bosk0691

my A4 has a loud noise on startup that last for several seconds and then stops. It almost sounds like a leaking exhaust but there is no leak (that I can see from the exhaust). It only happens when it's a cold start.

Any ideas??????

Thanks

Jazz

its called a choke.....to warm up the motor.

bosk0691

Thanks Jazz. That's good to know but I thought only cars with carburetors had chokes.
I should have included my car's profile. It's an '05 1.8 quattro.

So, that "one part rubber, three parts Krazy Glue." is the fix for a broken choke?

Jazz

ok, in F.I. cars its not called a choke, its called a fuel Enrichener (choke) is this your 1st F.I. car?? may i be the first to say welcome to the 21st century!!

Jazz

had to edit it as i was getting mad...lol

bosk0691

I've only ever had F.I. cars... But I remember my aunt had a 1980 something volvo that every time she started it cold she would have to pull out the choke.

The A4 runs fine but the overly loud sound that the fuel "Enrichener (choke)" causes is annoying. A change in the tone on start up is probably normal but the loudness of what I'm hearing makes me think that something is wrong or about to go wrong.

Jazz

the loudness is the more fuel less air...its fine, your RPM is about 1200 when cold and 800 when not...you might even hear the turbo spool down when the choke turns off.

whoace

"fuel enrichener"? turbo spool down? ok....Is this your first F.I. Car?

bosk, if you think you have an exhaust leak, plug it with some rags and it'll make the leak more noticeable. You can also try plugging it with your hand(s). If there's no leaks, it should build enough pressure to break the seal your hand(s) made.

VeiledLt

No he's right although its not a fuel enricher per sae it's just an increase in the throttle plate position (gas pedal) so the engine has a shorter warm up period, same thing you used to do in a carbed car although back then we just held the pedal down, lol now its automatic. As far as turbo spool up/down is concerned it depends on if the turbo is constantly run or if it kicks in at a set RPM. However if you do have an exhaust leak you'll always hear it regardless of hot or cold, if its on the manifold it can be a faint ticking sound, or if its on your pipe its kinda of hard to hear or if its on your cat or your muffler you'll hear it. Hope that helps.

-Lt-

whoace

Your car has a high idle, when you first start it, because it is running off a base map. (open loop)

As for the turbo spooling down, you can't spool down a turbo when there's negative pressure (vaccuum). How can you set your turbo to not "constantly run" or to "kick in" at a set rpm? Turbos work off manifold pressure. This is not V-TEC on a Honda.

If you have an exhaust leak that is at one of the flanges, you may not hear it when the system warms up. The gasket gets a little bigger and seals up the minor leak.