4kq acceleration issue

[Ed Kellock]

My first reaction, from a systemic point of view, is that it sounds like
your car has been running poorly for some time, suffering from vacuum leaks,
a fairly common problem considering the age and design/assembly of the
engine.  Vacuum leaks cause the mixture to be too lean.  This causes hard
starting, especially in the cold.  If simple adjustments have been made
along the way to get it to start and idle, then that will cause the idle
speed to be too high.  Off idle, the car will still be too lean and that can
cause the spark plugs to load up with deposits and cause the dieselling when
the engine is shutdown.  Ultimately, the high heat can cause the catalytic
converter to fail.  Your acceleration problem sounds a lot like a plugged
cat which will get very, very hot which could be melting/burning things
around it, hence your burning smell.

A muffler shop could do a backpressure test to test the cat.  Or you could
just remove it, even temporarily, to see if you can get some performance
back.  This would be strictly for test purposes only.  ;-)  

There are lots of places for vacuum leaks.  There is quite a bit of standard
vacuum line running around in there, along with some larger rather
specialized breather hoses, etc.  Also, each fuel injector has a plastic
seat that screws into the head.  The injector pops into this seat.  These
can come loose and leak air too.  The large intake boot should be checked
thorougly too.

It'll be a bit of a project, but it sure sounds like there are some real
gains that can be realized with just some time under the hood.

The clacking lifters is pretty much a whole different situation and
unrelated.  It is usually possible to elminate or greatly reduce the noise
with a different grade/quality of oil, even a simple oil change or topoff.
If they quiet down as the engine warms, then it's not overly critical.  Make
sure the oil level is right.  If it's dirty, change it.  If you don't notice
any appreciable improvement, wait until you get the engine running reliably
and post again about the lifters.

Ed





> -----Original Message-----
> From: quattro-bounces at audifans.com 
> [mailto:quattro-bounces at audifans.com] On Behalf Of Rory [Armodis.List]
> Sent: Tuesday, February 13, 2007 12:57 AM
> To: quattro at audifans.com
> Subject: 4kq acceleration issue
> 
> 
> Hey audifans
> 
> I have a stock 85 4000 quattro that needs a lot of love =)  
> Based on a couple references from audifans, I believe the car 
> has an Inline 5 2.2L 10V CIS-E.
> 
> - The valve cover leaks and the lifters clack pretty bad.
> - It idles high, usually a little above 1000.
> - It has some trouble starting in the cold.  The colder it 
> is, the harder it is to start.
> - I have to give it some gas to get it to idle steady but 
> then its good to go.
> - Sometimes it will almost stall until I get the car moving 
> and then it's ok.
> - The temperature gauge usually sits between the 1/2 to 3/4 
> mark unless I have the heater on and then it drops down to 
> between 1/4 and 1/2.
> - The motor diesels.
> 
> The fuel pump, fuel pre-filter, and fuel filter have all been 
> replaced. I do not know when the plugs, wires, cap and rotor 
> were last replaced.
> 
> Last night the car suddenly started having acceleration 
> problems in any gear.  I kept the RPMs above 4000 and the 
> acceleration problem seemed to go away long enough for me to 
> get on the highway and get home.  This morning and through 
> the day the car seemed to function as it usually does.  
> Tonight the acceleration problem came back and didn't go 
> away.  I limped it home and could smell something burning, 
> but didn't get a good whiff.  I think it was plastic like.
> 
> In looking at the Bently it seems this could be caused by a 
> leak in the air intake system, differential pressure outside 
> of tolerance, or several other things.  In searching through 
> the archives I found several references to the air intake 
> leak and one about the oxygen sensor.  I tried removing the 
> oil dip stick as recommended in a post from the archives to 
> test the air intake issue, but that didn't change anything.  
> Several posts are in reference to turbo motors, so I'm not 
> sure how that plays into things.
> 
> I know the car has quite a few issues that could cloud what 
> is causing the acceleration problem, but any ideas on where 
> to start or what is most likely to be the problem would be 
> deeply appreciated.  If there is anything I *must* do to 
> narrow the problem down please let me know (ensuring the idle 
> screw is tightened down?).  I'm saving my pennies for a motor 
> swap, so I'd be happy if I could just get it running fairly 
> normal again.  Hopefully long enough to make it through 
> snowboarding season =)
> 
> Thanks in advance!
> Rory
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