Cut wires on n54 jb4

EfiniMotorsport · 05-10-2021, 06:58 AM

I'm just about putting my car back together but having a few issues. I keep getting a code for the low pressure fuel sensor and after the car runs for a few mins it wont rev very well, to the point I cant even drive in reverse. I bought the car with a blown engine and put another engine in it but think there is some problems with the jb4. I think the jb4 had the nls 2step relay wired in but I've got 2 cars and cant remember which was which. Theres 4 wires that look like they were cut. There two long 20gauge wires coming off the usb plug and two more 20 gauge wires off the main plug. Not sure if they should be reconnected to each other or somewhere else. Name: 20210510_065500.jpg
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ewicky · 05-10-2021, 03:20 PM

What did BMS support have to say?

EfiniMotorsport · 05-10-2021, 03:25 PM

Haven't talked to them. They're customer support isnt great especially if I wasnt the one that purchased it originally.

Cloverdale · 05-10-2021, 09:13 PM

'think there is some problems with jb4'. You can disable jb4 through steering wheel controls which might help determine whether it's a jb4 related issue.

EfiniMotorsport · 05-10-2021, 09:24 PM

I removed it and changed the boost sensor (had a 3.5 bar in there) and the car runs fine aside from a lpfp sensor issue. I'm going to compare the harness to another one tomorrow and see what's different.

EfiniMotorsport · 05-11-2021, 08:45 PM

Reinstalled the JB4 with another harness and the NLS/2 step relay and it seems to run fine. I can't drive it right now but at least it idles and revs ok. One of the green wires from the USB plug is for the NLS relay but I have no idea what the other green wire is for. It is pinned next to the correct wire for NLS. I wasn't able to find any add-ons that would require one of the wires to the small DME plug to be spliced and only one of the wires from the large JB4 connector went to meth injection that wasn't installed on the car. I ended up using the cleaner harness when I reinstalled the JB4 into my car. I doubt it made a difference as everything was either added where there weren't already wires or were different color wires but still connected.

05-10-2021, 06:58 AM	#1
EfiniMotorsport Private First Class 52 Rep 131 Posts Drives: 335xi, Yukon Denali, 16 CRZ Join Date: Nov 2019 Location: Monroe, CT iTrader: (0)	Cut wires on n54 jb4 I'm just about putting my car back together but having a few issues. I keep getting a code for the low pressure fuel sensor and after the car runs for a few mins it wont rev very well, to the point I cant even drive in reverse. I bought the car with a blown engine and put another engine in it but think there is some problems with the jb4. I think the jb4 had the nls 2step relay wired in but I've got 2 cars and cant remember which was which. Theres 4 wires that look like they were cut. There two long 20gauge wires coming off the usb plug and two more 20 gauge wires off the main plug. Not sure if they should be reconnected to each other or somewhere else.
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05-10-2021, 03:20 PM	#2
ewicky Lieutenant 204 Rep 525 Posts Drives: '07 335xi 4D AT Join Date: Jan 2017 Location: Seattle, WA iTrader: (0)	What did BMS support have to say?
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05-10-2021, 03:25 PM	#3
EfiniMotorsport Private First Class 52 Rep 131 Posts Drives: 335xi, Yukon Denali, 16 CRZ Join Date: Nov 2019 Location: Monroe, CT iTrader: (0)	Haven't talked to them. They're customer support isnt great especially if I wasnt the one that purchased it originally.
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05-10-2021, 09:13 PM	#4
Cloverdale Second Lieutenant 123 Rep 257 Posts Drives: 2007 335i Jb4 & perf. mods. Join Date: Aug 2018 Location: Cloverdale, BC, Canada. iTrader: (0)	'think there is some problems with jb4'. You can disable jb4 through steering wheel controls which might help determine whether it's a jb4 related issue.
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05-10-2021, 09:24 PM	#5
EfiniMotorsport Private First Class 52 Rep 131 Posts Drives: 335xi, Yukon Denali, 16 CRZ Join Date: Nov 2019 Location: Monroe, CT iTrader: (0)	I removed it and changed the boost sensor (had a 3.5 bar in there) and the car runs fine aside from a lpfp sensor issue. I'm going to compare the harness to another one tomorrow and see what's different.
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05-11-2021, 08:45 PM	#6
EfiniMotorsport Private First Class 52 Rep 131 Posts Drives: 335xi, Yukon Denali, 16 CRZ Join Date: Nov 2019 Location: Monroe, CT iTrader: (0)	Reinstalled the JB4 with another harness and the NLS/2 step relay and it seems to run fine. I can't drive it right now but at least it idles and revs ok. One of the green wires from the USB plug is for the NLS relay but I have no idea what the other green wire is for. It is pinned next to the correct wire for NLS. I wasn't able to find any add-ons that would require one of the wires to the small DME plug to be spliced and only one of the wires from the large JB4 connector went to meth injection that wasn't installed on the car. I ended up using the cleaner harness when I reinstalled the JB4 into my car. I doubt it made a difference as everything was either added where there weren't already wires or were different color wires but still connected.
	Appreciate 0 Quote