[2_Spools_919]

Hope this post helps someone out. To start, I work at a repair facility that works on BMW's. The last car I worked on this week was a stock 2016 Z4 w/ N54 and 62,0000 miles. The car came in for a check engine light and running rough on cold start. So we parked the car and let it sit to perform a cold start. On cold start the vehicle barely wanted to run, it had a very lumpy rough start. Then while connected to ISTA, and monitoring the O2 sensor status, once the O2 sensors became active the idle smoothed out but the multiplicative values were at 30% for banks 1 & 2 with fault codes 29E0 & 29E1 mixture control bank 1 & 2 too lean, So, with them both banks at 30% and almost identical, the thought process was, it has to be something that affects both banks together. So we smoke tested the intake system. We found the rear turbo inlet had a leak at the flange and the charge pipe was leaking. So naturally, we replaced the leaking turbo inlet and charge pipe. smoke tested and no leaks. Checked multiplicative values and still at 30% for both banks. Let me not forget to mention that the previous week the vehicle was towed in for a no start and we found that the low-pressure pump was only putting out 30 psi, after replacing the low-pressure pump and regulator the high-pressure pump and rail pressure sensor were replaced for rail pressure plausibility faults. So at this point, the low-pressure pump, fuel pressure regulator, high-pressure pump, charge pipe, and bank 2 turbo inlet have been replaced. No unmetered air leaks. We smoke tested the crankcase through the oil filter cap and sprayed the entire valve cover with soapy water to check for any small cracks or leaks and none were found. We measured crankcase pressure with a digital manometer and it was spot on at 17mBar. So, we disconnected the tank vent valve from the throttle and plugged the port and no change in the values they were still at 30% both banks. So, the next step was O2 sensors. We replaced all 4 O2 sensors and crossed our fingers. Nope, values still at 30%. We flashed the DME with ISTA/P and allowed vehicle to sit overnight. started it up in the morning and it ran rough again until the O2 sensors were active and the values shot up to 30%. We swapped the map sensor with a new one and still 30%. So now the last thing we thought it could be were the injectors. They were all index 12. Surely it couldn't be the coveted index 12 injectors. Luckily, this customer has a good extended warranty. The warranty company has been on the hook for all of the repairs. So, we called in the claim and they approved it. I installed 6 new fuel injectors and calibrated with ISTA. Started it up and right away the cold start was no longer lumpy and rough. While at idle without driving the multiplicative values were at 12%, a dramatic improvement. So we took her out for a good test drive. Checked the multiplicative values afterward and they were at 2.27% bank 1 and 4.97% bank 2 and the mixture faults were no longer present. I was really surprised that the injectors were the cause of the mixture faults with them being index 12. Maybe something passed through the fuel system and was restricting flow? Not sure. visually, the tips of the injectors did not appear to be full of carbon. Anyhow, this has been a long post. Hope it helps someone.

[bill3rdshift]

Great information. I'm dealing with a 29E1 as well. I'll post once I know the outcome with my car.

[aohus]

Originally Posted by bill3rdshift

Great information. I'm dealing with a 29E1 as well. I'll post once I know the outcome with my car.

what was your outcome?

[Wolf 335]

Broken down for an easier read.

Originally Posted by 2_Spools_919

Hope this post helps someone out.

To start, I work at a repair facility that works on BMW's.

The last car I worked on this week was a stock 2016 Z4 w/ N54 and 62,0000 miles.

- The car came in for a check engine light and running rough on cold start.
- So we parked the car and let it sit to perform a cold start.
- On cold start the vehicle barely wanted to run, it had a very lumpy rough start.

Then while connected to ISTA, and monitoring the O2 sensor status, once the O2 sensors became active the idle smoothed out but the multiplicative values were at 30% for banks 1 & 2 with fault codes 29E0 & 29E1 mixture control bank 1 & 2 too lean.

