Running rough, codes P0367, P0393, P0300, P0305, P0304, and P0308?

2008 BMW 750LI
116,000 MILES • V8 • 2WD • AUTOMATIC
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SAM CRENSHAW
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This is a purchase, so I don't know the history of the vehicle.

I'm not a mechanic, but I have some basic knowledge. I want to diagnose and repair this problem myself and can follow directions, even if I need to ask clarifying questions. I'm not afraid to put the elbow grease in but please bear in mind that I do not have access to expensive diagnostic equipment or dealer software.

Here are the current error codes I'm getting:

P0367
P0393
P0300
P0305
P0304
P0308

These codes have changed over time as I've done various things in trying to fix the problem. Here is a list of what I've done thus far:

-Replaced two camshaft position sensors (although I can't swear on a bible that I replaced the right ones, as I couldn't get a clear explanation at the time of which ones needed to be replaced)
-Sent off the DME for testing. It came back with a clean bill of health. Absolutely no problems with the DME.
-Tested the plugs to all four camshaft position sensors. (they're all getting juice)
-Replaced all spark plugs and one ignition coil that I broke trying to remove

It's running rougher than ever and is struggling to start.

What's my next step? Thank you.
Sep 23, 2022 at 9:13 AM
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STRAILER
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The P0367 code is an incorrect reading from camshaft sensor “B” located in engine bank 1 that is too low, which means the sensor can be out or the actuator is not working. First make sure the engine oil is clean and full, next remove the spark plugs and replace them with new ones, OEM only. The other codes are random and specific misfire codes, which should be cleared once the sensor and plugs are replaced. Sensor B is the exhaust sensor on the passenger side of the engine.

Here is a generic guide to help you with the spark plug replacement and instructions for your car in the images below.

https://www.2carpros.com/articles/how-to-change-spark-plugs

Check out the images (below). Please let us know what you find. We are interested to see what it is.

Sep 23, 2022 at 1:27 PM
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SAM CRENSHAW
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Thanks so much for your answer.

The engine oil is good.

I pulled the plugs and I'm trying to find out what is the OEM plug that I need to get. 7 of the plugs were Bosch and one was NGK. It wouldn't surprise me if these were the original plugs as they were nasty as hell. (Pictures attached). I'd like your confirmation, but I think the OEM is the Bosch ones as they also say BMW on the plug as you'll see in the photos.

Can you tell me exactly what plugs I need to get?

Thank you so much.
Sep 25, 2022 at 7:49 AM
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SAM CRENSHAW
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Bosch FR7KPP332???
Sep 25, 2022 at 8:17 AM
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SAM CRENSHAW
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I replaced the plugs with OEM, but now the car won't start. It started once but stopped after only a second or two and hasn't started again. It turns over as normal but won't run.

The current codes are p0367 and p0393 along with some misfires.

A couple of notes:

My error codes have changed with the different repairs I've attempted, and the misfires vary, and have been combinations of all the cylinders.

The main error codes have always been two:

1) Either p0365, 367 or 368 (sensor b, bank 1), but never more than one of those at a time,

and,

2) either p0391 or 393 (sensor b, bank 2), but again, only 391 or 393, never both at the same time.

I'm assuming that the sensor errors are what causes the various misfires, and that the problem is not the misfire itself.

As I said in the beginning, I'm not a mechanic and don't know some of the auto mechanic basics.

It is altogether possible that in the beginning, due to a lack of knowledge, I could have mistakenly replaced the wrong sensors. I believe there are four of them on this vehicle, right?

When I first began this project, I was getting one code, p0391, along with misfires on cylinders 1 and 2. It's never been that good again.

There have also been a couple of times that the battery has drained and I've had to recharge it, as well as being disconnected for a few days at a time, if that could cause a need for me to have to reset something of which I'm unaware.

I'm ready for the next diagnostic step if you can point me in the right direction.

Thank you so much,

Sam Crenshaw
Oct 17, 2022 at 11:23 AM
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STRAILER
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I think the best bet is to send me a video of the engine cranking over so I can see if the engine is in good condition or was can do a compression test. Here is a guide to help you can get a compression gauge at the autoparts store and rent it for free or cheap.

https://www.2carpros.com/articles/how-to-test-engine-compression

Let us know what happens and please upload pictures or videos of the problem.
Oct 18, 2022 at 10:17 AM
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SAM CRENSHAW
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I did a compression check while I had the plugs pulled. Here were the results:

Cyl #
1 - 132
2 - 115
3 - 137
4 - 110
5 - 122
6 - 130
7 - 135
8 - 110
Oct 18, 2022 at 10:47 AM
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SAM CRENSHAW
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Correction cylinder was 120.
Oct 18, 2022 at 10:47 AM
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SAM CRENSHAW
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I managed to get it started briefly again this afternoon but as before it only ran for a few seconds before choking down.
Oct 18, 2022 at 4:20 PM
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STRAILER
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It sounds like the exhaust could be clogged due to a bad catalytic converter or a weak fuel pump, when the engine stops running with it run on starting fluid?
Oct 19, 2022 at 12:25 PM
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SAM CRENSHAW
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Did you mean 'will' it run on starting fluid?

Meaning I should try spraying some in the carb and see if it starts up?
Oct 19, 2022 at 12:27 PM
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STRAILER
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yes, spray it into the air intake to see if it runs at all. Let me know.
Oct 20, 2022 at 11:19 AM
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SAM CRENSHAW
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Wouldn't start. So now we move on to the catalytic converter?
Oct 22, 2022 at 10:40 AM
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STRAILER
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Yep, this will be the next step this guide can help. Remove the exhaust from the cats or you can try to remove the primary oxygen sensors.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please go over this guide and report back.

Oct 22, 2022 at 1:25 PM