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 Jerry Your Own Question

Jerry
Jerry, Master Mechanic
Category: Audi
Satisfied Customers: 13227
Experience:  ASE Master, 30+ years exp. imports and domestic, former shop owner
2947720
Type Your Audi Question Here...
Jerry is online now
A new question is answered every 9 seconds

Audi A4 has severe vibration and shaking under acceleration,

Resolved Question:

Audi A4 has severe vibration and shaking under acceleration, off power car is smooth, what could be the problem?
Submitted: 5 years ago.
Category: Audi
Expert:  Jerry replied 5 years ago.
Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.

What year is it?
Does it feel like the engine has a miss in it?
Customer: replied 5 years ago.
no miss at all, engine runs smoothly at idle, and revs smoothly...
Customer: replied 5 years ago.
and its a 2004
Expert:  Jerry replied 5 years ago.
There could be a problem with one of the inner CV joints. That will give a vibration when under an acceleration. Normally will feel like a second order type vibration. That is that the axle wobbles 2 times for each one revolution.

You would want to raise the vehicle up, (preferably on a lift) and spin the wheel(s) by hand and see if the axle moves up and down when you reverse the rotation of the wheel. As the inner part starts to turn, you may notice that the axle takes some time to start turning, (play in the CV joint)

More than likely there is only one that is bad, so you can compare each side to the other.

Unless, it is in the driveshaft itself, which would be more of a violent rumble that seems to become more less when you get up to a higher speed.
Customer: replied 5 years ago.
yea it's actually more like a violent rumble, so you do not thing it has anything to do with the catalytic converter? in the even that it is the drive shaft...would the entire shaft have to be replaced?
Expert:  Jerry replied 5 years ago.
There are normally shops that specialize in driveshaft work. They could possibly rebuild it if it is not bent. However, it is most times more cost effective to replace it with a good used one if there is one available.

The P0420 code is just that the catalytic converter is not cleaning up the exhaust gases as efficiently as it should, that wouldn't give any running problems, (or vibration) only a lack of power if it were to become clogged up.

Of course, you will want to be sure that the transmission mount is good and not allowing the driveshaft to sort of bounce wheile your driving.
Customer: replied 5 years ago.
one more question, so is it a possibility that it could also be the tranmission mounts that are bad? would that cause the rumble, and if it is the transmission mount would i still have to replace the driveshaft or do you think just changing the mounts could eliminate the problem?
Expert:  Jerry replied 5 years ago.
I fthe mount is allowing the trans to bounce up and down when under a load, that could be the whole problem. Normally you can spin the drivetrain while on the lift and see if the driveshaft is true. The trans mount could be checked by pushing up on the rear of the trans and see if it moves.
Jerry, Master Mechanic
Category: Audi
Satisfied Customers: 13227
Experience: ASE Master, 30+ years exp. imports and domestic, former shop owner
Jerry and 6 other Audi Specialists are ready to help you
Customer: replied 5 years ago.
okay....sounds like that definetely could be the problem, one more thing, is it normal to see a little oil inside the hole that the ignition coil and spark plugs go into? if not what could be causing that?
Expert:  Jerry replied 5 years ago.
The valve cover gasket has a part in the middle that should seal up the spark plug holes. That is where the oil gets into the holes. It shoudl really be rather dry in there. the oil settles around the plugs and can eventually seep into the combustion chambers.

You may want to replace the valve cover gasket to avoid any problems in the future with that.
Customer: replied 5 years ago.
would replacing the valve cover gasket solve that problem?
Expert:  Jerry replied 5 years ago.
Yes it would. (sorry, my pc was acting slow..I had to edit the post about that)

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:

 
 
 
  • AudiDoc

    Independent Audi Shop Owner

    Satisfied Customers:

    1681
    I've been working on Audis since I was 18 and own an independent Audi repair and performance shop
< Last | Next >
  • http://ww2.justanswer.com/uploads/audidoc/2008-12-23_175252_headshot.jpg AudiDoc's Avatar

    AudiDoc

    Independent Audi Shop Owner

    Satisfied Customers:

    1681
    I've been working on Audis since I was 18 and own an independent Audi repair and performance shop
  • http://ww2.justanswer.com/uploads/35/350matt/2012-6-7_182356_matsavatr.64x64.jpg Matt's Avatar

    Matt

    Engineer

    Satisfied Customers:

    461
    Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
  • http://ww2.justanswer.com/uploads/MI/mikeamechanic/2013-4-2_175558_photo.64x64.JPG Mike Kelly's Avatar

    Mike Kelly

    Audi Mechanic

    Satisfied Customers:

    259
    17 years experience as a auto mechanic, foreign and domestic.5 years running my own repair business.
  • http://ww2.justanswer.com/uploads/FourRingsTech/2010-01-26_135603_GetAttachment.jpg Michael Miller's Avatar

    Michael Miller

    ASE Certified Technician

    Satisfied Customers:

    241
    ASE Master Technician. Audi certified, including R8 and TDI (clean diesel).
  • http://ww2.justanswer.com/uploads/NA/nabilc/2011-1-24_205715_jap500.64x64.jpg Billy's Avatar

    Billy

    Trainer/Master tech.

    Satisfied Customers:

    229
    Trainer 8+ years, Master tech. 10+ years, SAE member
  • http://ww2.justanswer.com/uploads/tsmodie/2009-6-10_144056_tim.jpg Tim Mohr's Avatar

    Tim Mohr

    ASE MASTER TECH

    Satisfied Customers:

    204
    30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
  • http://ww2.justanswer.com/uploads/CA/caprio23/2011-12-13_155550_20111213105344.64x64.jpg Anthony's Avatar

    Anthony

    ASE Certified Technician

    Satisfied Customers:

    174
    ASE Master Automobile Technician with over 20 years exp. in this field.