So, with them both banks at 30% and almost identical, the thought process was, it has to be something that affects both banks together.
- So we smoke tested the intake system. We found the rear turbo inlet had a leak at the flange and the charge pipe was leaking. So naturally, we replaced the leaking turbo inlet and charge pipe. smoke tested and no leaks.
- Checked multiplicative values and still at 30% for both banks.

Let me not forget to mention that the previous week the vehicle was towed in for a no start, and we found that the low-pressure pump was only putting out 30 psi. After replacing the low-pressure pump and regulator, the high-pressure pump and rail pressure sensor were replaced for rail pressure plausibility faults.

So at this point, the low-pressure pump, fuel pressure regulator, high-pressure pump, charge pipe, and bank 2 turbo inlet have been replaced.

No unmetered air leaks. We smoke tested the crankcase through the oil filter cap and sprayed the entire valve cover with soapy water to check for any small cracks or leaks and none were found.

We measured crankcase pressure with a digital manometer and it was spot on at 17mBar. So, we disconnected the tank vent valve from the throttle and plugged the port and no change in the values they were still at 30% both banks.

So, the next step was O2 sensors.
- We replaced all 4 O2 sensors and crossed our fingers. Nope, values still at 30%.
- We flashed the DME with ISTA/P and allowed vehicle to sit overnight. Started it up in the morning and it ran rough again until the O2 sensors were active and the values shot up to 30%.
- We swapped the map sensor with a new one and still 30%.

So now the last thing we thought it could be were the injectors.
- They were all index 12. Surely it couldn't be the coveted index 12 injectors.
Luckily, this customer has a good extended warranty. The warranty company has been on the hook for all of the repairs. So, we called in the claim and they approved it.

I installed 6 new fuel injectors and calibrated with ISTA.
Started it up and right away, the cold start was no longer lumpy and rough.
While at idle without driving the multiplicative values were at 12%, a dramatic improvement. So we took her out for a good test drive.
- Checked the multiplicative values afterward and they were at 2.27% bank 1 and 4.97% bank 2 and the mixture faults were no longer present.

I was really surprised that the injectors were the cause of the mixture faults with them being index 12.
Maybe something passed through the fuel system and was restricting flow
Not sure, but visually the tips of the injectors did not appear to be full of carbon.

Anyhow, this has been a long post. Hope it helps someone.

[Wolf 335]

Originally Posted by aohus

what was your outcome?

In his case as well as in mine, the culprit was the injector.

[aohus]

just wanted to update my results after replacing non-genuine index 5's with genuine index 11.

the mixture control error went away and have 0 codes related to it now. car drives a lot smoother and pulls better.

[cjalaff]

At first I got mixture control for bank 1. I swapped injectors 123 with 456 and then I got mixture control bank 2. I did a resistance test on the injectors and noticed injector #6 changes resistance when hot. When cool all injectors measure around 200k ohms. When hot, #6 will measure very high (500 M +) then goes out of range. As soon as it cools the resistance goes back to 200k. I swapped injectors #5 and #6 and the problem followed as expected. I am ordering a new injector and hopefully this will solve the mixture control error. + Orings and decouplers to be replaced.

[Biggsie]

Originally Posted by cjalaff

At first I got mixture control for bank 1. I swapped injectors 123 with 456 and then I got mixture control bank 2. I did a resistance test on the injectors and noticed injector #6 changes resistance when hot. When cool all injectors measure around 200k ohms. When hot, #6 will measure very high (500 M +) then goes out of range. As soon as it cools the resistance goes back to 200k. I swapped injectors #5 and #6 and the problem followed as expected. I am ordering a new injector and hopefully this will solve the mixture control error. + Orings and decouplers to be replaced.

update?

[Aode06]

Yea, you need REAL GENUINE BMW INJECTORS.
had index 12, found out they were fake.
Get new injectors and your good. BTW no one on ebay is to be trusted

[Podunk]

Originally Posted by Aode06

Yea, you need REAL GENUINE BMW INJECTORS.
had index 12, found out they were fake.
Get new injectors and your good. BTW no one on ebay is to be trusted

you know BMW doesn't manufacture their own injectors and instead farmed that process out to someplace like Pieburg/Vitesco, right?

