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 AudiDoc Your Own Question

AudiDoc
AudiDoc, ASE Certified Technician
Category: Audi
Satisfied Customers: 6456
Experience:  Independent European garage owner. Over 20 years experience
14582033
Type Your Audi Question Here...
AudiDoc is online now

RA-AMM

Customer Question

Hello my audi A4 Cabriolet 3.0 litre manual 2002, is shuddering, or vibrating very badly. i have changed my catalytic converter and it is still doing it. i Have had all my coils checked, they are fine, I have had the engine pressure checked its fine, could you please give me a possible answer to this fault as it seems to be confusing every one. My car has been on numerous computers and no fault is being indicated. My only other option would be to take it to an Audi dealers to see if they can diagnose the fault. I have been told that it could be a bent valve or a cylinder fault. I changed both CATS and all the sensors

Submitted: 3 years ago.
Category: Audi
Expert:  AudiDoc replied 3 years ago.
Can you please tell me if an engine scan was done, and what fault codes were stored? This will allow me to give you some specific steps to attempt to repair.

Thanks
Jason
Customer: replied 3 years ago.

Hi, no I haven't had an engine scan done, I have only had the checks I mentioned done. I don't know the fault codes stored, the car has been on various computers that give different readings but they all seem to be directed to the CAT hence why i changed it. A few years back Audi told me I needed a new CAT, I then took it to a specialist garage who advised me to try a Cleaner which is poured in the petrol tank, it worked for a couple of years. The car then started to vibrate and shudder after that from time to time so I continued to try using the cleaners, again it worked. Then it started to vibrate much harder, but it would start and stop when it wanted, it felt like a faulty sensor because of the pattern it took. Since November last year it has been constant, where as before the car seemed to cure itself. I hope this is some help. I went to one specialist whose computer was saying there are cylinder faults but that was only on there computer I got that information.

Expert:  AudiDoc replied 3 years ago.
If they're using an Audi specific scan tool, and are seeing cylinder misfires, I'd start to consider faulty ignition coil packs, especially if the engine light is flashing at times. The shuddering and vibration shouldn't be cat-related. I wish I could assist more, but without the faults codes, it's somewhat difficult.

What Customers are Saying:

 
 
 
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
< Previous | Next >
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
  • 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
  • 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
  • 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
  • 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
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex
 
 
 

Meet The Experts:

 
 
 
  • Matt

    Matt

    Mechanical Engineer

    Satisfied Customers:

    182
    BEng hons Mech engineering, in auto industry 22 years
< Last | Next >
  • http://ww2.justanswer.com/uploads/35/350matt/2012-6-7_182356_matsavatr.64x64.jpg Matt's Avatar

    Matt

    Mechanical Engineer

    Satisfied Customers:

    182
    BEng hons Mech engineering, in auto industry 22 years
  • http://ww2.justanswer.com/uploads/audidoc/2008-12-23_175252_headshot.jpg AudiDoc's Avatar

    AudiDoc

    ASE Certified Technician

    Satisfied Customers:

    1583
    Independent European garage owner. Over 20 years experience
  • http://ww2.justanswer.com/uploads/MI/mikeamechanic/2013-4-2_175558_photo.64x64.JPG mike_a_mechanic's Avatar

    mike_a_mechanic

    Mechanic

    Satisfied Customers:

    70
    17 years experience as a auto mechanic, foreign and domestic.5 years running my own repair business.
  • http://ww2.justanswer.com/uploads/FO/fordtwo/2014-12-19_163422_arrepair.64x64.jpg Robert's Avatar

    Robert

    UK Qualified Car Technician

    Satisfied Customers:

    37
    Fully qualified 19+yrs exp/self employed technician in the UK
  • http://ww2.justanswer.com/uploads/IN/indytech/2013-8-8_102717_SantoDomingo146598x6402.64x64.jpg Greg's Avatar

    Greg

    Technician

    Satisfied Customers:

    1080
    Automotive diagnostic tech
  • http://ww2.justanswer.com/uploads/TE/techmachine/0601821347169_717372168_8940977_39623330_o.64x64.jpg Ross's Avatar

    Ross

    Diagnostic and repair technician

    Satisfied Customers:

    453
    Licensed diagnostic and repair technician