MC2 misfires

[urq]

Are you in communication with MTM?  I would hope that they would be
available to help you with your troubleshooting.

The first thing I would do if I were in a similar position would be to check
the exhaust oxygen while the engine was misbehaving ... I'd suspect the
engine is running lean because the fuel can't keep up.  You may also want to
verify the crank/cam/distributor timing.  On the WX engine marginal timing
on the Hall Sender can cause engine running problems at higher RPMs.  You
say that you have looked at the sensors ... have you looked at the flywheel
teeth and the reference pin?  As the RPM goes up the signals from the VR
Sensors can deteriorate to where something that is marginal at lower RPMs is
unreadable at higher RPMs.  

If you haven't done so already you may want to check out Scott Mockry's
website for troubleshooting info:

    http://www.sjmautotechnik.com

Good luck!
Steve Buchholz

-----Original Message-----

I have a 1990 Audi 100 TQ Sport Exklusiv with the MC2-engine - vin
L-117-450.
It has done about 142500 miles.

Over the last two years / 12500 miles I have replaced
all sensors, almost every vacuum/pressure hose thinkable, brand new Bosch
injectors,
brand new TPS and the fuel filter. I have checked the different fuel
pressures and they are to spesification. All ignition parts have also been
replaced with OEM-parts within this time period.

I have installed an ecu chipped by MTM. With this ecu the car managed 0,6
(1,6 on the computer in the dashboard). I then installed a stiffer
WG-spring. And now I've got the following problem:
If/when the car boosts 0,6 (1,6 in the computer/display in the dashboard)
and goes over 4000-4500 rpm, the car misfires badly. I'm quite sure it's not
fuel cut, because that feels like
knocking your head against the windscreen.

I've read fault codes, but the car reports "4444" = no fault found.

What could be wrong?

Any clues, hints or tips?

/Dag Bøsterud
Norway

1990 Audi 100 TQ Sport Quattro
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