question for those w/ DPs and misfires

2wheelsrbetter · 06-28-2011, 01:12 PM

i've been getting misfires and 1/2 engine limp lately, mostly in morning when cold, sometimes when crusing just on/off throttle. i have a jb3 w/ O2 sims for my catless DPs. just cleaned intake valves (34k on clock and they were filthy btw), replaced all plugs, dealer just replaced hpfp and injector #6. 2 days after i got misfires on 4 5 & 6 again, but goes away after warm-up. i didn't save the codes but they were the same as i had before above work, pre and post lambda sensors.
my question is do i just need to tweak my O2 sims if this is only happening cold or cruising on/off throttle? i've adjusted a few times but i've been getting codes either way - been a pita to be honest, to the point where i want to put my stock DPs back on. car ran great before them.
anyone else have a similar issue??

bryce · 06-28-2011, 03:32 PM

all the bms o2 sim does is alter the signal from the secondary o2 sensors, to make it seem like there are cats still in place. pretty unlikely that the o2 sims are causing your misfires. it could be that the primary o2 sensor on bank 2 was damaged during the dp install, however.

onefastman · 06-28-2011, 08:35 PM

What if it's just on cylinder 5 even after I change my plugs and switch around the coils?

2wheelsrbetter · 06-29-2011, 12:34 PM

right but if i turn the O2 sim up or down too much the ecu would adjust with more or less fuel no? based on the before/after cat reading.

i thought maybe the sensor was damaged on instal, but i was REAL careful with them. also thinking it wouldn't be intermittent if something was damaged.

so it did it again this morning, i haven't pulled codes yet, just shut down and restarted. 10 sec in when start-up idle starts to drop, it goes real rough and then into limp.

reason i'm thinking it's sim related is that cyl 6 is still misfiring, after a new injector, new hpfp, new software, changing coil packs (coil pack is simply the plastic piece on the plug right?).

i haven't reset all adaptations, but i thought with getting new software from bmw that wouldn't be necessary. might try that tonight.

thoughts??

06-28-2011, 01:12 PM	#1
2wheelsrbetter Lieutenant 31 Rep 516 Posts Drives: hot rod Join Date: May 2009 Location: at the beach iTrader: (10)	question for those w/ DPs and misfires - suspecting O2 sims i've been getting misfires and 1/2 engine limp lately, mostly in morning when cold, sometimes when crusing just on/off throttle. i have a jb3 w/ O2 sims for my catless DPs. just cleaned intake valves (34k on clock and they were filthy btw), replaced all plugs, dealer just replaced hpfp and injector #6. 2 days after i got misfires on 4 5 & 6 again, but goes away after warm-up. i didn't save the codes but they were the same as i had before above work, pre and post lambda sensors. my question is do i just need to tweak my O2 sims if this is only happening cold or cruising on/off throttle? i've adjusted a few times but i've been getting codes either way - been a pita to be honest, to the point where i want to put my stock DPs back on. car ran great before them. anyone else have a similar issue?? __________________ 07 e90 335i 13 mk6 GTI 13 f30 335i
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06-28-2011, 03:32 PM	#2
bryce Banned 110 Rep 3,177 Posts Drives: zhp 3-pedal Join Date: May 2010 Location: texas iTrader: (22) Garage List 2005 bmw 330ci zhp [7.34] 2008 bmw 135i- sold [6.00] 2007 bmw 335i- sold [7.14]	all the bms o2 sim does is alter the signal from the secondary o2 sensors, to make it seem like there are cats still in place. pretty unlikely that the o2 sims are causing your misfires. it could be that the primary o2 sensor on bank 2 was damaged during the dp install, however.
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06-28-2011, 08:35 PM	#3
onefastman Major General 160 Rep 5,689 Posts Drives: 2009 135i 2011 e92m dct Join Date: Sep 2009 Location: Earth iTrader: (15)	What if it's just on cylinder 5 even after I change my plugs and switch around the coils? __________________ Legal Disclaimer: Anything I or anyone else says about my vehicle on this website(1addicts.com or any affiliated or nonaffiliated sites), pertaining to modifications, is only to gain acceptance from my/our peers, and does not actually represent anything actually existing on my car, and thus, cannot be held against me in any issues, i.e. warranty claims, that may arise.
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06-29-2011, 12:34 PM	#4
2wheelsrbetter Lieutenant 31 Rep 516 Posts Drives: hot rod Join Date: May 2009 Location: at the beach iTrader: (10)	right but if i turn the O2 sim up or down too much the ecu would adjust with more or less fuel no? based on the before/after cat reading. i thought maybe the sensor was damaged on instal, but i was REAL careful with them. also thinking it wouldn't be intermittent if something was damaged. so it did it again this morning, i haven't pulled codes yet, just shut down and restarted. 10 sec in when start-up idle starts to drop, it goes real rough and then into limp. reason i'm thinking it's sim related is that cyl 6 is still misfiring, after a new injector, new hpfp, new software, changing coil packs (coil pack is simply the plastic piece on the plug right?). i haven't reset all adaptations, but i thought with getting new software from bmw that wouldn't be necessary. might try that tonight. thoughts?? __________________ 07 e90 335i 13 mk6 GTI 13 f30 335i
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