On my post up above, was commenting how I just finished up my custom tune with David Shoup, and although logs and everything looks great, I have what is a noticeable slight stumbling at idle, car doesn’t die or have drive ability issues, it’s just when I’m at a dead stop, rpm’s fluctuate between 6-700 rpm’s. Was curious if any of you other guys that went mafless have this same issue. I do also have a transfer case insert bushing (70a polyurethane) so it could quite possibly be normal and maybe im just noticing it now, but its a definite consistent stumble that you can see and feel. Tuner said to try new plugs as he doesn’t think it’s tuning related being logs look perfect and it’s probably mechanical/hardware related. So gonna be giving that a shot this coming week. Again only happens at idle, the minute I give it any gas it goes away and idle logs look perfect, it’s almost as if the car is idling too low so the engine is compensating back and forth with the rpm’s. Also have a 2016 435i for reference and I know it’s not the exact same engine, that n55 doesn’t do it.
N55 Turbo Side Intake Progress
- Thread starter Alturiak
- Start date
JPuehl
Corporal
On the options when you flash an MHD tune, did you check the "fix the idle issue" checky box? I forget what the label of the option says exactly but can look. MHD made a fix for the fluctuating idle due to catless downpipe, but it hasn't really helped my issue. I've just learned to live with it.
I don’t recall seeing that box in the options, wasn’t that specifically for the dct n55s? I have a 2011 335i xdrive with the 6 speed auto, so I don’t think i have that box in the options, but I’ll go back and take a look
So are you going to be selling these ? Cause id prefer your intake to the only two options for Intakes I've seen.
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So just checked and yup I don’t have that option, I guess I’ll just have to live with it lol, looking online it looks like a common problem with these cars when tuned
So just an update to anyone that might be experiencing the same thing I was, I played around with some MHD and XHP settings, I raised the idle from stock to about 750 and through XHP I turned off the decoupling for when my car is at stops and it seems to have “fixed” or I guess somewhat bypass the idle issue. It was only happening between 6-700 rpms so by having it raised the car seems to be happier and no longer stumbling/ not as bad or noticeable as before
JPuehl
Corporal
By "decoupling" do you mean the no-creep setting? I do like that about XHP. For idle speed I set mine in the tune itself to 750 as I didn't like the way MHD did it when you set your idle as an option (it's been a while so I forget what I didn't like about it but I have mine set up to my liking)
Not essentially, I think for the 6 speed auto and the dct, it would actually be the opposite. With XHP deactivating decoupling means that the car’s torque converter is always locked in, instead of it opening up or “decoupling” when the car is in park or at a stop. On the autos when your at a stop there’s an initial lag before the car moves because the torque converter opens up when the car is stationary, with it opening up I was still noticing the stumbling, since the MHD idle raise option only works when the car is in park or in neutral, not in drive. With the decoupling shut off, the car is essentially always “in gear” when it’s in drive and it actually idles smoother for me anyway at stops and no more initial lag when taking off. When you say you set up your idle through your tune, how is it different compared to the way MHD is set up? I had asked David initially if he could tune it to where the car also idles at 750 for when the car is also in drive but he said he couldn’t, that that’s where the car will always idle just based on the torque converter and how the car is built. I’m assuming it’s different though with the DCTs because they act like a manual when at stops where they’re essentially in “neutral”.
So since deactivating decoupling, you no longer have that lag when hitting the gas from a complete stop?
Yessir no more initial lag, car just goes as soon as you give it gas
As we had a big drop by MHD yesterday, and it’s Jay-Z’s birthday today I thought they were the perfect excuses to give a little update on this thread. 
Engine bay currently looks like this. It all fits, it’s just a bit tight and like a ball of snakes by the power steering reservoir with the PPK2 hoses.
I bought an ER 2.5” turbo outlet which fits wonderfully, but only just. ER also cleaned the welds on the inside, so I didn’t have to!
The aFe filter I ordered finally arrived after months of waiting. It’s big and I should be able to get it to work! It looked like the most off the shelf filter area I could get in the space.
Here was my initial design for my shorty intake before the filter arrived (MAF mounting flange facing the cabin bulkhead). I will have to change things up a bit I think and still have to add in the PCV heater flange. I intend to print in plastic first, and then if all goes well, print in aluminium.
Engine bay currently looks like this. It all fits, it’s just a bit tight and like a ball of snakes by the power steering reservoir with the PPK2 hoses.
I bought an ER 2.5” turbo outlet which fits wonderfully, but only just. ER also cleaned the welds on the inside, so I didn’t have to!
The aFe filter I ordered finally arrived after months of waiting. It’s big and I should be able to get it to work! It looked like the most off the shelf filter area I could get in the space.
Here was my initial design for my shorty intake before the filter arrived (MAF mounting flange facing the cabin bulkhead). I will have to change things up a bit I think and still have to add in the PCV heater flange. I intend to print in plastic first, and then if all goes well, print in aluminium.
Looking great, nice update!!As it’s Jay-Z’s birthday today I thought they were the perfect excuses to give a little update on this thread.
Attachments
Thanks! Yeah, I have ‘scanned’ in the standard MAF profile of which the perimeter is just under the size of 4” round tube. I’ve then transitioned that profile to the filter on the one side and to the turbo inlet on the other. The (straight) MAF section length is the same as on the standard air inlet assembly, so the MAF readings should be bang on. I’ll report back once it’s printed.
The PCV hose will go across the engine to a catch can on the strut bar (by the charge pipe) and then back across into the standard PCV heater into the shorty intake/inlet. (I will put an appropriate port on the shorty intake.)
You should try this, will be shorter and cleaner
Make sure it’s the passenger side mount, as there’s 2 options. Look in the install instructions for more pictures, mounts right next to the washer fluid reservoir cap and you can rotate the can for us n55 guys. Gonna be customish with the hoses though
Make sure it’s the passenger side mount, as there’s 2 options. Look in the install instructions for more pictures, mounts right next to the washer fluid reservoir cap and you can rotate the can for us n55 guys. Gonna be customish with the hoses though
Thank you! I tried to position my Mishimoto can on the exhaust side on the strut brace, but there’s no room for a can of that size there. Maybe a smaller can and a specific bracket like you’ve linked, but I’ve already got a nice RB strut brace bracket to hold it to the brace and the -12 hose is pretty big bore so I’m going to try that first. On the intake side the can is not sat above the exhaust manifold so it may be easier for the vapours to condense? Maybe not as good as a short hose routing though.
