P0300, P0302, P0304, P0306, Engine running rough with little power

[jfoj]

The typical OBDII DTC or trouble code is a single Letter followed by 4 numbers. Example PXXXX where X is a number between 0-9.

The few times I have seen DTC's or Trouble Codes with a 2nd letter the letter seems to be in the last character position and tends to appear to be a Hex value A-F. I have seen this before mainly on some BMW's. Unclear if this is the way BMW has presented the value or if this is a Manufacturer Proprietary code that comes through as a generic code but in the wrong format??

Anyway the majority of these codes I have run into on BMW have to do with the MAF. It is pretty obvious that the MAF on your vehicle is not responding.

I do not know the N52 like I know the M54 engine. However, I assume the MAF on your vehicle is a typical modern MAF that has both the IAT (Intake Air Temperature) sensor and MAF all integrated into one assembly. Most of this design MAF has 5 wires or connections, sometimes the actual connector may have 6 cavities, but only 5 connection are used.

I do not have the connections committed to memory and your engine may be different. I recall there is a 12 Volt switched feed and the other 4 connections make their way back to the DME.

You need to check for loose female terminals, power, broken wiring or continuity back to the DME connectors.

The MAF could just be bad a well, but this is an expensive test to rule out other problems.

You could try to source a used MAF on Ebay for cheap and hope it will allow you to determine if your MAF is actually bad or if you have a wiring problem. I would not buy a "new" cheap ebay MAF as most of these are Asian counterfeit units that do not work correctly. You will end up replacing any cheap ebay or parts store MAF with an OE supplier from a valid and known good parts vendor.

[pshovest]

Move coils 2,4,6 to cylinders 1,3,5. Do codes move?
Unplug MAF and start. Is performance any different?

[X5Cat]

Originally Posted by pshovest

Unplug MAF and start. Is performance any different?

Good, beautifully simple suggestion -- I'll do that, thanks.

[jfoj]

Do not expect miracles on this one, but you may find the MAF starts to report after unplugging and reconnecting, bad connection or broken wire.

But a this point the MAF is effectively disconnected because there are no MAF readings being picked up by the DME.

Also note the Freeze Frame data had Misfires for Cyl #4 & #6. These just so happen to be the 2 spark plugs that are not all carboned up. #4 & #6 appear Lean??

Rarely do ignition coils act up on cold start or idle, but they could. I would also think if #4 & #6 coil were having problems these plugs would appear to be a bit wet with fuel.

The STFT for Bank #1, Cylinder 1-3 is way Negative, trying to remove fuel due to a Rich condition which I agree with due to the spark plugs and the lack of a MAF reading.

The STFT for Bank #2, Cylinder 4-6 is way Positive, it is actually Maxed out at +30% at highway speeds. This tells me there is a Lean condition for Bank#2 which the spark plugs and STFT seems to agree with.

I am thinking you have some sort of crankcase air leak or a problem with a CCV hose as a guess??

I think it is time to think about Smoke testing for air leaks in the crankcase and/or intake path.

In case I did not link this previously, here is a simple Smoke Test below. The fluid transfer pump is about $10 and most Auto Parts stores and maybe even Walmart may carry it.

I am starting to think you have 3 very distinct problems.

1. Engine running too cool, probably a soft thermostat. I really do not think these engines are supposed to run a 175F/79C on the highway. I expect 205F/96C range, maybe just slightly higher. This may be due to no MAF signal and the DME commanding the thermostat heater on? You may try unplugging the thermostat heater connection and see what happens to the temperature. If it operates in the range I expect it to, then the thermostat is not actually bad but something may be commanding the thermostat heater on. This also assumes this engine has the electrically controlled thermostat which I believe it has.

2. No MAF reading. Not sure what to guess at here. Bad MAF or bad connections. But check fuses first.

3. Some sort of vacuum leak that is not in the main intake path, probably CCV or crackcase would be my first guess.

https://www.youtube.com/watch?v=AsgB9eBl58I

[X5Cat]

https://www.dropbox.com/s/2xfqksiq8g...23410.csv?dl=0

The above is a dropbox link to a new log I just ran, this time with the MAF actually plugged in!

