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BMW 530i 2001- cylinder 1 2 3 misfiring. Please help!

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misfire o2 sensor
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27K views 16 replies 5 participants last post by  Swat17  
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#1 ·
When I bought the car it had a very rough idle and it woud stall.
So I did some research on the forum and found it to be the ICV. So I replaced it and my stalls went away.but my car still idles rough, but doesn't stall atleast. I checked the codes and it said cylinder one two and three misfiring with fuel cutoff, o2 sensor bank 1 sensor 1 bad ckt. So far I've replaced my vanos seals,intake and exhaust cps, bank1 o2 sensor.I've cleaned my disa valve and replaced my head gasket. I replaced all 6 sparkplus to nkg platinum. And I tested my coils and they all work. I need help big time. I don't know what I should do next.
 
#3 ·
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#9 ·
I was hearing a clicking noise in that area so I did some research about it. It turned out to be related to the icv, also others have had the same problem. So I checked it out and it had alot of buildup inside it. Tried cleaning with carb cleaner. Didn't help so I just replaced it. After that my stalls whent away, except my rough idle/misfire
 
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#4 ·
Well first--you replaced your head gasket or valve cover gasket--which is it--you should start by moving the coils from the three cylinders that are missing to the other three that aren't to see if the miss moves--bet they don't and I think you have a large vacuum leak and thats causing your problem--you have to have the codes reset to turn the fuel back onto the engine for the affected cylinders--lets start there--if by chance you have indeed had your head gasket replaced we need to look at a few other things
 
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#5 ·
After looking at this again you stated that you replaced the Vanos seals--I think you have an air leak and it's coming from the CCV valve and one or more of the 4 hose's that hook up to it--probably was aggravated
and made worse when you changed out the valve cover and again when you replaced the Vanos seals--also when replacing the valve cover--did you purchase the 15 rubber bolt grommets that are needed to do that job correctly?
 
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#10 ·
i have checked my ccv hoses and found the hose with the red arrow extremely pinched. it was not cracked. i replaced that hose and the one that goes from the valve cover too just incase. now when the cars rpm gets low i hear a loud knock in the engine. when i rev up the engine, after a few seconds the rpm's start dropping by themselves, and then it knocks again. before replacing my vaccum hoses the car still made the knocking noise, but now it worse.
 

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#6 ·
If his replacement set was missing 2-4 rubber bolt grommets; where can he get the additional ones?
 
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#7 · (Edited)
Think EACTuning might have those available, that would only have a small air leak problem--thniking that the CCV valve's main hose from the valve cover down to the ccv is the culprit here--thats the first one to go in most cases because it gets handled alot and becomes brittle faster--also I think it's thinner plastic.
 
#8 ·
Try looking further upstream like the MAF. Take it off and clean it and then reinstall making sure all connections are good. Also, as mentioned in a previous post, check all of your vacuum hoses well. This is what will cause your car to run lean at first and then the ECU will cause the engine to run rich as a result in the closed loop operation lean signal feedback. It would not hurt to run a good quality fuel system cleaner for the injectors.

If you have a rich condition as a result of a dirty MAF or unmetered air, then it will easily gunk up the ICV with carbon and make it stick as well as cause poor detonation. Rarely does the ICV go bad - just a good cleaning will allow the valve to move freely. That said, the rich condition gets to your exhaust and goes unburned laying a nice coat of soot on your O2 sensors and on to your cats - not good.

Also, do a hard reset by disconnecting your battery terminals and connecting the with a bridge for 10 minutes.
 
#12 ·
mmm635 said:
a dirty MAF ... will easily gunk up the ICV ...laying a ... coat of soot on your O2 sensors
Click to expand...
Hi Michel,
Even though I know nothing about misfires, I've just now added this advice to the general debugging procedure to follow to isolate the cause of an E39 misfire.
- General diagnostic procedure for a single or multi-cylinder E39 intermittent misfire?

Please check it out for accuracy! Thanks.

mmm635 said:
do a hard reset by disconnecting your battery terminals and connecting the with a bridge for 10 minutes.
Click to expand...
OK. I added this. Easy enough to do. But is this a hail mary play?
Do you really believe this will do anything useful?
What?
 
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#11 ·
I would replace the entire CCV valve and the hose's--sounds like the CCV is getting ready to go out--don't know how you replaced the hoses without cracking others--cylinders 1 -2 -3 would be the first to gain air from a vac leak coming from the CCV valve.
 
#14 ·
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#15 ·
Ok i changed my ccv and all hoses. I don't think I have a vacuum leek anymore. One thing I noticed is that if Either one of my cps sensors are disconnected (intake or exhaust) the car seems to be idling smooth. Why is that? -- ( I replaced both of them with the original OEM)
 
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#16 ·
Well lets look back behind the intake on hte drivers side--you will need to remove the cabin air ducts and have a small mirror and a flashlight--check back behind the intake with the mirror and there should be two hose's back there--if they have never been replaced--bet you have another vac leak there ---
 
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#17 ·
Its been a while and i still cant fix the car. I have been waiting for a while and got my ECU replaced. It got rid of all my misfires on cylinder 1 2 and 3. But, my PreCat O2 Bank1Sensor1 code doesn't wanna go away (car idles a little rough too). I'm 100% sure i don't have a vac leek anymore because a mechanic did a smoke down test and found nothing except for my oil tube gasket which got fixed. Please help me, i don't want to give up although i think its impossible. what could be causing this?
 
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