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7 Series - E38 (1995 - 2001)

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  #1  
Old 06-28-2013, 08:26 AM
NoCornersCut NoCornersCut is offline
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Location: Virginia
 
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Mein Auto: 2000 740iL
E38 M62 Elusive Code + Electrical Issue

Hey everybody,

I just joined but have been combing these forums for weeks now searching for solutions. I recently got a 2000 BMW 740iL, I am a mechanic, saw the check engine light was on, heard lifter ticking...no biggie for me. Until I scanned it, P0102. MAF or VAF Low cir blah blah blah. Cleaned the MAF, took apart the entire intake system, inspected it for vac leaks, cracking elbows/tubing. I then notice the secondary air valve is missing a hose.(The hose with fast connect plastic end pieces on it) I remove the front bumper to access the secondary air pump. It's not plugged in. So, I plug it in. I then fashion a vacuum hose that fits onto the pump and valve perfectly...lol . I refuse to dish out 40 bucks for a hose. I snug everything up and run a quick start up to make sure the air pump is operating correctly, I start the vehicle, to my surprise everything seems to be working (minus the same elusive p0102). I then find the blue and black vac hose coming from the Air Switch I cant recall if thats the correct name for that device due to the amount of reading I've been doing. It's plugged with a bolt. I hook it to the air valve along side my new hose. Same code, rough idle(almost feels like a bad motor mount only once shes warm the vibration goes away) .

I think I have checked every other possible source other than swapping the MAF, however from what iv'e read if you disconnect the MAF and see engine idle improve then it doesnt really point at the MAF anymore. On top of that I found paper work in the car saying the MAF was replaced roughly two years ago... with a Bosch. Also, when I purchased the vehicle the previous owner stated that the car will stall at low rpm such as approaching a red light and things like that. I thought instantly CPS sensor (mine has two). After reading more with this P0102, a bad MAF can cause stalling at low speeds, just like a CPS will. So I am truely at a loss here, I don't have the funds to start throwing sensors at it. I want to be making a very accurate decision to solve this issue the first time I try. Any advice would be appreciated.

Oh one more thing.. I check the fuse panel today, (under hood) found a couple missing fuses... my air conditioning buttons LEDS work for a few seconds after I start the car then they flicker and die, however the function of the actual button still works. If anyone knows where there are more fuses and or relays to examine and check I would be all ears.


Thank you for reading this and I am proud to be a new member of this community


-Matt
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  #2  
Old 06-28-2013, 12:20 PM
umewes umewes is offline
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Location: NJ
 
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Mein Auto: 2001 740i
Had very similar situation about 10 month ago. Codes - rough idle - engine would quit running and more. Turned out to be the electrical connector for MAF. I cleaned the pins and applied a tie wrap to hold the cable in place. Never had the code nor the engine quitting again.
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  #3  
Old 06-28-2013, 12:27 PM
NoCornersCut NoCornersCut is offline
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cool one more question though.

How did you clean the pins? Spray em down with CRC? and where to you apply the cable tie, I mean in what spot. Thank you
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  #4  
Old 06-28-2013, 02:27 PM
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ebida3 ebida3 is offline
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Location: High Point, NC
 
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Mein Auto: 2001 740iL
Behind the battery is a whole bank and relays and fuses. Sure sounds like a bad MAF.
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  #5  
Old 06-28-2013, 04:24 PM
NoCornersCut NoCornersCut is offline
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Roger that, and thank you for the fuse/relay info...new to bmw, lol. I guess ill take the leap and swap the maf. I will update and let you guys know what happens.


Thank you for the help. And trust me I don't normally ask for help.... then I bought a bmw.
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  #6  
Old 06-28-2013, 05:13 PM
Mayorchuck Mayorchuck is offline
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Mein Auto: '96 740iL
Only other thing I would suggest with the P0102 is to check the battery voltage. It's probably the MAF itself but these cars are very picky and low voltage can have you chasing your tail with an E38. On your car, the VW version MAF, which is identical to the BMW, is much cheaper.

http://www.amazon.com/Bosch-02802180.../dp/B000CF5VRA

You can unlock the cluster to check the voltage and do other tests. As far as your IHKA LED's, mine have done that for 3 years. Seems to be worse in the heat. I just purchased a used on from a member in another forum.

