MC engine, Mac13 ECU, S. Africa

["Scott M." <scottmo@teleport.com>]

Gerard,

> Where do you get this information from? 

The US parts micro-fiche shows the MC engine production
numbers and the month when they were produced. I also have
a copy of the Audi Service Training publication called
"1989 Model Introduction" which describes the changes with
the dual knock sensor MC engine. This shows the different
wiring connectors I mentioned previously. I may be able to
send you a copy (I assume, I can mail something to S.
Africa). I also have a copy of the "1986 Model
Introduction" service information that I can send which
describes the single knock sensor MC engine operation. Send
me your address and I'll see what happens........

> 
> The 3-connector bracket is there. The other bracket you
mention,
> which I assume should be between the ignition coil (tiny
as it
> is) and the hydraulic fluid reservoir, is not there. So
this
> would indicate 1 knock sensor.
>  
> I looked, slightly forward and below the regulator is a
knock
> sensor with the red boot fitted. It is just before the
dipstick.
> There is no indication of another sensor, this is
confirmed by
> the missing bracket on the firewall. Would the other
sensor also
> be obviously visible?

You have the single knock sensor, as it is normally located
underneath the warm-up regulator as you described. 

"If" you had two knock sensors they would be clearly
visible on both sides of the warm up regulator. 

It is possible that the engine block etc. in your car is
the high compression MC version with the K24 turbo but is
only using one knock sensor along with the early MAC11 type
MAC13 ECU. The MB style engine in the UK also has higher
compression but uses one knock sensor and the MAC12 ECU.
The normal boost in the MB engine is 1.65 bar. I don't know
if the MB uses the K24 or the K26 turbo.....Phil Payne can
you enlighten us with this info?......

One additional thing to check is to pull off the inspection
cover in the right side foot well and look at the ECU. Does
the MAC13 ECU have one metal cover with 4 tabs that bend
over to hold the cover on? If the MAC13 ECU has one metal
cover as described above then it is based on the MAC11 ECU.

Or does the MAC13 ECU have two metal covers that use 4
screws on each side to hold them on? You may also notice
the aluminum center section between the two covers. If your
MAC13 ECU looks like this then it is based on the MAC14 ECU
which is used in the US with the dual knock sensor MC
engine.

You can remove the one Phillips screw in the front top of
the ECU that holds the ECU against the interior wall and
pull the ECU out for better inspection. You can leave the
hose and main connector attached when you do this. If you
have the early version with the metal tabs holding the
cover on, you can bend the tabs up and slide the cover off
to see what is inside. You should see a main circuit board
where the main connector attaches and a slightly smaller
sized board on the top ~ 3/4 the size of the main board.
Below the top board in the open area you should see the
pressure sensor with the hose attached.  The EPROM or PROM
is soldered to the top board underneath. You would need to
remove the 4 additional screws that hold the top board down
to see the PROM underneath.

If you have the later MAC14 type MAC13 with the two
separate metal covers you can pull the ECU out as well and
remove the 4 screws on the cover with the part number
sticker on it and see what is inside. The later MAC14 type
ECU's have the ROM down on the main circuit board. The top
board is much smaller about 1/3 the size of the main board.

You can also check the turbo on your car and see which one
you have, you need a small mirror on an extension handle
and a flashlight to look down at the small metal red
colored tag that is on the aluminum cold side housing. The
tag  is on the cold side housing that faces the exhaust
side turbo housing.  It is not easy to see down there at
all, but it can be done from underneath without removing
anything. It depends on the quality of your eyesight......

You should see  K24 or K26 along with some part numbers
stamped in the tag  The K24 housing is smaller than the K26
but if you don't have anything to compare it to that won't
help you much.

> So here is what things are looking like so far:
> 
> 	MAC13 ECU
> 	1x knock sensor
> 	no O2 sensor
> 	Engine number: MC 049 018
> 
> Odd, isn't it? If your guess is right with the engine
number then
> it would seem they're running the old system on this
thing I have,
> but with a new motor (and perhaps turbo) and ECU.

Well, they may have decided to use the single knock sensor
ECU with the non US models that don't use the O2 sensor,
although I would think they would have gone with the MB
engine like what is used in the UK. 

I have run my dual knock sensor MC engine with an earlier
MAC11 ECU for test purposes using a special adapter wiring
harness I made up that swaps some of the wiring and
disables one of the knock sensors. They might have just
used a different wiring harness on your car to do the same
thing along with different software code in the MAC13 PROM.


If you can find someone to remove the existing PROM and
download the code and then email Orin or myself the code,
we can take a look and see just what Audi was up
to.......changing the boost maps and overboost cutout code
on these is an easy mod.

> Ok, I'm going to put a few questions about connectors in
the
> engine bay that  are just hanging around un-connected and
I
> thought I'd pass these to you directly and see what you
thought
> of them. Basically, there are 3 connectors just dangling
in
> the engine bay and I can't figure out what they're about.
> About 3 months back I saw a 2 connectors lying next to
each
> other, they're of the round type with purple clamps to
hold
> them together, it looked like the purple clamp broke off
and
> the plugs became disconnected so I just stuck them
together.
> I couldn't tell if that made a difference. 

Well, there are many connectors that hang loose and are not
connected to anything in the engine compartment on the
Audis, I would not recommend that you connect them back
together unless something obviously has come loose and is
not working. Many times there are extra connectors etc.
that are used for different engine configurations or
different options that were not included on your vehicle.

Hope that helps
Have fun
Scott M.