4500rpm cutout and boost in neutral. Codes 2223 and 2342

PeterBergin at aol.com PeterBergin at aol.com
Wed Mar 28 21:24:05 PDT 2012


Looks like you covered all the bases.  I would unplug the MAF and see  if 
any thing changes.  And you have sparks around the  distributor.  I would 
check those two carefully.  When my MAF failed  it acted similar with no codes 
or check engine light (If you have one),
 
Pete
91 Avant sold last summer
02 S6
 
 
In a message dated 3/28/2012 8:02:00 P.M. Central Daylight Time,  
audisport44 at yahoo.com writes:

Hello everyone,

I haven't been part of the list for some time now but I'd like to revisit 
an  issue I've had with my 200. I didn't have time to mess with the car due 
to  other priorities but I'd like to see if I can figure out the problem this 
 time around.

The car is a sedan with almost 200k on  the odometer.

My main concern is that I cannot rev  the engine past about 4500 rpm. It 
gets stuck at that point and the tach  needle bounces as if it's hitting a rev 
limiter. While this happens you can  hear the car misfiring severely. The 
car acts this way wether it is in neutral  or under load. Also easing onto 
the gas is the only way you can even get it up  to 4500. If you try to give it 
too much it'll choke right away and start  misfiring. The weirdest part is 
that it actually builds boost in neutral. I  know I've said this before and 
nobody on here believed me so I'm including a  video of  the phenomenon. The 
digital gauge in the car says it's building  boost and so is the mechanical 
one I temporarily hooked up(this is a verified  good gauge that I used in 
my B5 S4). The video shows vacuum at idle and boost  when it hits that 
cutoff. Also you can see the tach and where it stops when  you rev the car. It 
will never go past that no matter what you do and what  the
condition is.

Here's a list of things I've  done to try and track this down:

-Pressure test (all good and  held at least 20psi from what I recall)
-Replaced ecu with  another good unit
-I did a fresh headgasket, valve job and timing belt  (timing is on 100%), 
I can attest there is nothing physically wrong with the  engine
-Cams were checked for alignment at tdc and the Os line up as they  should
-Replaced O2 sensor with original bosch unit 
-Replaced altitude  sensor with good unit 
-New fuel filter
-New line from bypass valve to  intake manifold
-Took bypass valve, spark plugs and wastegate frequency  valve from my B5 
S4. None of them made a difference
-Checked wastegate and  it moved freely, not stuck. The diaphragm is also 
free of holes
-The car  has no cats, they were gutted by previous owner
-I also disconnected the  catback just to be sure so I can say the car 
isn't choking from clogged  exhaust
-Took apart throttle position sensor, all contacts were good. I  also 
measured it and it checked out
-Tested hall sensor and it checked  out
-Tested RPM sensor and also replaced it with known good unit, which  didn't 
help
-Checked all teeth and timing reference sensors on flywheel,  nothing was 
amiss
-I believe I replaced the timing sensor too, which of  course didn't make a 
difference either
-Maf was tested by someone and was  told it checked out
-Checked pretty much every connector under the hood to  make sure it had 
the right values and no faulty wiring
-Checked wiring  leading to ecu, relays and fuse panel as best as I could. 
Didn't see anything  odd
-Did output test, everything was normal. I don't think the carbon  canister 
solenoid(or whatever it's called) was getting a signal though
-It  makes no difference if the car is hot or cold. It always runs the 
same,  sometimes it will start to idle very rough too and not really want to 
move at  all
-Cleaned idle stabilizer valve
-Tested air temp sensor, which was  fine
-All fuses are there and not broken
-Distributor has metal gear, no  teeth cracked or broken on it or the 
camshaft
-I noticed some arcing from  the distributor area one night while the car 
was idling, if I remember  correctly it was around the hall sender
-The temperature gauge isn't always  receiving a signal

My brother was in front of me  driving the car one night and it just 
wouldn't go anywhere(worse than before),  then he said all of a sudden(and I saw 
this), the car took off as if something  unclogged and it just pulled to 
80mph. After that it started bucking again and  never got "un-stuck" again. 
While I was behind him I saw a few little  bright red pieces comming out the 
exhaust. They looked a lot like bright  burning ash.

When the car hits that 4.5k limit, you  can hear a clicking in the ecu, 
like a relay. And the wastegate frequency  valve will frantically start 
clicking away too once you've let the gas go.  I've heard it under the hood quite a 
few times.

Anyways, I'm not sure what else I can say about all this....I'm sure there 
are  things I did which I forget. If I recall something else I will post it 
on  here. Or if you have any questions about a particular part you didn't 
see  checked, let me know.


Do our  cars have this issue at all? This is something about a 4k cutoff 
due to faulty  brake light on intended  acceleration:

http://www.intendedacceleration.com/tip_2.html



And lastly, here is the video I recorded. It shows exactly what my car is  
doing:

http://www.youtube.com/watch?v=STydKk6Ja28


Thanks  and sorry about the long e-mail. I just tried to include everything 
before I'm  asked what I've done to diagnose this  :)

Dan
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