Well we don't know how many miles each of these units have, which would contribute to the burn area I would imagine, not to mention whether they were used with a stock pump or a higher drawing pump.
These two boards have significantly different layouts and components. I suppose I'd wonder if they were not improvements? Are you thinking HW06 is actually a "downgrade" so to speak?
EKP for pump management has been used on a number of later cars as well - not to make all of this more complicated, but there are further revisions. No idea if they are compatible beyond pin out.
You don't know, but chances are they were used with the stock pump. A lot more cars are running the stock pump than an aftermarket one. A lot.
I would not call the HW 06 a "downgrade". What we are doing to beyond the scope of the design goals. We may find that the HW 04 performs better when pushed beyond it's limit, but from the scope of the stock fuel system it isn't a downgrade. There are many different design goals the engineers balanced and the functional current and operating temperature are just two of them.
There are a couple reasons you would need to redesign a module like this. The obvious one is features. The old module doesn't do something the new module needs to. While that may be true in some application in the E90 with a stock pump EKPM2 = EKPM3 HW 04 = EKPM3 HW 06. They are interchangeable.
Along the same lines is if the module needs to change in size or shape. The EKPM3 HW 06 is physically shorter then the HW 04 and the EKPM2. You can see near the microcontroller (square black part top middle) on the EKPM3 HW 04 there is a good amount of extra space. The HW 06 is more space optimized. If this was done to make the module fit in tighter spaces I don't know.
Another reason is cost reduction. I don't know if I see evidence of that here. I am pretty sure the EKPM3 costs less to produce than the M2 because the switch is now integrated with the driver, but I suspect the EKPM3 was designed primarily due to part obsolescence. However, reducing the board size and the size of the housing could be cost reduction. Less materials are used leading to less overhead. When the boards are produced a primary driver of the cost of the board itself is area. A primary driver of the PCB assembly (boards plus parts) are the number of unique components. This module must be used in millions of cars so even cents matter here.
Another reason is part obsolescence. Manufacturers don't make the parts on the board forever. Eventually the module needs to be redesigned to continue to be able to be produced. That is what I think happened with the EKPM2. The parts on the M3 are completely different, and definitely more modern.
Another reason is regulatory compliance changes. You can see on the bottom of the EKPM3 HW 06 there is a symbol for "lead free". The previous versions are not marked with the symbol in any way. RoHS regulation change over time. The EU has a set of standards and China has its own. I think the US largely uses the EU standards, but environmental compliance isn't my thing. I do know that RoHS II is much more strict than RoHS I was and this can drive changes to the design, even if it is just to use lead free solder because the exemption that allowed leaded solder to continue to be used is no longer valid.
You bring up an interesting point about the EKPM3 in the newer cars (F and G chassis). From looking at Real OEM it is not clear that the new modules will work in an place of an older one. The parts numbers of the new modules are not listed as "Supersedes". If you search for the current number for the E90: 16147407513. If you search for that number what you find is a "HW 07" version.
This is not the same as for the F or G chassis. For these cars you would find a 16147411596 (current) for earlier cars or a 16149452468 (current) for later cars. The earlier one uses a different revision number system such as "HWEL 000.001.003". The later one is difficult to find pictures of because the cars are so new. I did find pictures of 16148488591 (which was superseded by 16149452468) in an
Ebay listing.
When I purchased an EKPM3 from Ebay, I ended up with 16147218339 which is a HW 04 version. I bought it because of the layout change from HW 04 to HW 06 appearing to be worse for thermals and because it was sure to work in my car (2007 E90 VB73) over one with a "HWEL" hardware revision number.
I suspect any EKPM3 or M2 will work with our cars, but I made sure to purchase a version Real OEM said was compatible. It would be interesting to pop the top off of one of the newer ones with the "HWEL" revision numbering system. I do not think the ones in the G chassis will work. They have a completely different connector, but maybe they are the same inside. Who knows.