Went out to try disconnecting it as pshovest suggested. When I touched the connector, if fell away loose! Plugged it back in and the dashboard started showing MAF readings. Guess it must have popped loose while I was changing plugs. Engine runs better than it did with the MAF unplugged, but the missing and shaking are still there.

At least this is one mystery out of the way.

[pshovest]

I believe these misfire codes will disable the fuel to the cylinder to prevent cat damage. Fuel trim and O2 sensor data is likely useless if cylinders are disabled and intake air is being pumped over the O2 sensors.

Post 41 shows 6.31 g/sec air flow, high for idle. Not sure why it's not in the logged data. It will be high if DME has disabled the misfiring cylinders and the remaining three have to overcome the drag of the disabled ones.

My coolant temp will drop to low 80's with aggressive driving. Disabled cylinders and resulting larger throttle opening may put the MAF into the range where the DME will lower coolant temp via MAP thermo. Low temp shouldn't cause misfires.

[pshovest]

Time to swap the coils

[X5Cat]

Originally Posted by pshovest

Time to swap the coils

With 2 cylinders starting to miss at the same time, and the "lean" look of the plugs, I really don't think swapping the coils is going to do it. But, I do know how strange things can happen. (And, I'll admit I also didn't think the MAF was disconnected.) I will swap them when I remove the cover for the smoke test. Thinking I need to go shopping for the pump and stuff to do that -- as soon as the wife dismisses me from hanging/illuminating more Christmas decorations outside. I may even consider a compression test while I'm back in there, although I would need some kind of extension tube to hook my gauge in to those deep plug wells.

jfoj: See any new revelations with the new log?

Thanks, guys!

[jfoj]

So here is what I do not get, 2 coils going bad at the same time, just usually does not happen. Maybe this is one of the water leak from the front cowl problems?? As I recall the water leak from the cowl may actually cause problems with the injectors connectors.

So while you are under there looking around, if you can easily disconnect the injector connector for #4 & #6, inspect the connector and injectors closely for corrosion and discoloration.

The problem may be injector wiring and not a coil problem, but I would hope there would be some other codes, but funny things happen at times

Also from the looks of the plugs, something has been going on for some time.

But it is Sunday afternoon and you can easily swap coils and see what happens.

Make sure you mark them so you can keep track of things.

As for the MAF reading, it is all good on OBDFusion, BUT, I think the MAF may be over reporting. We will need seeing the calculated engine load and the MAF reading at warm idle higher than I would expect.

Is the engine still missing and missing badly?

Another interesting things is now that the MAF is reconnected, the engine is barely running in Closed Loop, it is in Fuel System Status 4 most of the time for the Log.

I also need to see the Pre-cat Wideband O2 sensors. You do not have them Logging. They are much further down the in the List of things to Log.

Engine temperature is looking better this round of Logging as well.

[X5Cat]

Yes, the engine is still missing and missing badly. Too tired last night to swap coils around after the wife finished with me for Christmas decorating. I'll try to set up the logging for the after-cat O2 and maybe swap coils around tonight.

I'll look for injector wiring concerns while I am in there. I haven't seen any signs of water running down from the cowl, but hey, I don't want to rule out anything - unless I [I]can[I] rule it out. Remember the plugs were run like that for at least 3+ hours from Baton Rouge to the eastern shore of Mobile Bay, at highway speed, so that might have washed them clean & white.

I had a Chevy engine once which, along with many other vehicles in the area, got exposed to a tank of bad gas (confirmed by the supplier). It was a pushrod operated valve design. The bad fuel had a tar or gum forming tendency which created enough resistance that the pushrods bent inside the engine. Multiple valves then not opening, with "skips" or misfires. I don't know the insides of these engines but given the sudden onset of the problem it does make me wonder if something similar could have happened here.