[johnung]

It appears that F3x N55 engines either came stock with EU6 fuel injectors or with the higher flow EU5 injectors. Does anyone know if there is a reason why?

My 2015 335ix probably has the EU6 injectors that I’m about to replace to ward off some leaks. I was told that the flow of the EU6 is more than enough for an N55 engine upgraded to E85 with a Pure500 turbo upgrade (500+ hp).

If that’s true, is there any other reason to upgrade to the higher flow EU5 injectors? Is more flow the only difference between them? Different spray pattern? more reliable? Better for higher HP? Handles E85 better?Any reason at all? Cost isn’t really an issue, only $56 more total.
Thanks!

[NEWTRON]

Originally Posted by johnung

It appears that F3x N55 engines either came stock with EU6 fuel injectors or with the higher flow EU5 injectors. Does anyone know if there is a reason why?

My 2015 335ix probably has the EU6 injectors that I’m about to replace to ward off some leaks. I was told that the flow of the EU6 is more than enough for an N55 engine upgraded to E85 with a Pure500 turbo upgrade (500+ hp).

If that’s true, is there any other reason to upgrade to the higher flow EU5 injectors? Is more flow the only difference between them? Different spray pattern? more reliable? Better for higher HP? Handles E85 better?Any reason at all? Cost isn’t really an issue, only $56 more total.
Thanks!

The difference between N55 eu5 and eu6 is the spray pattern. It was changed to get better emissions. M5 eu5 injectors are the ones that flow more. M5 eu5 injectors are going for $900 vs $600 for the n55 Eu6

https://www.fcpeuro.com/products/bmw...h-0261500136kt

https://www.fcpeuro.com/products/bmw...-13647639994kt

You will be fine with eu6 injectors for a pure500.You'll run out of turbo before you do injector. EU5 or upgraded injectors are really only needed for 600+whp. I've been running EU6 injectors for 3 years on a pure stage 2 and E50.

[johnung]

Originally Posted by NEWTRON

The difference between N55 eu5 and eu6 is the spray pattern. It was changed to get better emissions. M5 eu5 injectors are the ones that flow more. M5 eu5 injectors are going for $900 vs $600 for the n55 Eu6

https://www.fcpeuro.com/products/bmw...h-0261500136kt

https://www.fcpeuro.com/products/bmw...-13647639994kt

You will be fine with eu6 injectors for a pure500.You'll run out of turbo before you do injector. EU5 or upgraded injectors are really only needed for 600+whp. I've been running EU6 injectors for 3 years on a pure stage 2 and E50.

Thanks for the input! So if max flow is more than enough for a tuned N55 engine with a Pure500 upgrade, of the N55 EU6 and N55 EU5 injectors,

1) I wonder if one spray pattern is more beneficial than another, and
2) I wonder if EU6 or EU5 is more reliable/less prone to leaks?

My reason for replacing injectors now is:

1) the many comments that I’ve read about leaking injectors causing damage,

2) I have a symptom when my tank has >E50 and the car sits all night, in the morning it has great difficulty starting, as if the engine is flooded. As the ambient temperature drops it gets worse. Been told that a slow leak from an injector will flood the cylinder overnight.

To change from a non-stock injector is it just simple coding in E-Sys or ISTA?.

[thejeremyman9]

Originally Posted by johnung

2) I have a symptom when my tank has >E50 and the car sits all night, in the morning it has great difficulty starting, as if the engine is flooded. As the ambient temperature drops it gets worse. Been told that a slow leak from an injector will flood the cylinder overnight.

To change from a non-stock injector is it just simple coding in E-Sys or ISTA?.

This is the nature of E85. Cold starts on higher ethanol content is because of the fuel itself, not an injector. And yes, it gets worse at higher ethanol content and worse at lower temperatures. So full E85 cold starts at sub 50F are going to be difficult.

[johnung]

Originally Posted by thejeremyman9

This is the nature of E85. Cold starts on higher ethanol content is because of the fuel itself, not an injector. And yes, it gets worse at higher ethanol content and worse at lower temperatures. So full E85 cold starts at sub 50F are going to be difficult.

I understand what you are saying. I can recognize the difference. I was using E85 for quite a while before the leaking injector symptom began. It reminds me of an old carbureted engine that is flooded.

There was a discussion about it and a method of troubleshooting by pulling the spark plugs was suggested. But I’m having some other work done so I’m just going to replace the whole set of injectors and be done with it.

[thejeremyman9]

Originally Posted by johnung

I understand what you are saying. I can recognize the difference. I was using E85 for quite a while before the leaking injector symptom began. It reminds me of an old carbureted engine that is flooded.

There was a discussion about it and a method of troubleshooting by pulling the spark plugs was suggested. But I’m having some other work done so I’m just going to replace the whole set of injectors and be done with it.

Gotcha. Would be interested to hear if replacing the injectors improves the high-E % cold start condition.

[johnung]

Originally Posted by thejeremyman9

Gotcha. Would be interested to hear if replacing the injectors improves the high-E % cold start condition.

I wouldn’t think so. It’s just physics. I learned pretty quickly the first winter that I had FlexFuel capability, not to run higher than E50 in the tank. It was a pain in the neck to have some warm days forecasted, put in E85 to collect some engine logs and then have the temperature drop suddenly.

[thejeremyman9]

Originally Posted by johnung

I wouldn’t think so. It’s just physics. I learned pretty quickly the first winter that I had FlexFuel capability, not to run higher than E50 in the tank. It was a pain in the neck to have some warm days forecasted, put in E85 to collect some engine logs and then have the temperature drop suddenly.

I thought you were just saying that you saw a difference in cold start that suggested a leaky injector, not just E85 fuel itself? Maybe i misread that.

[johnung]

Originally Posted by thejeremyman9

I thought you were just saying that you saw a difference in cold start that suggested a leaky injector, not just E85 fuel itself? Maybe i misread that.

Oh no. I think I misread your comment. I thought you were saying new injectors might clear up normal E85 cold start up issues, not just leaky injector. My bad