How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask BMWDoc Your Own Question

BMWDoc
BMWDoc, Independent BMW shop owner
Category: BMW
Satisfied Customers: 6426
Experience:  20 years of experience working with BMW's. Independent European shop owner and technician.
14582033
Type Your BMW Question Here...
BMWDoc is online now
A new question is answered every 9 seconds

2000 bmw 740i: running lean..cause and repair procedure, thank you

Customer Question

2000 bmw 740i, has a 1634 code, running lean, bank 1 and 2. would like to find out cause and repair procedure, thank you
Submitted: 3 years ago.
Category: BMW
Expert:  BMWDoc replied 3 years ago.

BMWDoc :

Hello, I'm Jason. I will do my best to answer your question quickly and accurately using the information you have provided.

BMWDoc :

hello there. How many miles are on the car?

Customer :

hello, 135000

BMWDoc :

while I'm waiting, you're going to need to check for vacuum leaks using an inert smoke generator. Also, if you're starting to see any oil smoke on cold starts, it's very likely that you will need to start by replacing the air/oil separator on the rear of the intake manifold

BMWDoc :

this is the typical cause of lean running codes....

BMWDoc :

and if, while the car is idling, and you try to remove the oil cap, and you experience a lot of vacuum, this is another sign of a failed separator valve

BMWDoc :

if you do need to replace the valve, it's best to remove the whole intake, as the torx bolts holding the separator on will typically strip if you attempt to remove them with the intake in place

Customer :

and that is located on the rear of the intake/

Customer :

?

BMWDoc :

correct. This picture is from a '98, but very similar

Full Size Image

BMWDoc :

Another view:

Full Size Image

BMWDoc :

And finally, what it looks like off the intake

Full Size Image

BMWDoc :

If this is the problem, I also recommend a few set of intake gaskets, the front intake cover gasket, the tube that goes through the center of the intake, and the vent tube that runs just to the inside of the left cylinder bank, in the valley

Customer :

will this also cause no thottle response with accerator pedal?

Customer :

will this also cause no throttle response with accerator pedal?

BMWDoc :

that would have been helpful information in your initial question. Possible, but not likely

BMWDoc :

you could also have a failing air mass meter

Customer :

well i do have vacum when oil cap is removed, step on gas pedal while running, will not revive up, backfires at idle, will not accelerate

BMWDoc :

could be multiple problems, but the two I've indicated are the most common. Any diagnosis beyond that is somewhat beyond the scope of this format

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
 
 
 

Meet The Experts:

 
 
 
  • Roger

    BMW Master Tech

    Satisfied Customers:

    2906
    10 yrs. experience as BMW Master Technician, shop foreman and dealer.
< Last | Next >
  • http://ww2.justanswer.com/uploads/Guest/2008-02-15_191551_avatar.jpg Roger's Avatar

    Roger

    BMW Master Tech

    Satisfied Customers:

    2906
    10 yrs. experience as BMW Master Technician, shop foreman and dealer.
  • http://ww2.justanswer.com/uploads/EU/eurotec/2012-6-11_13153_mpjaphoto.64x64.JPG Marty's Avatar

    Marty

    ASE Certified Technician

    Satisfied Customers:

    406
    ASE & Bosch Certified Master Tech. Over 30 years experience.
  • http://ww2.justanswer.com/uploads/DA/dansciol/2012-7-7_16177_danpic.64x64.jpeg bimmaster's Avatar

    bimmaster

    BMW Technician

    Satisfied Customers:

    1817
    3 years dealer experience, master bmw tech
  • http://ww2.justanswer.com/uploads/bmwmaster/2009-05-09_062111_avitar.jpg Sam's Avatar

    Sam

    BMW Master technician

    Satisfied Customers:

    1043
    BMW S.T.E.P. graduate, 10 years BMW dealership experience
  • http://ww2.justanswer.com/uploads/hondatrx450/2010-01-18_231606_stuff_092.JPG mike's Avatar

    mike

    BMW Technician

    Satisfied Customers:

    694
    bmw master tech ase certified
  • http://ww2.justanswer.com/uploads/CA/caprio23/2011-12-13_155550_20111213105344.64x64.jpg Anthony's Avatar

    Anthony

    BMW Technician

    Satisfied Customers:

    628
    ASE Master Automobile Technician with over 20 years exp. in this field.
  • http://ww2.justanswer.com/uploads/bmwbum01/2009-12-28_205712_germany2000.jpg Thebmwbum's Avatar

    Thebmwbum

    BMW Foreman

    Satisfied Customers:

    533
    31 years BMW Experience
 
 
 
Chat Now With A BMW Mechanic
BMWDoc
BMWDoc
Owner
241 Satisfied Customers
20 years of experience working with BMW's. Independent European shop owner and technician.