[Aode06]

Originally Posted by Podunk

you know BMW doesn't manufacture their own injectors and instead farmed that process out to someplace like Pieburg/Vitesco, right?

Vitesco formerly Continental

[Cmanns05]

Sadly lost my engine to this. Even with genuine index 12s. I would only get the code during cold starts but Cyl6 ran lean at the wrong time and boom. On PI also, so don't expect that to save you.

This code is potentially serious. Get those injectors tested if you get these codes.

[Podunk]

Figured mine out, injectors finally started leaking, got Vitesco's, all good now and lifetime through FCP euro. also figured out my highway surging, appears it was related to the raised idle for the 335IS clutch chatter at idle to be lessened. honestly more quiet in the car at lower RPM, sounds like hell at a drivethrough though.

[Aode06]

If you get mixture control bank 1 or 2 codes, pull the 3 spark plugs for that bank and sometimes ,the spark plug that's different from the rest will show that bad injector. Index 12 do fail as well. Buy from a genuine parts supplier not eBay or Amazon. I've been scammed there a bunch.

[thormessiah]

I get this code every once a blue moon, but I am in full e85. Are all these issues happening on ethanol or just pump gas?

[PerformanceEngSolutions]

Originally Posted by thormessiah

I get this code every once a blue moon, but I am in full e85. Are all these issues happening on ethanol or just pump gas?

Whether it happens with ethanol or pump gas I think it’s still a problem? I’ve run up to E50. Haven’t run as high as E70 yet but if I saw that with any fuel type I wouldn’t feel great about it.

How’s your rail and PI pressure when that happens? (I’m assuming you have PI)

[thormessiah]

Code only appears on cold starts, and yes I’m on port injection. Car runs and pulls well, so I always assumed it was the ethanol quality

[PerformanceEngSolutions]

Originally Posted by thormessiah

Code only appears on cold starts, and yes I’m on port injection. Car runs and pulls well, so I always assumed it was the ethanol quality

If you had varying ethanol content in your tank (poor mixing) then I guess I could see it being the ethanol. Whereas you’re seeing it on cold starts only, maybe it’s the O2 sensor? I say that since O2 sensors have a heat up period before providing accurate data and maybe the heat up function on your sensor is acting up. Just a thought

[Podunk]

Originally Posted by thormessiah

I get this code every once a blue moon, but I am in full e85. Are all these issues happening on ethanol or just pump gas?

mine happened on pump gas, with only up to 10% ethanol blend.

also.. my LPFP died shortly after replacing injectors.. so i put in a Precision stage 2 non modular.. , haven't had these codes since, HOWEVER.. i have been suffering Vanos code for intake cam.. considering the 2.5K for injectors, the 400 for the LPFP only to get Vanos later, and find out my oil filter housing is trashed where the cap screws in.... i'm getting very very tired of throwing money at this car for only a few months of headache free driving..

[bill3rdshift]

Originally Posted by bill3rdshift

Great information. I'm dealing with a 29E1 as well. I'll post once I know the outcome with my car.

Sorry for the super late response, but mine was injectors. I bought index 12 injectors and that fixed my issue. Just so pricey.

[bill3rdshift]

Originally Posted by thormessiah

I get this code every once a blue moon, but I am in full e85. Are all these issues happening on ethanol or just pump gas?

Mine occurred on full E85 from gas station and I have PI as well. However, I got it resolved with new index 12's. Luckily no engine problems.

[thormessiah]

Originally Posted by bill3rdshift

Mine occurred on full E85 from gas station and I have PI as well. However, I got it resolved with new index 12's. Luckily no engine problems.

I got a Misfire in cylinder 5 a few days ago after seeing these codes pop up every once in awhile. I’ll check how the injector is looking