random misfire when first applying throttle 3.0

[freedo]

i have a 2001 3.0 5spd with 235k on it. just recently it started doing this weird stutter (misfire) when first applying throttle to accelerate from a stop and after shifting gears. it is no consistent and after the quick stutter and drives and cruises like normal. i thought at first it was load related but i am able to replicate it at a complete stop and in neutral by just give it a little gas. doesnt happen every time though and has not thrown any misfire codes. current codes are for a bad secondary air pump and for the O2 sensors. it had a fuel pressure code for low fuel but that self cleared and hasnt been back after 200 miles of driving. i have emptied a entire can of brake clean around the intake and noticed no change in idle (i made sure it was the flammable stuff) i am stumped on where to look next. plugs were done 10,000 miles ago and still look good, i dont hear any obvious vacuum leaks and found none with the brake clean. any ideas on where to look next? i do have a oil leak under the intake somewhere so i am planning on pulling the intake to investigate and replace stuff so if anyone has a list of items i should replace once the intake is off please let me know. thanks for any help

[80stech]

Primary suspects are plugs and coils.

[Bdc101]

What caused the low fuel pressure code? Others on this forum have suggested that fuel pumps can fail gradually. I have never heard of that happening but it's come up in suggestions on this forum several times that I've seen.



What are the O2 sensor codes as well... and how are you pulling codes, Foxwell? PA Soft? PA soft always throws an O2 short circuit code for me, but it's not a real code, and doesn't show up in my Foxwell.

[80stech]

There is no such thing as a fuel pressure code.

[freedo]

Originally Posted by Bdc101

What caused the low fuel pressure code? Others on this forum have suggested that fuel pumps can fail gradually. I have never heard of that happening but it's come up in suggestions on this forum several times that I've seen.



What are the O2 sensor codes as well... and how are you pulling codes, Foxwell? PA Soft? PA soft always throws an O2 short circuit code for me, but it's not a real code, and doesn't show up in my Foxwell.

my bad, it was a low fuel misfire code (i did run it a bit low) but it self cleared after a fill up. my scanner its just a generic scan tool. O2 codes are p0160 and p0140. my scanner reads that as O2 sensor circuit no activity detected bank 1 (and bank 2) sensor 2. i am getting my e36 tuned this week so i may see if my tuner can scan it with his computer as i have had the issue you are stating where it says one code but it means something completely different. i also had a P1447 diagnostic module tank leakage (DM-TL) pump current too high (solenoid test) but that also self cleared and hasnt returned

[freedo]

Originally Posted by 80stech

There is no such thing as a fuel pressure code.

my bad, it was a low fuel misfire code (i did run it a bit low) but it self cleared after a fill up. i was typing that off if memory and got low fuel and low pressure mixed up

[Effduration]

Could be many things.

As a first step, I would measure fuel pressure at the rail at idle and while driving.
Needs to be close to 50 psi steady.

As a second, I would do a proper smoke test (not a fluid pump/cigar job) with good smoke and pressure for 10 minutes..

The flammable brake cleaner test for leaks won’t work as the DME will adjust before you hear a difference.

[Bdc101]

I would suggest getting a proper BMW scan tool as the first step, since he hasn't done that yet. Especially if the OBDII codes for the O2 sensors are real.

[freedo]

using inpa (its in german so using phone to translate) we got code
241 which seems to be cyl 4 misfire
142 module error DMTL
190 and 191 which is oxygen sensor 1 and 2
39 BLS-BTS plausibility
153 lambda probe voltage mach-KAT probe

i drove it at highway speeds while towing about 100 miles a couple days ago. still did the stumble occasionally on initial tip in of the throttle when pulling from a stop or shifting gears but after that it was smooth sailing

[freedo]

bump