idling problems/misfire sound !please help - BMW Forum

mhbmw328i · 09-19-2008, 10:32 PM

i have a 98 bmw 328i have just recently been having problems with. i was getting onto the turnpike not going to lie i had it WOT got up to speed shifted to 5th cruised everything seemed fine until i got off the exit and the car started idling erratically and was making a choppy sound or misfire sound to about 3k rpm then above that seems to be fine. Anyway i began to try to diagnose the problem took it home did a compression test to see and everything seemed to be fine there. then i move on to getting hooked onto a dtc scanner no misfire code only code was o2 sensor bank 2. didnt think that o2 would be the cause of this problem i proceeded and checked all my plugs which were only about 2months old everything seemed fine. then i proceeded to look for a vacum leak ended up taking the intake manifold of to check them all no signs of a leak anywere. fuel filters new the air filters new could this be a rod bearing?? but its not really a loud knocking sound more like a cammed subaru boxter engine sound lol til 3k if you know what i mean. anyone know?

chinonca · 09-19-2008, 10:39 PM

How many miles you have on her??

thekid · 09-19-2008, 10:58 PM

O2 sensor could be the problem. It could be misreporting under 3k which could basically lean out the car to the point of running rough. Lets try replacing it and then run it see if there are still problems and then rescan. The O2 sensors on these cars can cause real havoc on them. Mine kicks a check engine light if I maintain 3k rpms, luckily I've not had any other ill effects form it.

mhbmw328i · 09-20-2008, 10:31 PM

it has 138,000 miles and i was planning on replacing the o2 but i mean this is the third one i replaced on this car and when the others didnt effect much. but ill try that thank you. also it seemed to be running better today like it has a mind of its own kinda wierd. so being that its getting better im going to have to say its def not something internal

chinonca · 09-21-2008, 01:15 PM

Quote:

Originally Posted by mhbmw328i

it has 138,000 miles and i was planning on replacing the o2 but i mean this is the third one i replaced on this car and when the others didnt effect much. but ill try that thank you. also it seemed to be running better today like it has a mind of its own kinda wierd. so being that its getting better im going to have to say its def not something internal

Try putting a can of sea foam thru the fuel system!

mhbmw328i · 09-21-2008, 07:13 PM

actually i did i sea foamed the motor and fuel system about 4 months ago and it has a new fuel filter im waiting for my o2 sensor to come in i think that should fix the problem because its not consistant but thanks for all the help

bavarian · 10-04-2008, 04:21 PM

hi,try checking the idle valve,take it out and clean it with carb cleaner and refit try again if not it might need replacing.