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Old 03-01-2015, 11:45 PM   #1
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Join Date: Mar 2015
Location: Minnesota
Posts: 4
My Ride: 2002 330 Xi

I have had this dreaded code for awhile now.

I unplug my MAF and car runs on all 6 with plenty of power but still rough idle.

I have changed my DISA and performed a smoke test. I found 1 broken vacuum line from the secondary air pump.

I have checked the ccv oil line to dipstick, still looks brand new and is flexible.

I have replaced my lower intake boot.

Swapped coils/plugs... does not change cylinder.

I found that my power booster hose where it connects above intake came apart, I need to get this new connection, but I epoxied it together and used silicone to seal it... no leak (tested with starting fluid while car is running).

my stft b1 was 16.4
my stft b2 .8
both downstream 99.2

that is just one snapshot, they all seem to swing okay.

I am at a loss. All my ccv hoses appear to be newer... I have sprayed the car with starting fluid on all the connections and not heard the slightest change.

If I clear the code, I can rev the car with low to no load and not trip the code (in park or on snow/ice) as soon as there is a load the code trips.

The only exception to this if I floor the car on the highway as it clears and I stay in the high rpm range, more often than not, it wont come on til I back off the throttle.

This all started flooring the car a few months back, and as I have time to play with it, I do. Weird is that it was almost like I ran over something (though I didn't) my inner fender in front of drivers tire came loose just so the front hung down enough to allow the external temp sensor fell and dragged on the ground at the EXACT time this happened.

All my hoses are still flexible and all appear new. Like I said, new DISA, Secondary air pump a few months back, all new plugs, 3 new coils, I have tried different octanes and not a hint of difference.

I am at a loss at this point without ripping intake off and just replacing every hose, seal, o ring, and ccv.
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Old 03-02-2015, 02:01 PM   #2
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Join Date: Aug 2009
Location: gross deutsches reich USA
Posts: 958
My Ride: 323i with S54
change the MAF then
Siemens MS43 tuning master
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Old 03-02-2015, 04:16 PM   #3
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Join Date: Mar 2015
Location: Minnesota
Posts: 4
My Ride: 2002 330 Xi
I missed that I changed the MAF... The rough idle is the same with or without the MAF plugged in, therefore, I feel that somehow I have a leak that I cannot find. With the MAF plugged in, once I get the car to temperature, I can clear the code long enough to see both o2 sensors are swinging, at higher rpm, bank 2 has between 2 and 5% higher value, but near idle, they will bounce between -1 and 2.. almost always bank 2 is slightly higher, but not much.

The only advantage I have by unplugging the MAF is no fuel cutoff to cylinder 4 so I have full 6 cylinders for driving in traffic. Gas mileage difference is negligible. I get 25 mpg hwy with it plugged in, and 22.5 without it plugged in.

I have been reading virtually every post for this code. I am thinking at this point after writing my original post, that I need to replace the intake gasket, fuel injector and vanos o rings, and anything I stumble upon in the process. The leak is slight, but it only seems to hit cylinder 4, the only other thing I could try is swapping injectors to see if it follows the injector, if my injector got slightly plugged. I am open to any other suggestions.

The only other thing I kinda noticed, if I unplug the DISA and run it, the CEL takes a little longer to kick on. I think this is just how it routes air through the intake, but I figured it may be worth mentioning.

I have taken this car from a scary ride with all sorts of k bus issues including the trifecta abs/dsc lights, drive train issues when I bought it a year ago, and had it running perfect for about two months before this happened. Been a slow process with much learning and reading.
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Old 03-02-2015, 04:25 PM   #4
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Join Date: Nov 2009
Location: Fairfax, VA USA
Posts: 22,861
My Ride: 330CiC, M5, X5, E93
You cannot find vacuum leaks on these engines with spray, all the leaks are on the bottom of the hoses.

Search YouTube for Scotty Smoke Test. Do what Scotty does or build a smoke tester from a related video. Need to smoke the intake and make sure the crankcase fills with smoke as well, usually remove the oil fill cap for smoke to come out, then recap crankcase.

Assume you have seen the first link below in my signature.

Need to also read this thread - http://forum.e46fanatics.com/showthread.php?t=1057387

The CCV lower oil return hose is usually covered with a braided mesh and the collapsed portion is hard to see.

If the CCV and hoses are original, they NEED to be replaced. If the intake boots are orignal, they NEED to be replaced.

Need to see warm idle and steady highway cruise Fuel Trim info along with any Freeze Frame data.

Do not replace the MAF at this point.

You may need to perform a compression and cylinder leakdown test if you cannot find any vacuum leaks, but vacuum leaks are the most common problem on these cars.
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 03-02-2015, 04:43 PM   #5
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Join Date: Mar 2015
Location: Minnesota
Posts: 4
My Ride: 2002 330 Xi
Thanks, I will try the further smoke test. I thought about the booster but I never tested it, I cannot hear any noise from it, and the idle does not change or fluctuate with braking or not, I will try to plug it and test for a code.

I have read all your links, in fact, I ran down your list for them. my intake boots are new now. The CCV hoses all look newer. The lower one to the dipstick was fine. still flexible and in fact looked almost new.

The MAF is new a few months before this, because it did go out. I highly doubt that the MAF has anything to do with the problem. Unplugging the MAF was to see if default trims still caused the misfire. All unplugging has told me that either I am getting unmetered air, or I am not getting enough fuel into #4 cylinder to burn properly (which also could be a compression issue, I attempted to test the compression the day it happened but my tester crapped out on me) but the fact that the cylinder will burn and not miss with default values leads me to suspect compression most likely isn't the issue
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Old 03-02-2015, 04:50 PM   #6
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Join Date: Mar 2015
Location: Minnesota
Posts: 4
My Ride: 2002 330 Xi
Oh and the broken line I did find as I said before was for the secondary air pump, and on cold days it would barely idle at first start up. That is resolved and at 0F this morning car started and idled like it does any time.

The IAC valve offshoot of the lower boot did have a crack, and that boot was replaced.

These cars are tough to find the minor leaks because everything is so well hidden. Will take me a few days til it warms up to do any further troubleshooting.
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p1349, rough idle

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