<86-88 5KCSTQ> Re 2: 3000 RPM Wall (Long)

[Dave Head <dhead@sundial.sundial.net>]

At 05:03 PM 3/6/96 -0600, you wrote:
>
>Hi Dave. My 87 5KCSQ has developed a similiar problem possibly. During 
>acceleration , while my boost maxes at 1.2 bar, at 3.5 to 4k RPM my power 
>maxes out.  This appears to be a recent development, and I was to suspect a 
>bad sensor input to the engine controller ( either O2 or temp) but now I am 
>wondering about the cat.  Is there any good way for an owner to chek this 
>w/o disassembly?  I would like to direct the local mechanics to the problem 
>before getting a 2nd mortgage...PS mileage @ 112K.

I believe that some places can 'sniff' test it (this is getting out of my
league).  Try calling Midas - They may do it for free.  Remember - once your
boost maxes out - the wastegate opens and power flattens too. Plus your
knock sensor will start retarding the engine. 

Now that I'm running 1.7+ boost I HAVE to run premium. Tried 87/89 octane
and I could feel the retard kick in at the slightest bit of 'death rattle'.
Sure, I could stay off it - but I lusted after a tq for 10 years - now that
I've got one, I DRIVE IT! I love these 'ripoff' complaints about gas
companies telling people they need premium - any car with a knock sensor
loves the highest octane it can get...

I posted the diagnostic codes the other day to Preston, along with the
procedure - do you need them?  If you have a bad sensor, it'll tell you. One
of my early problems (my 87 was a mess when I bought it, and I'm still
straightening it out) was a broken lead on the inlet temp sensor - that
alone will retard your system. I still feel a flat spot around 3500 if I'm
not in WOT (60% duty cycle).

You can get a mediocre to good digital volt-ohm meter for about 40.00 from
Radio Shack and check you 02 sensor. It has to have a 10 megohm input
impedance to prevent damaging the sensor.  Read it to ground after starting
the car - it should steady out around 5-600 millivolts within 2-3 minutes.
Slower response to throttle changes as it ages. Then with a cheapo dwell
meter, you can check the duty cycle - connect at the little offwhite
connector by the wastegate that you never could figure out why it was there
before.
Sometimes your microswitch 'box' on the side of the throttle body acts up.
When you go wide open throttle (WOT) it should kick the FI to open loop rich
(60% duty cycle). You could have a problem there, too.  The WOT switch is
easy to clean/adjust. The other one will break yer spirit...

WRT yer other post - you get everything posted to the 'group', plus private
mail. In other words, if I reply to you and CC: or TO: quattro also, you get
a double post of this.
********************************AUDI FAN******************************
EMCM(SW) Dave Head
87 5KCSTQ 170K miles and counting...
1.8 bar boost - @ 1.3 the shuttle launches
Maitland FL
**********************************************************************