M50 injectors, new fuel filter/pump = knock

[Varinn]

Had some issues a couple weeks ago when I installed m50 injectors from MaksV and got a large FPR oring leak that I fixed easily. After fixing the leak, the car would not start, just crank but not catch. I tried a few things over the next week with no results. Ended up being the fuel pump had died, replaced it with a brand new VDO unit and installed a new fuel filter. Car fired up easily but it's running extremely rough and knocking at idle now. This was not an issue before, is it possible that it's overfueling so much it's causing the knock? Is there fuel in my oil that could cause the bearing to be damaged? I'm going to do an oil change and swap back to stock injectors before driving it any further.

My best guess is that having the battery dead for a week caused the DME to reset and combined with higher flow from pump and bigger injectors its causing it to do this.

[603Racing]

Larger injectors by themselves would not cause a knock. First thing I would do is check to make sure everything is connected/installed correctly. If you don't find any issues, put the old injectors back in.

Some additional info on your car/motor would help too. What motor? ECU? Chip? Injector part number? You get the point.

[Varinn]

Attempted to start it again this morning to double check symptoms and it's once gain refusing to start. Cranks for days with no catch, but you can hear it trying. Only thing I can think of is putting it back to 100% stock and going from there.

Its a 1990 325i, stock motor aside from injectors and a custom tune from a local tuner. (which i've had for a while with no problems)

[dnguyen1963]

Are the plugs wet with fuel? Your injectors might be dumping too much fuel upon start up.

[Varinn]

I didnt have time to check the plugs today, but tomorrow morning I'll be putting the stock injectors and chip back in and new plugs/wires (if I can find wires for under $200 local, so far no luck).

[603Racing]

If you have a custom tune and are putting injectors on the motor that aren't part of the tune that's probably your issue.

For the most part larger injectors usually don't cause no start issues by themselves, but you have a tune... that's the only variable I see.

I had both 19# and 17# injectors in my car with no tune, they didn't do much except make the idle a bit rich. I put a MarkD chip in with 17# injectors, much better.

I'll get to the point now. :zzz: Go back to the injectors that were part of the custom tune or get the tune updated for the larger injectors.