1985 Audi 4000s idling rich

My Audi 1985 Audi 4000 is running perfectly well when warmed up after about one minute.
The problem is rough idle and running rich when starting the cold
engine.
I replaced a leaking valve cover gasket, airfilter and sparkplugs, checked the idle valve, but have not been able to pinpoint the cause.
Any hints would be appreciated
marti-
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
How do you know it is running rich? Is it also idling either too low or too high?
Check your coolant temperature sensor for the fuel injection. Check for a weak ign coil. Check the fuel pressure and the current to the fuel pressure regulator. Check the fuel distributor flap level according to the Bentley. Oh and clean that area too! ;-) I have seen bad/leaking fuel injector seals cause some idling problems too! You can spray some carb cleaner at them to see if the idle changes any.
--
later,
dave
(One out of many daves)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 8 Jun 2008 13:41:15 -0500, "dave AKA vwdoc1"

Dave,
Yes, it is running rich because you can smell the excess gas and the engine stutters, most likelybecause the combustion chamber is temporarily flooded with gasoline.
Thanks for the tips, they make good sense!
marti
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
hmmm I have not seen an '85-87 Audi 4000 in awhile. The system is a little different than my '83 Audi 4000S. Is there a Cold Start Valve that might be staying on a little too long? Maybe you could try unplugging it electrically and starting the engine cold to see what it does.
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 9 Jun 2008 19:28:27 -0500, "dave AKA vwdoc1"

Yes, it has a cold start valve, unplugging the wire does not cause any change, which does not seem right either. Will keep exploring.....

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Is the cold start valve leaking?
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 10 Jun 2008 17:20:28 -0500, "dave AKA vwdoc1"
I don't see any outside leaks. Now, I just looked at my 5000s Bentley Book and it talks about the throttle switch. There is a throttle switch on this 85 4000s also, when I disconnect the connector the idle speed zooms up.
The adjustments seem pretty convulated. I think I'll just put up with this, since the car runs perfect once it warms up in about less than a minute.
I'll have most manuals, but I think I'll get the Bentley manual for this 1985 4000s.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sometimes the cold start valve leaks fuel on the inside creating a richer mixture. ;-) I think the Bentley manual instructs you on how to check them.
Yes it could be a problem with the throttle switches, one for idle and one for wide open throttle....if so equipped.
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 11 Jun 2008 21:46:15 -0500, "dave AKA vwdoc1"

Dave, Thanks for all the input.
These old cars can be a challenge. But than again, everything gets older from day one....

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
dave AKA vwdoc1 wrote:

It might also be an idea to run a bottle of Techron injector cleaner in a few tanks.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    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.