N54 wont idle

08TUNDRA · 09-21-2018, 12:37 AM

Hi everyone need a bit of help on what to do next on an n54 that in trying to fix. Tried researching but everyone else doesnt seem to have the same symptoms. The idle on this car is fine for a few seconds when cold, as soon as it begins to drop it begins to jump up and down it drops under 500rpm and alsmot stalls then jumps back up. It does this whether its cold or warm Ac on and off. Just bought the car. Put brand new spark plugs, brand new coils, all new vaccum lines, walnut blast, hpfp is new, swapped out injectors and coded with no change, cleaned the MAP sensors, cleaned the vanos solenoids, swapped boost solenoid. All with not much result . The car pulls hard and is good all stock. Stumped at this point. I attached a youtube video so you guys can see. Any help is appreciated!

RomKaN54 · 09-21-2018, 09:43 AM

i have same issue replaced the coils, plugs, and index 12 injectors just improved a little but issue still there.... what i did is used MHD to disable "cold start" and set idle to 800rpm... 2 years running no issues. u in san diego warm climate like me so u will be fine.

08TUNDRA · 09-21-2018, 10:16 AM

Quote:

Originally Posted by RomKaN54

i have same issue replaced the coils, plugs, and index 12 injectors just improved a little but issue still there.... what i did is used MHD to disable "cold start" and set idle to 800rpm... 2 years running no issues. u in san diego warm climate like me so u will be fine.

That might be what I have to do. Just got the car and wanted to make sure the whole engine was sorted before I tuned it. But hey if a tune can fix it I'm all for it !

RomKaN54 · 09-21-2018, 10:31 AM

car is ready just pull the trigger!!

JM98 · 09-21-2018, 10:38 AM

I had similar symptoms with a vacuum leak at the throttle body

arhoads335i · 09-21-2018, 11:08 AM

yup I would guess vacuum leak

08TUNDRA · 09-21-2018, 04:34 PM

Quote:

Originally Posted by RomKaN54

car is ready just pull the trigger!!

I will very soon!, just gotta make sure everything is sorted and then the mods begin!

08TUNDRA · 09-21-2018, 04:35 PM

Quote:

Originally Posted by JM98

I had similar symptoms with a vacuum leak at the throttle body

Will take a look at that, maybe there is a crack?

08TUNDRA · 09-21-2018, 04:37 PM

Quote:

Originally Posted by arhoads335i

yup I would guess vacuum leak

Any way to test vaccum leaks on these cars? All the hoses are new.. dont know where to look next.

Bali · 09-22-2018, 01:20 AM

Smoke test for vacuum leaks.

Read the trouble codes and warm idle fuel trims.

09-21-2018, 12:37 AM	#1
08TUNDRA Lieutenant 125 Rep 445 Posts Drives: 2008 e92 335i Join Date: Jul 2014 Location: San Diego CA iTrader: (6)	N54 wont idle Hi everyone need a bit of help on what to do next on an n54 that in trying to fix. Tried researching but everyone else doesnt seem to have the same symptoms. The idle on this car is fine for a few seconds when cold, as soon as it begins to drop it begins to jump up and down it drops under 500rpm and alsmot stalls then jumps back up. It does this whether its cold or warm Ac on and off. Just bought the car. Put brand new spark plugs, brand new coils, all new vaccum lines, walnut blast, hpfp is new, swapped out injectors and coded with no change, cleaned the MAP sensors, cleaned the vanos solenoids, swapped boost solenoid. All with not much result . The car pulls hard and is good all stock. Stumped at this point. I attached a youtube video so you guys can see. Any help is appreciated! __________________ 2008 E92 335i-MHD FBO-6MT Conversion- CIC I-drive Retrofit
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09-21-2018, 09:43 AM	#2
RomKaN54 Enlisted Member 23 Rep 38 Posts Drives: 2009 335i 6MT Join Date: Mar 2011 Location: Gilbert, AZ iTrader: (0)	i have same issue replaced the coils, plugs, and index 12 injectors just improved a little but issue still there.... what i did is used MHD to disable "cold start" and set idle to 800rpm... 2 years running no issues. u in san diego warm climate like me so u will be fine.
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09-21-2018, 10:31 AM	#4
RomKaN54 Enlisted Member 23 Rep 38 Posts Drives: 2009 335i 6MT Join Date: Mar 2011 Location: Gilbert, AZ iTrader: (0)	car is ready just pull the trigger!!
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09-21-2018, 10:38 AM	#5
JM98 Lieutenant 391 Rep 532 Posts Drives: 2009 135i Join Date: May 2016 Location: SoCal iTrader: (0)	I had similar symptoms with a vacuum leak at the throttle body
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09-21-2018, 11:08 AM	#6
arhoads335i Captain 180 Rep 772 Posts Drives: 2015 435i grand coupe xdrive Join Date: Jan 2017 Location: Philadelphia, PA iTrader: (3) Garage List 2008 BMW 128I [0.00]	yup I would guess vacuum leak __________________ 2015 435i grand coupe xdrvie (current) 2006 F250 powerstoke CCSB (current) 2014 M235i Black on Red (SOLD) / 08 e90 335i MT Pure Stage 2 High flow (SOLD) 08 128i 6MT (SOLD) / 08 335i 6MT Pure stage 1 (SOLD)
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09-22-2018, 01:20 AM	#10
Bali E46 Fanatic 41 Rep 152 Posts Drives: E46 E84 F15 Join Date: Aug 2014 Location: Riverside, CA iTrader: (0)	Smoke test for vacuum leaks. Read the trouble codes and warm idle fuel trims.
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