NEED HELP: E46 Dies when MAF is plugged in & question on ICV Cleaning

[BMW325iE46]

I have a 2002 325i E46 that has been having problems with the engine stalling/dying. This started a couple of months ago where when the car was first started and driven, it would consistently die at the fist stop sign and then it would run fine for the rest of the trip.

Around a month or so ago, the frequency of engine dying increased to multiple times at stops.

The most recent codes that I was getting were:
P0172 System Too rich (Bank 1)
P0175 System Too Rich (Bank 2)

In addition to the above Too Rich codes, I previously also had:
P1085 Fuel Control limit mixture too lean Bank 2 Sensor 1
P1085 Fuel Control limit mixture too lean Bank 1 Sensor 1
P1346 Misfire during start Cyl 3
P1343 Misfire Cyl 1 with fuel cutoff

I suspected the MAF (Mass Air Flow Sensor) so removed it and cleaned it with CRC mass air flow sensor cleaner. After reinstalling the MAF, the car would instantly die after starting! I disconnected the MAF and the car started and ran fine! I did some test driving and it no longer died during stops any more.

I next had the lower intake boot replaced. The smaller line that goes to the ICV (Idle Control Valve) had around a 1/2" tear in it. I also bought a new MAF and installed it however the car still dies if the MAF is plugged in but runs great if it's unplugged.

From the Internet searching that I've done, it looks like the next step would be to check the ICV and clean it if needed. I watched a couple of videos on removing the ICV and it doesn't look too difficult, so I started the process. I got to the point where I got the 10mm nut and T40 bolts off, but decided to stop at that point due to uncertainty of reinstalling the ICV by being able to get the rubber boot reconnected to the intake manifold.

My questions at this point are: Based on the details that I've outlined, would checking the ICV be the next thing to do? If so, how difficult is it getting the
ICV rubber boot reconnected to the intake manifold? Is there anything else that I should check?

I appreciate all of the great information that this forum has provided to me and am looking forward to input from all of you that have been through this process before.


-TR

[MarcoZandrini]

That lower rubber intake boot is a bit of a pain to install. There’s a flap of rubber on the bottom end that’s the “guide” as to the proper orientation of the boot. Basically, the throttle body flange has 2 bars. One is at the 1 o’clock position and the other is at the 3 o’clock position, roughly. The boot’s flap has to go into the gap between the 2 bars. The first time you install the boot you’ll be wishing the allies had nuked Munich (/s). It’s an easy task with the engine out if the car but a real pain in the axx with the engine in the car. Also, the orientation of the 2 clamps will have you wishing that the allies had nuked all of Germany (/s)!
The first step is getting the clamps loosened. I doubt that the boot is the original so hopefully someone positioned the clamps so that they are accessible. On my old 330Ci I’d position the main clamp so that clamp’s screw mechanism was at the 12 o’clock position. That way I could reach it by inserting a long blade screwdriver at the front of the engine horizontally. As I remember the smaller clamp mechanism was positioned at the 3 o’clock position.

[BMW325iE46]

Marco,

Thank you for the reply. Sounds like a royal PITA for sure!


-TR

[BMW325iE46]

Here's an UPDATE with Good News so far:

I was not comfortable with what's involved with removing and reinstalling the ICV, so I called a local mechanic who said that he would be able to install a customer supplied replacement ICV and only charge for an hour of work ($120.00), so I figured I'd have him do the challenging work and proceeded to put things back together.


I went through the following steps to put the car back into service:

- Reconnected lower intake boot line to the ICV
- Reinstalled 2 x T40 bolts and 1 x 10 mm nut
- Sprayed CRC electrical cleaner on the ICV connectors and plugged in
- Cleaned DISA valve with paper towel
- Replaced DISA o-ring
- Reinstalled DISA valve, 2 x T40 bolts
- Cleaned DISA electrical connectors and plugged in
- Removed some rubber parts from air filter that were separated and wedged into area behind forward most left securing clamp
- Inserted original MAF into top half of airbox
- Connected upper intake boot to MAF
- Secured top half of airbox
- Cleaned MAF electrical connectors
- *** Reconnected MAF electrical connector ***

I started car expecting it to instantly die since the MAF was reconnected, however it ran fine with the MAF connected! I did a test drive and it ran great. There were no engine stalls or dying at all.

I'm not sure what corrected the issue - I'm hoping cleaning the electrical contacts or perhaps something else that I did during the work was responsible, but I'm very optimistic at this point. Now I just need to do some driving to get the monitors set so I can get the smog check done.

Any thoughts on what might have happened are definitely appreciated!


-TR

[shadowpuck]

what codes do you still have?

i have to admit i didn't find it particularly difficult getting the ICV out and cleaning it - but, there's things i find challenging and others find easy - so, there you go.

general maintenance items might likely apply here - how old are the o2 sensors, how old are the spark plugs and are they the correct ones for the car.....

[BMW325iE46]

Shadowpuck,

Glad to hear you had a good experience with the ICV.

No codes were showing up at the time that I wrote the update on Wednesday. I need to get the car smog tested so I had to do some driving to get the OBD II monitors completed, which I did a little while ago and unfortunately got some pending codes. I'll do another update with details along with the pending codes that came up tomorrow.



-TR

[BMW325iE46]

The two pending codes that I had were:
P0172-PENDING System Too Rich (Bank 1)
P0175-PENDING System Too Rich (Bank 2)

After my next trip, they cleared, the CEL never came on at all.
The 2A and OH monitors are still showing incomplete. All of the other monitors are okay.
I ended up getting a scanner that can show Live Data. Here is a set that I got from a drive earlier today.

