolant inside the sensor. This was a sure indication that the sensor had been contaminated from the coolant. What that might have caused , concerning problems with the sensor, I have no clue. After replacement,I noticed a significant increase in my fuel mileage. Might help , might not in your case, but 2 cents issued

You know what, my fuel mileage seems to be lower on average cruising about 60...gauge reads barely 20 yet people are saying they are 23+ all day. Another thing to look at.

Pre cat 02s are new Bosch, but who knows one could've been defective out the box. I had this code come up last year when it was getting cold and I was on old 02s so that's why I was ruling them out.

[itsbrokeagain]

Laptop was being a PITA yesterday so back to the Autel. Cleared faults (had misfire for 1/3/4 as well), reset adaptations. Watched the 02s cycle, coolant temps and LTFT and STFTs for the 40 min drive in. LTFTs moved up evenly, sat around .08/.09 ms by the time I got home in the evening.

STFTs were very different. At first they didn't move. Then they slowly climbed positive on the drive in (coolant temps at a steady 93C), up to 4.3/5.6%. From doing some reading the SES light will come on at +/- 8%.

Left it at that. At 11pm I left work, pulled up the live data, started the car cold. No stumble this time, 02s stayed lean while the air-pump ran (as they should, so I know the pump/air valve is still working), then immediatley went to cycling as the car warmed up. LTFTs remained more or less the same, but by the time I got home my STFTs had gone from spiking to 5.1/6.2%, to 0.5%/2.1%.

The light isn't on yet, so I will continue data logging it this morning to see if it continues to trim into the negatives, would indeed indicate it's trying to pull fuel to straighten things out. Doing an oil change later this afternoon for a big trip tomorrow (heading 4 hours west to look at an X5D), so I'll try cleaning the MAF as well.

For poops and giggles I ordered 2 new coils, going to stick them all in bank 1 along with the coil I first replaced, so if I do get the SES light again and I get any misfire codes and they only say 4/5/6 of some variation, I know the coils are contributing to this issue.

[geargrinder]

You say negative but you didn't write "-" on the numbers... I'm assuming those ARE all negative numbers?

I'm real skeptical of the coils all crapping at once, that's uncommon. Much more likely that another issue is causing the rich mix to misfire.

Did you ever get fuel pressure checked?

[itsbrokeagain]

You say negative but you didn't write "-" on the numbers... I'm assuming those ARE all negative numbers?

I'm real skeptical of the coils all crapping at once, that's uncommon. Much more likely that another issue is causing the rich mix to misfire.

Did you ever get fuel pressure checked?

Will do that as well once I reach the shop.

I didn't write - as these trims were reading positive. The Autel isn't exactly cheap (new was 799-1000 bucks with all the goodies) so I would assume it has the capability of telling me positive or negative. I'll know for sure if it does go negative this morning when I check it again.

[geargrinder]

Ok errrrr then I'm at a vast loss for why are you saying "negative" verbally? Theres no doubt the Autel should indicate sign.

That data for sure says positive fuel trims to me and therefore suggests vac leaks and therefore consistent entirely with the misfires. And a much more common problem.

I know you get a periodic "rich" error but your trims ain't for rich problems, brothah.

Scenario hypothesis: intermittent vac leak (some fault that opens/closes up w temp - seen it plennytimes), comes and goes, when it is occurring, car trims super rich (and as you properly note those trims are fairly big). Sometimes the super rich trims are set and then the leak happens to close up, causing a sudden rich condition, bam rich code.