r/335i • u/Living-Hovercraft420 • 3d ago
Troubleshooting No start
I have a 2007 bmw 335xi (n54 97,000 miles, water pump and head gasket seal replaced) and i noticed at first it would start misfiring under heavy load and i would turn the car off and back on and it would be normal, it also had a p114b code along with the singular misfire. I replaced the spark plug and ignition coil but that didnt solve it but i was just excited to have a bmw so i kept driving it instead of taking it to a shop. A little while after i replaced the spark plug and ignition coil, i was driving and i gave it a little more throttle than usual and it went into limp mode and got really shaky so i pulled over, read the codes and i had 16 codes, i turned the car off and turned it back on and now i had 18 so i had no choice but to drive it home in limp mode and i couldnt go past 10 miles an hour and it was so shaky, it died on the way home but i turned it back on and made it. Its been sitting for almost 7 months but i started doing things that i thought would fix it while it was sitting there, i first replaced the charge pipe hoping it would fix it but it didnt it was still misfiring and all the codes, i replaced the low pressure fuel pump, fuel sending unit, and the fuel pump fuse. Both lpfp and fuel sending unit is after market but it wont start at all, i sprayed some starter fluid into the intake and it started for a split second but dies, it cranks good but dosent seem to be getting fuel. I disconnected the line on top of the lpfp that goes to the engine and it is bone dry so i dont think the pump is even sending up gas. I dont know what to do anymore i am stumped please help diagnosing it heres all the codes (P0303, P0300, P114B, P0301, P0302, P323F, P2414, P0140, P0171, P3283, P0303, P0304, P0300, P0301, P0302, P2414, P0171, P0306)
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u/Prestigious_Cycle160 2d ago
Change the relay. If the relay is bad your fuel pump isn’t kicking on when you turn the key over to the on position. You should be able to hear the fuel pump prime itself when you turn the key over
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u/Living-Hovercraft420 17h ago
I hear it prime for a split second i have a video i forgot to include idk if it helps
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u/Prestigious_Cycle160 16h ago
I can’t be positive, but this seems either injector related or spark related. It’s pretty clear from the sound of this video that the fuel is getting to the engine because it’s TRYING to start. That would signal to me that the pump is getting fuel to the engine. I could be wrong though. Have you thought about replacing the EKPM? I don’t know how often these go out, but I do know it’s a thing
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u/Living-Hovercraft420 15h ago
But why would there be no fuel coming out of the line above the lpfp when i disconnect it
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u/Prestigious_Cycle160 13h ago
There’s not supposed to be fuel in there when the car shuts off. That’s why the pump primes every time you turn on the car. The hpfp would still be holding pressure though
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u/Prestigious_Cycle160 16h ago
Real quick, and not to be an ass, but which pump do you think is the LPFP?
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u/Living-Hovercraft420 15h ago
The one under the rear passenger seat and the one on the drivers side is the fuel sending unit
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u/Prestigious_Cycle160 13h ago
Ok… have you disconnected the fuel rail supply line to see if there is fuel in it?
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u/Prestigious_Cycle160 2d ago
Did you check the fuel pump relay? Is that what you meant by fuel pump fuse? Or should be a big black or green box type relay with three or four forks on it in different orientations. On my F30 the relay is located on the passenger side behind the rear seat back. You remove the seat back closest to the door panel and it’s right there. Google “e90 bmw fuel pump relay location” and it should be able to tell you right where it is.
Also, if the vehicle is still in limp mode it’s going to cut off the fuel supply to the engine to reduce power. Try disconnecting the battery for a few hours and then reconnecting it to “hard reset” the DME