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Discussion Starter #1
Hi guys, I've been a longtime lurker but never joined. I've got an 00 M5 that has thrown some codes recently:

P0301
P0306
P0300
P1342
P1345
P1353
P1343

I've done some research and the top 3 codes are related to misfires, but the other 4 mixed with those are puzzling me as to what the actual issue might be.

Any thoughts of where to start?

Thanks
 

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Company Representative for Valley Motorwerks
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How does the car run? - codes don't really mean anything unless you get the frequency along with the recorded problem. If they only occurred once and the car otherwise runs fine clear them and be about your business.
 

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Discussion Starter #3
Good points that I meant to add.

I pulled the codes and they come back very quickly after being cleared.

The car has some loss of power, but nothing else noticeable. Mechanic even thought it was actually driving fine, but I can tell there is some loss of power.
 

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Company Representative for Valley Motorwerks
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Good points that I meant to add.

I pulled the codes and they come back very quickly after being cleared.

The car has some loss of power, but nothing else noticeable. Mechanic even thought it was actually driving fine, but I can tell there is some loss of power.
Does your mechanic have a way of looking at adaption and smooth running values? If not find another with the right diag tools. Too many variables involved - how old are the plugs, do you have oil in your intake tracts, any vacuum leaks etc etc etc.
 

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Can you post the definitions you have for those codes or translate them to their hex equivalent. Please.
Have you cleared your codes and seen what came back?
 

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Discussion Starter #6
I'm not sure my mechanic has a way to look at adaption and smooth running values. He is running it over to another mechanic that is setup more for diagnostic tools of BMWs.


Off the top of my head, here are the definitions I recall:

P0301 - misfire cylinder 1
P0306 - misfire cylinder 6
P0300 - misfire on multiple cylinder
P1342 - Misfire During Start Cylinder 1
P1345 - Misfire cylinder 2 with fuel cut-off
P1353 - Misfire Cylinder 6 With Fuel Cut-off
P1343 - Misfire cylinder 1 with fuel cut-off

Cleared codes and the same ones come back.
 

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Leaking injectors, I will look up the codes but that is what the best first guess is. Have you ever put injection cleaner thru your car?
 

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I read my description of the codes. The ones I am keying on are the 1340 ones. Basically it says that the engine is firing when it should not, during deceleration. The gas is suppose to be zero when you decelerate in gear. The misfire code is that the knock sensor is registering a noise and the misfire monitor is not seeing a deceleration as it expects. The only way I can see that happening is if the injectors are not closing correctly. Dirty would be the likely cause although some strange unregistered electrical fault could do it too.

If your mechanic put a gauge on the fuel system and charged it then pinched the line from the tank and the line returning to the tank from the filter, the gauge should not drop pressure. If the pressure drops it is non closing injectors. Injectors could be attempted to be cleaned by adding injection cleaner to the fuel tank or they could be pulled out and sent to a facility for cleaning. Your mechanic should be able to figure that out.
 
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