I know you are a mechanic but the electrical gremlins of the E38 will challenge you. A few links to bookmark:

e38.org
http://www.meeknet.co.uk/e38/
http://www.bmw-planet.com/diagrams/release/us/
http://bmw.workshop-manuals.com/7_Se...index.php?id=1
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  #7  
Old 06-28-2013, 05:20 PM
NoCornersCut NoCornersCut is offline
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Thank you Mayor,


Very nice info. Also, I did replace the battery early on. (dead cell).Possibly caused by the previous owner not hooking up the vent. It's looking like the MAF is the culprit, will do the VW swap and save some cash.


-Matt
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  #8  
Old 06-28-2013, 06:36 PM
umewes umewes is offline
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I used CRC contact cleaner. Spray both sides. The pins inside the plug appeared somewhat loose. I used a tie wrap to provide strain relief - basically attaching the cable to the plug. That way nothing pulls on the individual wires.
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  #9  
Old 06-28-2013, 09:55 PM
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ebida3 ebida3 is offline
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Location: High Point, NC
 
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Don't be weirded out to ask. That's why we are here. I may have had experience with something that else may not have. we are all here to help each other.

With that said mail my diagnosis check to:


Friggin BMW
Please start St.
Gonna get stuck, USA


Last edited by ebida3; 06-28-2013 at 09:56 PM.
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  #10  
Old 06-29-2013, 05:04 AM
NoCornersCut NoCornersCut is offline
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lmao, well today is the day! 8am now, by 3 or 4 the problem will be solved...I hope. Thank you guys for everything, very cool people on these forums. Oh yeah, ill make sure and get the check sent out asap.
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  #11  
Old 06-29-2013, 05:49 AM
NoCornersCut NoCornersCut is offline
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Update important

Ok,


I was re-checking all vac lines/hoses triple checking anything easy to overlook. I unplug MAF, engine moved into new program. No difference in idle... plugged MAF back in, engine shut off. Keep in mind have done this exact same procedure and once plugged in engine would NOT cut off, now it does cut off when I plug MAF back in. Also, noticed smoking (smells like burning rubber) coming from passenger side under engine. Not tons of smoke but I do notice it and smell it. Any advice?
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  #12  
Old 06-29-2013, 05:59 AM
NoCornersCut NoCornersCut is offline
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Update cont'd

Ok,


Just ran the same procedure as above and the engine didnt die. Isolated incident? Also, when I purchased the car I found that there wasn't an air filter in the air box. I put a new one in, however it was like a standard PRO-TEC filter. When I put in the new filter the check engine light went away... then came back a day later. One theory I am having is maybe the filter is too thick? Can't suck enough air through it to give MAF proper level of flow there for PCM is throwing a code? Is this a possibility?


-Matt
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  #13  
Old 06-29-2013, 02:28 PM
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ebida3 ebida3 is offline
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Location: High Point, NC
 
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Same code same problem

You have to start somewhere and this is the most logical.

