I3 REX 2015 125001,125002,125003 Misfire

[rickcvk]

I thought I should share my experience with this problem so far.
I got the drivetrain error message come up on the highway, did not get any other warnings before.

I am following the ISTA test plan for the error.

Here is what I have done so far.
1- Replaced Fuel Pump Relay
2- Spark Plugs
3- Tested coils for spark.
4- Checked Fuel Pressure (75 PSI) (No sensor or port on car for this, you need external pressure gauge a bit of a mess)
5- Tested fuel injectors by applying 12V each (this may not be a conclusive test)
6- Tested MAP sensor for both pressure and temperature
7- Smoke test to see if any leaks
8- Next in line is to replace the crankshaft sensor per ISTA

Currently, when I try to start the engine using emission start procedure, it starts ok and keeps the RPM at 2100RPM for total of 20 seconds and quits throwing the error codes at the real engine start which is after the 5-10 seconds. Since it is a distinct and quick error, I tend to believe it might be a sensor like crankshaft sensor that responds quickly.
The starter runs for a very long time in these engines unlike a regular engine start.
The oxygen sensor AIR/FUEL ratio goes up to 1.99 (MAX), telling me that it is super lean condition.
I monitor these using the ECU functions for RDME in ISTA.

https://youtube.com/shorts/P_75RQCQFWc?feature=share

 

[rickcvk]

I just changed the crankshaft sensor and it still has the same codes.

 

[spartacus68]

The fuel pump relay is a likely candidate, but as you’ve replaced it, along with the spark plugs, I’d take a closer look at Lambda oxygen sensor. Had similar issue with mine and BMW will literally replacing parts left, right and centre. They changed out this sensor and even the fuel tank first. Then finally the fuel pump relay.

Part for mine was 11788604930

I should say it wasn’t a misfire, rather CEL error, to the point the engine wouldn’t engage. It would also be worth investigating the HV cable points. These cars do suffer from corrosion and moisture on these points. Switch off under the frunk before releasing, cleaning and reattaching cable points.

 

[rickcvk]

I just did the compression test, they are 241 and 242 PSI.
Also, I attached injection test bulbs on the outputs, it only lights up for 2 seconds and quits while the engine is still cranking.
It seems to just not like something before engine has a chance to start up.

 

[rickcvk]

Hi spartacus68-
That number is for after cat oxygen sensor. I did not check that one yet. Do you think your problem was solved with this sensor in the end?

 

[rickcvk]

I just tested the after cat oxygen sensor using ISTA, RDME diagnosis page. It always reads 1.28V. It is a four wire sensor so it is probably not wideband, so it may need to completely heat up before reading anything good.
It would be really nice to have a good working RDME test values on this forums so we know what we should expect for a normal operation.
I will surely post them once I can run mine.

 

[rickcvk]

Injection pattern does not look great, I will try to clean first and possibly replace them.

 

[rickcvk]

I disconnected the connector to the throttle body and tried to start the engine. And it started and kept running without stopping this time. The AFR went down to around 1 instead of 1.99. It sounds a little rough but not too bad, expected. When I manually close the throttle a little it actually sounds normal and pressure reading gets in the range, 57Kpa.
It may be the throttle body ?
Also, I only have the throttle body communication errors and no misfire errors.

I can probably say what it is not,
1- Injectors
2- Oxygen sensors
3- Coils
4- Spark Plugs
5- Fuel Tank related issues
6- Camshaft Sensor
7- Crankshaft Sensor

It still can be
1- Vacuum leak
2- Clogged intake return lines, (turbulence lines)
3- Throttle body

 

[agzand]

There was a discussion about this TSB on facebook group today:

https://static.nhtsa.gov/odi/tsbs/...uMDFTsMLIRlAyLy0UvGwF3FMlb2uNg74M8edmEl5d8LCo

Not sure if it is useful for your car. The solution costs $16, so worth trying.

Some claim this is the same as Techron fuel additive that you can buy for $8.

My understanding is that engine control module cannot compensate for garbage winter fuel and altitude.

P.S. I see online part stores offer the BMW part for around $9, so that would be my choice:

https://www.bmwoffairfaxparts.com/oem-parts/bmw-i3-rex-fuel-additive-246060-831530-83195a2a4b0

 

[spartacus68]

Hi spartacus68-
That number is for after cat oxygen sensor. I did not check that one yet. Do you think your problem was solved with this sensor in the end?

Apologies for delay in responding. They swapped it out, but it was the fuel pump relay that eventually sorted it. Just to reiterate, it wasn’t a misfire, but engine refusing to fire up.

 

[WasylO]

Thank you for the answer. I was just looking for information and came across your answer.

 

[spartacus68]

Any update on the fix for this?

 

[agzand]

Anyone who has these error codes should try this fix first:

https://static.nhtsa.gov/odi/tsbs/2...uMDFTsMLIRlAyLy0UvGwF3FMlb2uNg74M8edmEl5d8LCo

You can buy the part for less than $10.

If that didn't work try fuel pump relay next.

 

[HelmutK]

Hello from Germany. May I ask if the Problem is solved?

 

[Candece]

I tried adding the fuel additive and it seems to have worked. It is may and I live in Chicago. I topped off my gas with premium gas and that night I tried using it again and hot misfire codes. The temperature has dropped from 70 to 50, is this the issue, will it never work in cold again?

 

[agzand]

I tried adding the fuel additive and it seems to have worked. It is may and I live in Chicago. I topped off my gas with premium gas and that night I tried using it again and hot misfire codes. The temperature has dropped from 70 to 50, is this the issue, will it never work in cold again?

There could be other issues, but you can try fuel additive and mid grade gas. Let it run for an extended time if it is working.

 

[Candece]

Thanks, tried that, didn't resolve issues. I'm going to try a fuse for fuel, then spark plugs. I'm at 78k miles so maybe it needs that

 

[Candece]

I just changed the fuel pump relay and the engine is now running. Put the scanner on and cleared all codes. I will be getting an oil change on Monday and someone will be changing my spark plugs just in case. I need to take this on a 4 hour trip so I am glad it is working.