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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N55 Turbo Engine Tuning and Exhaust Modifications - 335i Tuning > **infamous n55 torque dip**



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      01-28-2011, 03:54 PM   #1
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**infamous n55 torque dip**

For the past year we have been noticing the horrible torque dip when dynoing the n55 motor.
Terry's n55 135i Notice the dip after 3krpms


Shiv's n55 135i Notice dip right after 2krpms


And here is mine 335i with ar design downpipe Scary I know.


A few people have asked why there is such a dramatic drop in tq, which led me to review my dynos. After comparing AFR with tq I have come to the conclusion that for some unknown reason the engine is running extra lean through those rpms..

Notice the huge drop in tq and how the car seems to lean out and start dropping again around 3700rpms and torque is restored.


*note that was a 4th gear pull*

These next pulls were done in 3rd gear with the


now we have the first flashed n55 in the US. It isn't easy to see but it does appear that they have better control of the AFR and have a much nicer tq curve with their flash.


This car can run and it pulls hard. I can see this car hitting 11's and trapping over 120 really easy. I hit a 12.95@107 with a 12.8psi max and thats with an extremely slow track(friend with n54 FBO, dual meath, race fuel was trapping 115 all night with a 12.09 1/4).

I can only hope that shiv, terry, and or cobb can grasp the fueling issue soon. It obviously has already been down with a flash but I don't see myself sending my ecu to florida anytime soon.

I guess I'll just sit back and wait till the n54 war is over and tuners can come back and give a little focus to the n55.
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      01-28-2011, 04:37 PM   #2
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Nice Ernie.

I have to bring it up
how about my baseline dynos (N55 6MT).
look at the curve between 3-4k
i'm still riding at 300 ft-lbs and not dip'n closer to 250 ft-lbs
-you know what, i have scoops - not that matters.

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      01-28-2011, 04:39 PM   #3
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Quote:
Originally Posted by FrankiE90 View Post
Nice Ernie.

I have to bring it up
how about my baseline dynos (N55 6MT).

What gear were you're runs?

And would you happen to have the afr? If you have the dyno files I can make them for you.
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      01-28-2011, 04:45 PM   #4
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Originally Posted by shockin330i View Post
What gear were you're runs?

And would you happen to have the afr? If you have the dyno files I can make them for you.
4th gear pull
tranny don't know.

I'll send u the files. pm
me ur email. overlay them to compare.
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      01-28-2011, 05:34 PM   #5
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i think is a boost adaptation issue because the car doesn't do than on the road , it seems to do this because a boost overshoot and sub-sequent wastegate duty cycle reduction.
i'm going to see if i can make it to the dyno tomorrow and i'll have some logs of the dyno runs and street runs so we all can compare.

BTW, did i mention my car is trapping 114.xx with 2.6 60' ?!?
And i'm getting some DR's on 17" wheels this weekend.....we'll see!

Last edited by black e; 01-28-2011 at 05:41 PM..
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      01-28-2011, 05:40 PM   #6
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the flash car run doesn't get richer then stock till 3500 RPM...if it was the case that the dip is caused because of a lean condition then i would have exepected the flash run to be richer sooner in the RPM range.
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      01-29-2011, 04:47 AM   #7
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hey blacke, what mods did you have when running 114traps? :-)
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      01-29-2011, 07:57 AM   #8
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i'll give a full list of current mods when i go back to the track with the DR's and get some good ET's...
here's the last time i ran good:http://www.1addicts.com/forums/showthread.php?t=460614
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      01-29-2011, 05:31 PM   #9
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here's my dyno from today, i will be making a new thread with all the details
red is map1 and blue is map0 , PROcede


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      01-29-2011, 05:48 PM   #10
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Originally Posted by black e View Post
here's my dyno from today, i will be making a new thread with all the details
red is map1 and blue is map0 , PROcede


13.5psi map 1? If you can, can you send me your dyno files?
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      01-29-2011, 05:57 PM   #11
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black e - really nice gains.
massive torque


