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      09-23-2024, 04:21 AM   #1
Yaabdelgawad
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Drives: 2009 bmw 335xi
Join Date: Jan 2024
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2009 Bmw 335xi  [0.00]
N55 crank no star after motor swap

Hey everyone, I’m in a frustrating situation with my car, and I can’t seem to figure it out. I bought a beautiful six-speed 2011 BMW 335xi back in May from an older gentleman, but it had a seized motor. After owning the car for about a month, I confirmed that it needed a new engine. I sourced a replacement motor from a reputable junkyard, and before installation, I replaced the valve cover gasket and oil filter housing gasket, even though there were no signs of leaks.
I then removed the front end of the car, pulled the bad motor out, and swapped over everything from the old engine to the new one, including the wiring harness. After getting the new motor installed, I tried to start the car, but it only cranked without starting. I went through everything—checked the grounds, ensured everything was properly connected—and everything looked perfect.
I suspected the ECU might be the issue, so I sent it out for testing to “The ECU Pro,” and they confirmed that the ECU started their test car, ruling out that as the problem. I reinstalled the ECU, but the car still cranked without starting.
Next, I thought it might be the crankshaft position sensor, so I swapped it with the one from the old engine, but still no luck. I also replaced the camshaft sensor from the old motor. The only codes I’m getting are from the axles not being in the car and from the front end components (like the headlights, intercooler, and fan) not being installed yet.
I know the car is getting fuel because when I loosened one of the fuel rails, fuel sprayed everywhere, and it’s obviously getting air. However, there’s no spark. I’ve checked all the wiring on the ignition coils, which looked fine, but just to be sure, I replaced the ignition coil harness. Unfortunately, that didn’t fix anything either. I also tested for spark using a spark tester and confirmed that I’m still getting no spark at all.
All fuses are fine, and I’m running out of ideas. The last thing I can think of is that maybe the timing is off. But how can I check that for sure? Could the timing being off really cause a no-spark issue? I’m not even sure if it’s something I need to check, but at this point, I’m open to anything. Could the lack of coolant in the system also be a factor, even though I don’t think that’s likely?
Any help would be greatly appreciated. Thanks for taking the time to read this.
Appreciate 0
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