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

[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.

[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]

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!

[pshovest]

I'd forget the smoke test. If you had a vacuum leak or other intake issue causing intake air to bypass the MAF, the car would run better with MAF disconnected.

[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.

[jfoj]

Most of the bad fuel these days has too much Ethanol in it. But like anything, "The solution to pollution is dilution". 1 decent fill up should sort any fuel related problem for the most part.

Did the vehicle go through a car wash before any of this happened?

The issue with the water leaking may not specifically be with the 6 cylinder gasoline engines, but I know it can and does cause problems with the 6 cylinder Diesels as I recall.

The water does not leak right at the base of the windshield, it actually leaks right at the back edge of the hood, right around cylinder 4 or 5 as I recall.

Good luck, this should not be so difficult, but it will be interesting to see what in the end was the primary problem.

[X5Cat]

In the case of my Chevy, the fuel distributor recommended draining & replacing the fuel, with a bottle of Techron added. That was all fine except that the mechanical damage had been done, and it happened in a short time. Just a coincidence that it was the same big-name brand gasoline distributor then as it is for the station where my wife filled up the X, a couple of hours before this all started. Just sayin' -- don't know yet where this will end up.

[ard]

When something 'breaks' on a car, it is fine one day, then - in a moment- something happens and you get a miss, a CEL, whatever.

There is almost certainly SOMETHING that occurred at that time... "I turned right". "I passed an AM/PM market"..."The cell phone JUST rang"...or "I filled up the tank one hour before (or 30 minutes or the day before)".

These are usually not causal events.

In a million plus miles of driving I have never had 'bad gas' that caused a CEL.