DME Issues?

[WolfeBMW135iM]

Hello all. I have a question about the DME. I recently upgraded to the BMS intake manifold, oil thermostat, and custom oil cooler. All that went great for the most part (oil cooler upgrade was a pita I’ll share pictures of install in the best practices post). However, during the reinstall of the DME connectors I must have swapped them and tried starting the car to no luck. I figured that out and the car starts and drives but I have a flurry of errors and limp mode. I’ve scanned the car and get various codes. My best guess is that when the connectors were switched it probably could have fried something? Also my JB4 tune doesn’t load anymore. So my question is where to start digging and what’s the best approach? Could I simply take it out and send it to somewhere to get it tested and reflashed to stock? Side note I don’t know why but the factory way it was made it extremely difficult to connect not sure if the new manifold has it slightly in a different position. I had to unbolt the harness bracket to get it to fit. Any suggestions or thoughts would be greatly appreciated.

[ShocknAwe]

Completely return to stock, power cycle via battery, clear codes and see if you can start. By this I mean Checking EVERY SINGLE PIN in your DME box and make sure they're all straight. Make sure the scissor clamps aren't broken. And tighten down totally. Making sure the terminals fully seat. Remove all adapters and jumpers and power taps. Clean all connectors and clean them again. Make sure battery is fully charged in interim. Do all this with the battery out of the car.

If problem persists with BMS products installed only, call them or get rid of the JB4.

I prefer flash only tuning in 2025. It's superior. JB4 is a nice tool in select circumstances, or 2015.

[Rekraps]

Originally Posted by ShocknAwe

Completely return to stock, power cycle via battery, clear codes and see if you can start. By this I mean Checking EVERY SINGLE PIN in your DME box and make sure they're all straight. Make sure the scissor clamps aren't broken. And tighten down totally. Making sure the terminals fully seat. Remove all adapters and jumpers and power taps. Clean all connectors and clean them again. Make sure battery is fully charged in interim. Do all this with the battery out of the car.

If problem persists with BMS products installed only, call them or get rid of the JB4.

I prefer flash only tuning in 2025. It's superior. JB4 is a nice tool in select circumstances, or 2015.

Great advice. I might add, even though he seems to be a confident DIY person, to just have the dealer reset the DME to stock. Then he can redo the tune afterwards. All these electronics are excellent... until they aren't.

[WolfeBMW135iM]

ShocknAwe thanks. Just so I make sure I understand, disconnect the battery and charge, then disconnect the JB4 and reconnect the factory harness dongles. Once all are cleaned and reconnected check all DME connectors (none of the scissor clamps are broken) and ensure all connections are tight. Once battery is at full charge, clear all codes, then start the car. If the problem persists, I’d assume the DME would need to be reflashed correct?

Also, in the interim is it okay to drive the car around town like this?


Additional information, I get random failures of items such as cruise control or DSC, etc…

[WolfeBMW135iM]

Originally Posted by Rekraps

Great advice. I might add, even though he seems to be a confident DIY person, to just have the dealer reset the DME to stock. Then he can redo the tune afterwards. All these electronics are excellent... until they aren't.

I might do this if I don’t have the time, back before the toddler I’d have all the time to do this but now lol 😂 thanks!

[ShocknAwe]

Originally Posted by WolfeBMW135iM

ShocknAwe thanks. Just so I make sure I understand, disconnect the battery and charge, then disconnect the JB4 and reconnect the factory harness dongles. Once all are cleaned and reconnected check all DME connectors (none of the scissor clamps are broken) and ensure all connections are tight. Once battery is at full charge, clear all codes, then start the car. If the problem persists, I’d assume the DME would need to be reflashed correct?

Also, in the interim is it okay to drive the car around town like this?


Additional information, I get random failures of items such as cruise control or DSC, etc…

Effectively. Check your fuses too and replace any suspect items. If it still has problems it could be a fried mosfet or issue with DME itself.

Baby steps. You should be ok.

[WolfeBMW135iM]

Update: So I did exactly as you suggested and once I fired her back up ran perfectly normal! So somehow maybe when I reversed the connectors I messed up the JB4 and not the DME. I’m in contact with BM sports to see what their thoughts on what happened. Thanks again for the help and suggestions!

[ShocknAwe]

Originally Posted by WolfeBMW135iM

Update: So I did exactly as you suggested and once I fired her back up ran perfectly normal! So somehow maybe when I reversed the connectors I messed up the JB4 and not the DME. I’m in contact with BM sports to see what their thoughts on what happened. Thanks again for the help and suggestions!

Glad it worked for you!