FRAME MPH RPM DTC_CNT LOAD ECT S-FT1 L-FT1 S-FT2 L-FT2 S-Adv IAT MAF TP AIR_ST O2-11 S-FT11 O2-12 S-FT12 O2-21 S-FT21 O2-22 S-FT22 Fuel-A Fuel-B
1 0.00 621.00 0 12.9 197.60 -2.3 7.8 -1.6 7.8 3.5 91.40 0.01 0.0 OFF 0.575 -4.7 0.795 99.2 0.195 -0.8 0.795 99.2 CL CL
2 14.29 1183.00 0 7.1 197.60 -3.1 7.8 -4.7 7.8 1.5 93.20 0.01 0.0 OFF 0.695 -24.2 0.865 99.2 0.185 -24.2 0.865 99.2 CL CL
3 22.37 2784.00 0 7.8 192.20 -25.0 7.8 -22.7 7.8 12.5 89.60 0.01 0.0 OFF 0.795 -2.3 0.965 99.2 0.815 -7.0 0.945 99.2 CL CL
4 0.00 635.00 0 10.6 192.20 -12.5 7.8 -8.6 7.8 1.5 91.40 0.01 0.0 OFF 0.590 -0.8 0.770 99.2 0.680 -1.6 0.765 99.2 CL CL
5 6.21 2045.00 0 13.3 194.00 -1.6 7.8 0.8 7.8 13.5 93.20 0.11 56.1 OFF 0.695 6.3 0.920 99.2 0.875 5.5 0.985 99.2 CL CL
6 23.61 1003.00 0 18.0 194.00 -7.0 7.8 -8.6 7.8 1.0 91.40 0.01 0.0 OFF 0.765 -28.1 0.925 99.2 0.790 -28.1 0.915 99.2 CL CL
7 31.69 1234.00 0 9.8 197.60 -28.1 7.8 -28.1 7.8 1.5 93.20 0.01 0.0 OFF 0.170 3.1 0.045 99.2 0.210 6.3 0.230 99.2 CL CL
8 35.42 1035.00 0 12.2 194.00 -15.6 7.8 -19.5 7.8 1.0 91.40 0.01 0.0 OFF 0.750 -28.1 0.915 99.2 0.775 -28.1 0.915 99.2 CL CL
9 33.55 2131.00 0 13.7 194.00 -28.1 7.8 -25.0 7.8 20.5 91.40 0.04 0.0 OFF 0.810 -6.3 0.975 99.2 0.840 -9.4 0.980 99.2 CL CL
10 36.66 1085.00 0 11.4 194.00 -28.9 7.8 -29.7 7.8 1.0 93.20 0.01 0.0 OFF 0.775 -28.1 0.945 99.2 0.795 -28.1 0.935 99.2 CL CL
11 21.13 2022.00 0 12.5 194.00 -25.8 7.8 -25.0 7.8 13.0 91.40 0.09 17.3 OFF 0.785 -1.6 0.925 99.2 0.810 -5.5 0.915 99.2 CL CL
12 34.18 1364.00 0 11.0 194.00 -11.7 7.8 -14.8 7.8 18.5 91.40 0.01 0.0 OFF 0.790 -10.2 0.830 99.2 0.800 -11.7 0.920 99.2 CL CL
13 30.45 1401.00 0 12.2 194.00 1.6 7.8 0.0 7.8 2.0 91.40 0.07 8.2 OFF 0.225 2.3 0.155 99.2 0.855 -0.8 0.965 99.2 CL CL
14 31.07 995.00 0 12.2 194.00 -23.4 7.8 -10.9 7.8 1.0 91.40 0.01 0.0 OFF 0.720 -28.1 0.880 99.2 0.425 -26.6 0.865 99.2 CL CL
15 12.43 1036.00 0 7.1 195.80 -14.1 7.8 -5.5 7.8 0.5 93.20 0.01 0.0 OFF 0.220 -1.6 0.265 99.2 0.705 5.5 0.205 99.2 CL CL
16 13.05 2219.00 0 14.9 197.60 6.3 7.8 5.5 7.8 14.0 91.40 0.13 65.9 OFF 0.265 5.5 0.755 99.2 0.835 -5.5 0.940 99.2 CL CL
17 16.78 2053.00 0 12.9 194.00 -23.4 7.8 -24.2 7.8 14.5 84.20 0.15 85.1 OFF 0.835 -9.4 0.945 99.2 0.890 -14.1 0.930 99.2 CL CL
18 29.83 1584.00 0 46.3 194.00 0.0 7.8 -3.1 7.8 2.0 82.40 0.13 60.8 OFF 0.310 5.5 0.860 99.2 0.815 -10.2 0.810 99.2 CL CL
19 36.66 2610.00 0 49.0 195.80 3.1 7.8 -3.1 7.8 20.0 82.40 0.07 3.9 OFF 0.335 0.0 0.600 99.2 0.435 -2.3 0.610 99.2 CL CL
20 25.48 1255.00 0 21.2 197.60 -10.2 7.8 0.0 7.8 0.0 86.00 0.01 0.0 OFF 0.150 -0.8 0.130 99.2 0.330 2.3 0.365 99.2 CL CL
21 26.72 1117.00 0 21.2 197.60 -7.8 7.8 -7.0 7.8 1.0 89.60 0.01 0.0 OFF 0.160 -26.6 0.845 99.2 0.095 -18.0 0.805 99.2 CL CL



I'm suspicious of the S-FT12 (SHRTFT12: O2 Bank 1 Sensor 2 Short term fuel trim) and S-FT22 (SHRTFT22) which both show constant 99.2%, the max value, but I don't know what this could be pointing to.

If anyone can take a look at the data and let me know your thoughts, it would be much appreciated!