Originally Posted by Terry @ BMS

The JBD is a simple PnP tune that alters the fuel rail pressure. There are almost 200 out in use now and they work great. It is based around our JB+ gasoline tuner of which there are over 2500 out over the past few years with zero reported issues. We've monitored EGT among other parameters and feel the algorithm used is well within the safety limits of the BMW diesel motor.

It's based around an 18F processor @ 8mhz. A much simpler processor could handle the task but we just used the faster than needed 18F for it as we use them in other applications and buy them in bulk. I don't believe the tuning can be easily implemented using discrete components (e.g. resistors/diodes/caps) as it requires many non-linear functions. It would take a circuit board full of components vs. a using a single micro controller with atod/dtoa.

The inside of the JBD is similar to our JB+:



We have a 14 day guarantee on them and are happy to extend that to 30 days if any xpost users would like to do an extended comparison, dyno testing, etc.

The JB4 for gasoline motors is a much more complex product, featuring can integration, built in code reading/deleting, in dash gauges, steering wheel control map switching, and huge power gains. But if you have a 335D or X5D our JBD tuner is one of the few options for gaining power while avoiding codes on USA spec cars.