[XC3LLR8]

Immediately after I installed the JB4 a little over a month ago I was playing with the JB4 mobile app and clicked on Read Codes and it showed a TMAP sensor fault. Car ran great and no CEL so I cleared the code. I thought I saved a screen shot, but I guess not. I think it was deleted from the Show Saved Codes at some point when I used BimmerCode or xHP Flash.

Yesterday I stopped to fill-up with E30 and clicked on Read Codes, as I occasionally do, and it showed 118001 Mixture ECU: mixture too lean. Each time I clicked on Show Saved Codes it would add a new entry, which I guess I did about 5 times (see screenshot). After that I clicked on Delete Codes and the code has never reappeared. Again, the car ran great and no CEL ever appeared. I even checked the car's display menu for errors and all was good.

Does this mean the JB4 is a lot more sensitive than the ECU to recording/storing codes? I have no idea if any of this is related to the JB4, but I do know I'd never know these codes appeared if not for the JB4's mobile app.

[PNTDG42]

Its getting those codes from the DME. Both codes make sense. JB4 interferes with the TMAP as part of its technique for manipulating more boost. Mixture too lean makes sense for multiple reasons. If you just switched from gasoline to a E30 blend, since the car is not flex fuel or tuned for that blend, it will cause the engine to run lean until the fuel trims catch up. Also since the JB4 cranks boost without tuning, it wouldn't be any surprise to get the lean mixture code even on standard pump gasoline.

Either these codes are allowed without immediately displaying the CEL, or JB4 is immediately clearing them from the DME to hide the CEL but storing them for your viewing later. If you email them I am sure they can tell you which it is. Or if you plug in a different OBD reader, you will be able to tell which it is, by seeing if the codes are showing or already cleared.

[XC3LLR8]

Originally Posted by PNTDG42

Its getting those codes from the DME. Both codes make sense. JB4 interferes with the TMAP as part of its technique for manipulating more boost. Mixture too lean makes sense for multiple reasons. If you just switched from gasoline to a E30 blend, since the car is not flex fuel or tuned for that blend, it will cause the engine to run lean until the fuel trims catch up. Also since the JB4 cranks boost without tuning, it wouldn't be any surprise to get the lean mixture code even on standard pump gasoline.

Either these codes are allowed without immediately displaying the CEL, or JB4 is immediately clearing them from the DME to hide the CEL but storing them for your viewing later. If you email them I am sure they can tell you which it is. Or if you plug in a different OBD reader, you will be able to tell which it is, by seeing if the codes are showing or already cleared.

That makes sense. The TMAP code never reappeared after the first time, and the Mixture Too Lean only appeared after I had been running E30 for awhile, then ran a half tank of only 93, then went back to E30 which had been in the system for a 1/2 tank's time. And as of now the code hasn't reappeared.