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Discussion Starter #1 (Edited)
Hi:all
As shown in pic .
Pic 1. When we disconnect all o2 post and pre car run good
Pic 2 .when we connect all o2 post and pre car run bad
Car stock no tune on it
Car 2000 with 168000 miles.
All part changed .
Only these code .
Mechanic head flipped around can not figure it out.
All O2 post and pre Bosch brand not genuine
Ps : what is first code about switch chain
Help please
 

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See this thread about your switch chain question -
fault code 80 "Switch Chain, Frictional Connection
Just a thought- Make sure O2 sensors are being plugged back in on the correct sides. There’s several threads around here where guys have crossed them up, which leads to a rough idle.
 

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Discussion Starter #3
Thank you .
Any more guidance.

Thank you.
 

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Discussion Starter #5
Hi..sailor
Yes,, we did not unplug maf’s yet.
But when we bought the car all o2 were disconnected post and pre.
Now when Put new o2’s in,,car idle rough and there is strong fuel smell like it running too much rich .
Is mafs has to do something with this behaviour,,is it what is making car throughing o2’s code.
The wired thing when disconnecting all o2’s car run fine but still there is fuel smell but not as bad as it when o2’s connected.
As I said before mafs and o2 not genuine,,there are Bosch brand and price difference is a huge between them .
I do not think the code 50 has to something with this issues ,, is’n it?
Only these codes as showed nothing else’s .
Any help here what to do ?

Thank you.
 

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Hi..sailor
Yes,, we did not unplug maf’s yet.
But when we bought the car all o2 were disconnected post and pre.
Now when Put new o2’s in,,car idle rough and there is strong fuel smell like it running too much rich .
Is mafs has to do something with this behaviour,,is it what is making car throughing o2’s code.
The wired thing when disconnecting all o2’s car run fine but still there is fuel smell but not as bad as it when o2’s connected.
As I said before mafs and o2 not genuine,,there are Bosch brand and price difference is a huge between them .
I do not think the code 50 has to something with this issues ,, is’n it?
Only these codes as showed nothing else’s .
Any help here what to do ?

Thank you.
The maf test is just a test. If the car changes behavior then it might lead to another test, ETC. Both your sets of codes are telling. My best guess is the wiring to the O2s has been messed with and is wrong. If the O2s are unplugged you get the heater codes so that is correct.
When they are plugged in it says that the DME can't adjust the trims within the range it needs to. If it is not bad wiring then something in the fuel adjustment is off. Could be MAFs, could be the ICV or maybe even the injectors, a big air leak. Unplugging the MAFs will give us a hint of where to look.
When you unplug them let it run for a bit to adapt and after it has run to warmed up clear the codes and see if the codes come back and how fast they come back.
 

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Discussion Starter #7
Icv is new,, injector we did clean them.
Bad o2 connection maybe ,
Air leak maybe why not .
Will see tomorrow’s.

Thank you.
 

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Check the fuses in the DME box too. There's a brown-ish box with 5 30A fuses, in the middle behind the DME. At least one of those is tied into the O2 sensors. I'd have to look at WDS to figure out which one(s) it is, but I'm not near my laptop at the moment...
 

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Discussion Starter #9
Check the fuses in the DME box too. There's a brown-ish box with 5 30A fuses, in the middle behind the DME. At least one of those is tied into the O2 sensors. I'd have to look at WDS to figure out which one(s) it is, but I'm not near my laptop at the moment...
Thank you.
Please let me know which one ,,so I can check it.

Thanks.
 

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Discussion Starter #11
Will update this week what happened

Thank you
 

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Discussion Starter #12
Update:where do I start,,ok
1. Putting new o2s post and pre and new mafs car start roughy idle codes the same 50,,90,,91 car not shutting down while operating but rough idle no check lights at all only these 3 codes.
2. We put back old mafs and old o2s car start smother no rough idle but car stall within two minutes it was not doing this with the new o2s and mafs .
3. There is a leak in bank 1 passenger side
4. We check fusses in dme all good ( ( 30 amp each) 5 of them
o2s Post and pre bangs we will weld later but do not know if this will make car behave better .
There no code for misfire on any cylinder through the diagnostics.
Conclusion is when we put old or new o2s and mafs it is the same codes repeat it self
Except with new car rough idle .
With olds car smoothbut shut down within 2 minute by it self .
Is the 50 code has to something with this issue ( 50 switch chain ) do not know .
Any help we run out of idea.
I really need help here.
It is very annoying.

Thank you.
 

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The 50 code doesn't have anything to do with this, you probably have a 540i transmission in the car. Not a big deal, since it's the same as the M5 (Getrag 420G) but the cruise control switch location is different between the two. If your cruise control doesn't work, that's probably why...

If you have cracks around the O2 bungs, yes that's a problem as you're introducing extra air and that will mess up the fueling. I'd smoke test the top end too...
 

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50 is the clutch switch it allows the starter to engage but should not have any effect on a running car. Again what happens when you simply unplug the MAFs?
 

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Discussion Starter #15
Hi sailor ,, we did not unplug Mafs yet.
We thought to try switching to old o2s and old mafs to see what happen ,,at first no code then after car get warmed it thought the codes.
As I said there is leak on bank 1 o2s bung.
We see tomorrow’s after we weld the bungs.
But why it is shutting down with old o2s and mafs ?
It was not doing this with new o2s and mafs.
Also we will put car in ista tomorrow to see what gives.

Thank you
 

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Discussion Starter #16
The 50 code doesn't have anything to do with this, you probably have a 540i transmission in the car. Not a big deal, since it's the same as the M5 (Getrag 420G) but the cruise control switch location is different between the two. If your cruise control doesn't work, that's probably why...

If you have cracks around the O2 bungs, yes that's a problem as you're introducing extra air and that will mess up the fueling. I'd smoke test the top end too...
Yes ,, we will weld places and see what happen tomorrow’s

Thank you.
 

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But why it is shutting down with old o2s and mafs ?
It was not doing this with new o2s and mafs.
Adaptions and different readings from the different devices. It might be close to shutting down with the set that does not shut down but the readings are just a tad bit different so it does not. When it shuts down does it sputter or just turn off.
I take it you can't drive it around the block?
The thing is when you do stuff like you are doing the car is trying to run on the adaptions from the last set of sensors, it really needs a chance to adapt to the new sensor readings.
BTW that is not a good way to test things one sensor at a time is much better. You make too many changes when you change whole groups of things. A pair of O2s is fine, but not MAFs and O2s at the same time because they depend on each other and one will change the others readings.
 

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Discussion Starter #18 (Edited)
Thank you ,, no it does not sputter it just turn off.
Will put new o2s and mafs back tomorrow and try to drive it .
Will update tomorrow’s when we weld o2s bungs.

Thank you.
 

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But do those changes one at a time so you can see any differences. I would change the O2s start the car see how it behaves. Then just unplug MAFs see how it behaves. Next put the new MAFs in and see. Driving each time the longer is better but at least 10mins or until the car stablizes or stops changing.
 

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Discussion Starter #20
Ok sailor will do that tomorrow.
I think I am near to find the issues ,,I feel it.

Thanks.
 
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