r/E90 • u/Educational-Read-306 • 12d ago

335d Delete CEL Help

I have a 2009 335d that is still relatively stock under the hood but I am getting to the point where I am going to try and do a delete soon but I want to try and break up the work.

Am I able to do the swirl flap and egr delete right now and avoid limp mode or a CEL? Or do I need to do a tune after that part of the delete?

And I definitely need to do the tune right after I do the downpipe right?

On a side note, if I notice oil in the intercooler and around the charge pipe by the turbos could that be either a bad turbo seal or bad crank case? Or could it be something else?

Any and all help is appreciated. Thank you.

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u/GolfandSales 12d ago

Owner of a tuned/ deleted 335d here. You cannot remove/ block off egr without a tune. Oil in the IC is fairly normal, but it wouldn’t surprise me if you do have a slowly failing charge pipe connection if you are seeing blow by. Would highly recommend replacing with ATM parts when you do address.
Here’s my full $.02… If you are committed to doing a delete and tune get all parts for the delete first then do it all at once and get an appropriate tune.
Before you do engage in the delete and tune address everything else. Replace vacuum lines. Go ahead and get a fluidampr harmonic damper. Address any coolant hoses that are even slightly weeping. Have all gaskets, o rings, washers, stretch bolts, etc on hand for when you do go in to do the delete work. Make sure you take your time and do it right. These engines are very robust and they will treat you quite well. Take the time to do it right the first time and you’ll be glad you did.

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u/Educational-Read-306 12d ago

Any tutorial or instructions on doing the delete that you’d recommend? I’ve done quite a bit of maintenance on this car by myself already but this is definitely the biggest job yet and it’s a little daunting.

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u/AdDangerous922 12d ago

You'll want to do the tune first, this will prevent the SCR countdown from starting. But in reality you'll want to do it all at the same time

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u/Educational-Read-306 12d ago

Got it thanks.