QuestionQUESTION: hi there, have bought an a3 which normally sits really quiet ( you would not know the engine is on). Pushed it fairly hard yesterday to see how it performed e.g revd high before changing up, pulling away 0-40 speeds, etc. nothing to bad and did not red line it. now the engine sounds awful. idles just below 1000, engine vibrates and generally sounds like a tank. Any help would be appreciated. what have I done to my lovely car. ? By the way its a 2004 with 45000 miles, just gone through mot no problems, Thanks
ANSWER: Hi phill.
this is a tricky one, what exactly do you mean by vibrate?? look at the rev counter when it is idling, does it flactuate with up an down?? if so then it could indicate an ignition or fuel fault, if it doesnt then it indicates a faulty engine mounting.
start with a visual check of the engine, make sure all pipes, hoses and sockets are connected properly, maybe some thing let go, then check that the mountings and all the fixtures are sitting properly and tight.
if no obvious faults are found it could be a misfire either caused by the ignition system or fuel system, in which case the easiest way would be to have a diagnostic done,
if possible have the diagnostic done and forward it to me so i can advise you further.
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QUESTION: thanks for your help so far, when I say vibrate its like the diesel engine from my old BMW. not a lot but highly noticeable if that makes sense. then every 2 or 3 min it rocks back and forward to a greater extreme for about 5 seconds. the rev counter does fluctuate only a small amount around 800 to 1000, if left running the revs drop for 10 secs and engine sounds like it might cut out and then kicks back in again. have checked all the mountings and hoses which seem ok so I guess the next step is the diagnostics. Are audi diagnostics usually reliable. (any idea of cost?) previously I had a fiat and 3 diagnostic checks and 3 different remedies left me no further forward. Lastly would any of the possible causes occur from one hard drive (which is what happened) rather then continuous wear and tear. cheers
AnswerSounds like a misfire, maybe one cylinder is 'dead' i.e not firing. you say the milage covered is 45000mls, have the spark plugs been replaced yet??? Audi service interval is 60000 Kms ( 37500mls) for platinum tip plugs and 40000kms(25000kms) for the normal carbon tip plugs. your vehicle should have the platinum tip ones which are identifiable by the fine needle like tip while the carbon tip ones have a thick black tip.
one problem I know of on the FSI engines on the fuel pressure pump that is located on the cylinder head, there is a one way valve that usually gives up and can cause the problem you describe, but id still advise you to have a diagnostic carried out. to avoid buying unnecessary and expensive parts.
Also I doubt the extreme driving caused the problem, rather I think the fault was hiding under the surface and the driving just brought it to the surface, ( I usually put a car through its paces before handing it back to the owner to make sure it is in proper condition)
As for your other question yes Audi diagnostics are very reliable provided you use the correct type of diagnostic tool, and the person understand the information that the diagnostics produces.
what I mean by the correct tool is that there are 2 types of diagnostics available, one is the universal OBD2 code reader that produces generic codes that are standard on all OBD2 compliant cars, basically the law states that manufacturers have to standardize their emission control systems and make them available to the public, this is where generic code readers come in, they are capable of picking up faults on the vehicle that directely influence the emission system, like fuelling.these codes are identical in every make of vehicle and can be identified by a 'P' followed by numbers eg P0xxxx
On the other hand you also have the option of using a dedicated diagnostic tool, which picks up factory fault codes that are specific to that particular make and also the standardized OBD2 codes, apart from this the dedicated soft ware can also read the information from the different sensors in real time, there fore making a diagnosis easier, and eliminating the need for guess work,( as long as the person understands the information before him that is)
As far as the cost goes it varies from location to location, but there are a alot of people who have invested in independent diagnostic software called VAGCOM who usually offer the service for a small fee and even free at times, try a site called Audi-Sport.net and find some one close to your location that can help you out.
Also please note that diagnosis is only capable of picking up faults on the electrical sensors and actuators so if you have a mechanical fault then it may not be picked up, though the good news is that most mechanical faults do cause faults on the electrical system, and vice versa, and yours being a newer car with more sensors compared to older vehicles the chances of picking some thing up are higher,
Hope this helps, Good luck
