Quote:
Originally Posted by thewheelm4n
This is so crazy man...I'm 6 months and $4k into mine and still no resolution to 4580 issue. Same symptoms really, usually low no lower power mode on the highway or cruising but as soon as I come off an exit ramp and come to a stop, bam there it is almost every time. Makes me think its some sort of low pressure issue. I had the shop its been at for the past 4 months, who found that bulletin regarding fuel return lines, replace the 3 fuel return lines, but still didn't fix it. At this point I'm at a loss, I've got one more shop to try locally but of course they can't even get me in until October 13th. I'm totally out of money and motivation to keep at this but I have a loan on the car so I have to fix it even if I'm going to try to sell it. Unbelievable. Any progress?
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Unfortunately no progress on my end. I'm basically narrowing it down to replacing one of these components, either choice is bad since it will cost close to $1000 per area:
LPFP & Sending Unit
-Overall, code 4580 seems like a mechanical fault, like something is causing the blockage of the return fuel. Both the LPFP and it's sending unit have these 'pressure relief' valves that might cause the pressure build up. I tried searching online to purchase only these valves, but they don't seem to be sold separately, so have to buy the fuel pump+sending unit to really eliminate those components as a cause of the fault
-I removed the return fuel line (in the engine bay) and tried to 'blow' through it and it was pretty difficult to do so, seemed like there's a lot of pressure in the line - meaning one of those 'pressure relief valves' are doing it's job? I know this sounds like a dumb test and I honestly don't know if there's supposed to be any pressure or just 'blow' through easily..
-A few members on the FB group suggested that my LPFP might be faulty and is 'pegged' at maximum flow during operation. Hence, when the vehicle isn't in idle, it's working fine. As soon as it idles, the pressure builds up since the LPFP doesn't reduce the flow. I tried to listen to the pump from the top of the rear seats and a few times it seemed to be working inconsistently.
-Planning to attach a pressure tested to the return lines and seeing what's happening with a mechanical gauge.
Injectors
-As I mentioned earlier, when I tested the injectors at the diesel shop, they all came back 'faulty'. The technician said that they might still work but they don't 'communicate' with the ECU. I only replaced (2) which was enough to make the vehicle run. So my though is, what if the remaining (4) that I left in are basically giving the ECU bad info on the flow rate, etc. That might mean that the ECU will use the fuel sensors on the HPFP & Rail to compensate/fix the fuel issue, possibly triggering the high fuel pressure?? It's just a theory, but I'm a bit more apprehensive thinking this might be injectors. However, 2 or 3 people on FB group told me the injectors fixed their 4580.
This is really where I'm at right now. I don't know which direction to go with, but I'm leaning more toward replacing the LPFP & Sending unit. I will keep you posted if I make any progress. Hang in there, we have to figure this out for the sake of the BMW Diesel Community
