rough idle

The 98.5 A4Q 2.8 with 111k miles idles kind of rough even after throttle body service from an independent I no longer patronize and after several bottles of fuel injector cleaner (applied at various
times over the past 2 years). Aside from replacing the fuel injector(s) at considerable expense, what else can I try to smooth out the idle? The car runs great.
One Subaru person suggested CRC Mass Airfow Sensor cleaner; is this something I should try on the Audi?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
KLS wrote:

Vacuum leaks?
CEL showing errors?
If you don't know that the MAF is causing codes it is better to not mess with it.
Pull engine error codes and start from there.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There are no error codes. The car had a complete tuneup at 90k miles by the dealer. This situation has developed slowly over time; the car was checked for the vacuum recall back in January 2005, no problems then. It was just in to the independent who did a 4-wheel alignment and replaced a tie rod end, and they found nothing.
Speaking of tie rod ends, shouldn't those last more than 2 years?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
This is a multi-part message in MIME format. --------------070708010201030903010308 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit
KLS wrote:

the problem developed over a period of time I would suggest that you have the system checked out by more than a visual exam. Pressure test the system. Also some shops have a system that tests for leaks with smoke.
Still plugs, wires, fuel and air filters should be changed as well.
--------------070708010201030903010308 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#000000"> <br> <br> KLS wrote: <blockquote cite="mid: snipped-for-privacy@4ax.com" type="cite"> <pre wrap="">On Wed, 10 Oct 2007 20:44:39 -0600, TonyJ <a class="moz-txt-link-rfc2396E" href="mailto: snipped-for-privacy@visi.com">&lt; snipped-for-privacy@visi.com&gt;</a> wrote: </pre> <blockquote type="cite"> <pre wrap="">KLS wrote: </pre> <blockquote type="cite"> <pre wrap="">The 98.5 A4Q 2.8 with 111k miles idles kind of rough even after throttle body service from an independent I no longer patronize and after several bottles of fuel injector cleaner (applied at various times over the past 2 years). Aside from replacing the fuel injector(s) at considerable expense, what else can I try to smooth out the idle? The car runs great.
One Subaru person suggested CRC Mass Airfow Sensor cleaner; is this something I should try on the Audi? </pre> </blockquote> <pre wrap="">Have you changed plugs, wires, fuel filter?
Vacuum leaks?
CEL showing errors?
If you don't know that the MAF is causing codes it is better to not mess with it.
Pull engine error codes and start from there. </pre> </blockquote> <pre wrap=""><!----> There are no error codes. The car had a complete tuneup at 90k miles by the dealer. This situation has developed slowly over time; the car was checked for the vacuum recall back in January 2005, no problems then. It was just in to the independent who did a 4-wheel alignment and replaced a tie rod end, and they found nothing.
Speaking of tie rod ends, shouldn't those last more than 2 years? </pre> </blockquote> A lot can happen to the vacuum system since January 2005 and given that the problem developed over a period of time I would suggest that you have the system checked out by more than a visual exam. Pressure test the system. Also some shops have a system that tests for leaks with smoke.<br> <br> Still plugs, wires, fuel and air filters should be changed as well.<br> </body> </html>
--------------070708010201030903010308--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

On older cars around the mid 1900s the following could be done without having to use diagnostics. Be careful not to damage things during the process. The Idle control valve may need a clean. Look at all of the electrical wiring for loose or broken wires and connections. Disconnect and reconnect electrical connections. Clean all the earth connections. Disconnect the relays and reconnect them. Look at the rubber hoses to the inlet manifold and the fuel pipes. It can be one or more of the many sensors that is not functioning properly, a connection, wire or the ECU etc. Most of the sensors can be checked with a multimeter.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.