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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Leaky injector?



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      08-27-2020, 11:05 AM   #1
Mustafa.e92
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Leaky injector?

Hey guys does this look like a leaky injector small puff of black when cold start. Sat for a day. I'm getting some hesitation higher rpms maybe correlated?? Hard to log with Cobb, Cable for mhd coming this week no more Cobb
(Won't let an add the video) small puff of black smoke then it goes away
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      08-27-2020, 11:13 AM   #2
iqraceworks
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Let the car sit overnight. In the morning pull all the spark plugs out. If any are wet, or even smell like gas....you have a leaky injector in that cylinder.

That's the only way to know for sure.
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      08-27-2020, 11:28 AM   #3
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Good for you getting MHD. Pulling the plugs like IQ mentioned is your best bet for finding a leaky injector, although you can pull them after a couple hours if you'd like to find out sooner. I also like to stick a tube in the plug hole of the cylinder and smell through that if I can't totally tell by just smelling the plugs. That makes it really obvious.
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      08-27-2020, 11:34 AM   #4
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Quote:
Originally Posted by stewbets View Post
Good for you getting MHD. Pulling the plugs like IQ mentioned is your best bet for finding a leaky injector, although you can pull them after a couple hours if you'd like to find out sooner. I also like to stick a tube in the plug hole of the cylinder and smell through that if I can't totally tell by just smelling the plugs. That makes it really obvious.
Thanks
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      08-27-2020, 04:28 PM   #5
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Once you have MHD you can log parameters to get a better idea of what's going on and see if you really may have a leaky injector and if so on what bank.

While the smell test is a good indicator, I had some plugs that smelled of fuel and my AFRs when letting off the throttle indicated a leak. I replaced all of the injectors and it turns out it was actually an old faulty pre-cat O2 sensor. I think if a plug smells horribly of fuel then you have a leak although mine smelled pretty bad.

There is a test where you pull all 6 injectors out, unplug the electrical connections to each injector but keep the fuel lines intact with the injectors pointing towards the drivers side. Then crank the car and if one of them starts spraying that's the leaker. Just be sure to replace and compress the injector seals before putting them back into the engine.

What index injectors do you have? If they are not index 12 it wouldn't hurt to replace anyways with some from FCP euro and get a lifetime warranty.
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      08-27-2020, 04:31 PM   #6
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Quote:
Originally Posted by colman View Post
Once you have MHD you can log parameters to get a better idea of what's going on and see if you really may have a leaky injector and if so on what bank.

While the smell test is a good indicator, I had some plugs that smelled of fuel and my AFRs when letting off the throttle indicated a leak. I replaced all of the injectors and it turns out it was actually an old faulty pre-cat O2 sensor. I think if a plug smells horribly of fuel then you have a leak although mine smelled pretty bad.

There is a test where you pull all 6 injectors out, unplug the electrical connections to each injector but keep the fuel lines intact with the injectors pointing towards the drivers side. Then crank the car and if one of them starts spraying that's the leaker. Just be sure to replace and compress the injector seals before putting them back into the engine.

What index injectors do you have? If they are not index 12 it wouldn't hurt to replace anyways with some from FCP euro and get a lifetime warranty.
I already have index 12, I'm probably gonna pull the plugs out of curiosity. Hoping to post some logs soon to get some input on how the cars performing
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