replace MAF

Last edited by ebida3; 06-29-2013 at 02:29 PM.
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  #14  
Old 07-02-2013, 10:33 AM
jitsjaf2009 jitsjaf2009 is offline
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Mein Auto: 1995 325i Convertible
Are you also aware of the fuses under the passenger seat? Often get corrosion in there...!
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  #15  
Old 07-02-2013, 11:25 AM
NoCornersCut NoCornersCut is offline
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I wasn't aware of those...and funny you should mention them because I did notice the previous owner had spilled A LOT of coffee in that general area. checking now, also got the VW MAF and same old code, cleared it, start once shut off, turn on code comes right back...
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  #16  
Old 07-02-2013, 11:33 AM
NoCornersCut NoCornersCut is offline
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and hey do i need to remove the seat to access those fuses?
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  #17  
Old 07-02-2013, 01:57 PM
jitsjaf2009 jitsjaf2009 is offline
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Yes, you would have to remove the seat (might be able to manipulate things enough to get "eyes on" without seat removal. Did you do the "brake Cleaner" search for vacuum leaks? It doesn't take a lot between the MAF and the intake manifold....
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  #18  
Old 07-02-2013, 02:45 PM
NoCornersCut NoCornersCut is offline
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Buyin brake clean in the morning to triple check it, and pulling the seat tomorrow as well. The rain in va beach has been insane lately... like living in the tropics.
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  #19  
Old 07-03-2013, 04:45 AM
NoCornersCut NoCornersCut is offline
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Used brakleen, no luck. Not even a faint change in idle. No leaks confirmed. Will the secondary air system throw a p0102 if the pump isnt functioning?
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  #20  
Old 07-03-2013, 05:39 AM
NoCornersCut NoCornersCut is offline
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Just ordered a brand new BOSCH MAF. Lets see if that works.. VW sensor was used, and the most delicate parts on the sensor were severely oxidized. So, I ordered a new one from BAPGEON, pretty cheap $218 brand new. Will update after install.
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  #21  
Old 07-03-2013, 08:28 AM
NoCornersCut NoCornersCut is offline
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Ok, just took my hose off my secondary air pump.. no air flow what so ever. My question is will a failed SA Pump cause a P0102 code. If so I think thats my problem. Checked all the vac lines for suction everything else seems to working and yes I know I have to replace the air valve when I replace the pump
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  #22  
Old 07-03-2013, 09:55 AM
NoCornersCut NoCornersCut is offline
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This is gettin crazy man.... removed passenger seat check fuse for pump, all good, I take apart the upper panel under the hood to access the lower relay/fuses... the SA Pump relay has been tampered with, highly corroded prongs.. it is also a possibility whoever removed it may have put it back in the incorrect way. so now I need a diagram to show the orientation of that specific relay.. this is a nightmare.. I love what I do but jeez. When will this end!!?
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  #23  
Old 07-03-2013, 03:31 PM
Mayorchuck Mayorchuck is offline
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Mein Auto: '96 740iL
Go here:

http://www.bmw-planet.com/diagrams/r...8new/index.htm

Select your model.
In the search box on lower left, type 6304 and hit Search. Click on each sub folder to see pic, pin puts and other into. Click on 'Next'. The last 6304 entry is the connector pin into.

To see the schematic, Type 'air pump' in the search box. You have the 7.2 DME I believe so click on the appropriate drop down link.
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  #24  
Old 07-09-2013, 07:01 AM
NoCornersCut NoCornersCut is offline
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UPDATE - SOLVED


Ok guys thanks to all of your info and a little elbow grease my BMW IS BACK ON THE ROAD!!! Here's why:

Ok, swapped the MAF with a new BOSH MAF. Code Gone...(P0102) Now here's the really interesting part. After removing the passenger seat and checking the SAS Fuse, removing the ECU to access the relay for the SAS Pump... I checked my relay, click click, good to go. However When I reinstalled the same relay and fired the car up the SAS system starts working!!! I think whoever messed with that relay before (broken connector to hold it in place, bull in china shop) may have reinstalled incorrectly...


So I would like to thank

Ebida3
Mayor Chuck
JitsJaf2009
UMEWes

Without you guys I'd still be hanging out to dry. I can't thank you enough for helping me out!

Until I have another nightmare....... farewell!


-Matt
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  #25  
Old 07-09-2013, 07:09 AM
jitsjaf2009 jitsjaf2009 is offline
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Mein Auto: 1995 325i Convertible
Thank you for getting back and letting us know the resolution. You taught, we learned...It works when we all 'play'. Glad your machine is back to 'healthy'.
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