135i build thread. I'm done hobcobbling posts together

[i_love_cars]

patsbimmer1 said:

Did the n55 have injector issues?

not as widespread as N54 but it does happen.

[suspenceful]

Which backend flash are you running? E85?

I know my E85 backend flash drops all cylinder timing to 9-10° right when I hit full boost. From there, it tapers up to 12-13° advanced. Looks to me like all of your cylinders (except #1) aren't advancing timing.

[i_love_cars]

agreed, there should be way more timing advance up top - what I don't know is just exactly what is throwing everything off. I am not ruling out the tune at this point either - I have a custom E85 BEF but I emailed Terry again about getting 98F0B posted. He never wrote a bef for that version of the n55 DME, which is frustrating. I sent him some data logs of what i currently have pleading with him because we talked 1.5 months ago and he said he'd write it but never did. 

I would really like to have that in my pocket to upload and test with to see if it is just a tuning issue on the back end. Hopefully he responds today.

[i_love_cars]

Here we fucking go. Terry got back to me today with a BEF for my DME version and VOILA. Car is running MUCH smoother and these logs are totally stable now with the proper ignition advance. Not a single thing wrong with any of the hardware on my car. Everything was tuning-related.

[i_love_cars]

Ok people, I went back to the dyno today after the tuning adjustments. Now the car is running where I thought it should've been to begin with. Very happy and I finally feel like I can call this car "done" in my eyes. I know some people are pushing the N55 further but in my opinion that's a $$$ rabbit hole that just isn't worth going down. At some point I'm going to sell this car and move into V8 territory.

475 whp / 477 wtq on E50 was my best pull today. The power band looks fantastic and I really couldn't be happier, especially knowing that I put all the parts on the car together myself and shit isn't blowing up. 

First 2 pulls were back at 21 psi same as what I had last week when I was making 420. When those looked clean I upped the targets to 23 psi in the midrange. Pull 3 had intake temps of 120 degrees so I had their dyno tech spray the engine down a bit before the 4th pull and picked up an extra 9 hp / 8 tq on the 4th pull.  23 psi in the midrange gave a really nice power increase between 4k and 5500 as you can see. 

[suspenceful]

That torque after turning up the boost!

I hope you're not still running lean. I saw your post on N54tech and looked at your logs.

[i_love_cars]

So far so good. N55's do run a bit more on the lean side anyway but my AFRs pull down to about 12.9-13.1 above 5400 rpm. Terry looked at logs I emailed him and said it looked fine but with the timing on the BEF I just don't see a 12.3 AFR happening without PI or meth. I don't think it's going to be anywhere near dangerous enough to lean out at those numbers, though.

[suspenceful]

i_love_cars said:

So far so good. N55's do run a bit more on the lean side anyway but my AFRs pull down to about 12.9-13.1 above 5400 rpm. Terry looked at logs I emailed him and said it looked fine but with the timing on the BEF I just don't see a 12.3 AFR happening without PI or meth. I don't think it's going to be anywhere near dangerous enough to lean out at those numbers, though. 

If you're comfortable with it, that's all that matters. If I were you, I'd richen it up with by adjusting the scalers in the BEF.

[i_love_cars]

I could get behind that logic

[i_love_cars]

After digging around a bit today, I'm deciding that I'm gonna stick to my guns with the current tune as planned. I sent the logs to Terry and he just got back to me and says the afr looks fine. His direct words were actually "the richer AFR on n55 leads to more misfires and headaches, which is why it's set where it is". You tune higher boost on these turbos to low 12's AFR you will actually misfire at higher rpm's. It goes against the convention of every other car I've ever owned being happy at about 12.3 AFR, but PURE's shop cars have the same thing so I'm not gonna worry about it. 

Here is one of their charts and the AFR is very similar to mine. They run about 12.9 sooner but above 4500 rpm they are still at 13.3 or so:

[suspenceful]

Leaner is meaner, let'r rip!

[i_love_cars]

seems that way. Just fuckin' weird. After your idea yesterday I second-guessed myself and emailed Terry immediately (as noted) and double-checked my research and while it all lines up, I just don't get it. 

To my understanding, even the N54 runs like, well, pretty much every motor you can think of, meaning it likes low 12's for AFR as the happy place. 

This is why I don't tune my own N55 and just leave it to someone who knows WTF they're doing

[suspenceful]

i_love_cars said:

seems that way. Just fuckin' weird. After your idea yesterday I second-guessed myself and emailed Terry immediately (as noted) and double-checked my research and while it all lines up, I just don't get it. 

To my understanding, even the N54 runs like, well, pretty much every motor you can think of, meaning it likes low 12's for AFR as the happy place. 

This is why I don't tune my own N55 and just leave it to someone who knows WTF they're doing

To be fair, I'm running about 13 under full boost to 12.6 by redline.