Ernie.
from Alek
http://www.1addicts.com/forums/showthread.php?t=481996
DCT 135 11'
check out this curve.
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      01-29-2011, 06:12 PM   #12
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Quote:
Originally Posted by FrankiE90 View Post
black e - really nice gains.
massive torque


Ernie.
from Alek
http://www.1addicts.com/forums/showthread.php?t=481996
DCT 135 11'
check out this curve.
I really wish he would have started the rpms around 2k. He is starting over 3.5k rpms on every run. The dip would usually occur from 3k - 5k rpms. Notice black - e had the same dip. I wonder if I go back to the dyno and run after 3k rpms my car will run differently.
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      01-29-2011, 06:48 PM   #13
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Quote:
Originally Posted by shockin330i View Post
I really wish he would have started the rpms around 2k. He is starting over 3.5k rpms on every run. The dip would usually occur from 3k - 5k rpms. Notice black - e had the same dip. I wonder if I go back to the dyno and run after 3k rpms my car will run differently.



more on this later
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      01-29-2011, 06:51 PM   #14
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more on this later
You need to hurry with it. i'm bored at work lol
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      01-29-2011, 07:21 PM   #15
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I just installed my AR downpipe on my auto n55. I did a couple runs for the autotuning and everything went fine. Later on in the day the car would run amazing 1-2 then 3rd would start hesitating a bit. I double checked everything and no leaks. Any idea what that would be?
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      01-29-2011, 07:25 PM   #16
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I just installed my AR downpipe on my auto n55. I did a couple runs for the autotuning and everything went fine. Later on in the day the car would run amazing 1-2 then 3rd would start hesitating a bit. I double checked everything and no leaks. Any idea what that would be?
Are you running a tune?
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      01-29-2011, 10:17 PM   #17
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Quote:
Originally Posted by e92sport View Post
I just installed my AR downpipe on my auto n55. I did a couple runs for the autotuning and everything went fine. Later on in the day the car would run amazing 1-2 then 3rd would start hesitating a bit. I double checked everything and no leaks. Any idea what that would be?
Are you running a tune?
Yea I'm on procede v5
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      01-29-2011, 10:37 PM   #18
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Yea I'm on procede v5
How much boost?
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      01-29-2011, 10:48 PM   #19
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Quote:
Originally Posted by e92sport View Post
Yea I'm on procede v5
How much boost?
Map 2 which autotunes to 14. But on procede my car would always spike to 13.8 then make less boost as I would shift gears. By 4th gear it's at 11.5 lbs.

When I shift into third it feels like it's dying out. 1-2 is great but 3rd is noticeably different.
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      01-29-2011, 10:56 PM   #20
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Quote:
Originally Posted by e92sport View Post
Map 2 which autotunes to 14. But on procede my car would always spike to 13.8 then make less boost as I would shift gears. By 4th gear it's at 11.5 lbs.

When I shift into third it feels like it's dying out. 1-2 is great but 3rd is noticeably different.
My car does that too. The boost is there but it seems like it stays around 5krpms ad won't climb, the if I keep on it it shuts down. D u get offthe gas? Try wot from 1 to 4th and see I your car doesn't go into limp mode lke mine.
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      01-29-2011, 11:45 PM   #21
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Quote:
Originally Posted by shockin330i View Post
Quote:
Originally Posted by e92sport View Post
Map 2 which autotunes to 14. But on procede my car would always spike to 13.8 then make less boost as I would shift gears. By 4th gear it's at 11.5 lbs.

When I shift into third it feels like it's dying out. 1-2 is great but 3rd is noticeably different.
My car does that too. The boost is there but it seems like it stays around 5krpms ad won't climb, the if I keep on it it shuts down. D u get offthe gas? Try wot from 1 to 4th and see I your car doesn't go into limp mode lke mine.
Ill try that out tomorrow.

The car would hold boost alot better when I was running v4 and it was alot more consistent
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      01-30-2011, 12:08 AM   #22
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Ill try that out tomorrow.

The car would hold boost alot better when I was running v4 and it was alot more consistent
A few of us agree. I wish shiv would upload the v4 sw and maps so we could test them.
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