MC2 misfires

[Adam Gratz]

Dag-

You are running a higher rate wastegate spring, nothing else has changed, right?
I suggest before you go crazy, you reinstall the original wastegate
spring and see if the issue resolves.Then re-examine the simple things
first:

Is oil leaking onto the plugs?
Is that really the original valve cover gasket from 1990, or did the
last guy smear orange silicone everywhere?
Are you running the correct Bosch plugs? Re-gap them. Next, re-gap
with an actual gauge. Did you put way too much anti-seize on them?
Look at the doorknobs around your house. Do they all have anti-seize
finger prints? Clean that too. Clean the oil from the plug seats and
threads at the head. Use a hose and some dish soap to do this, don't
worry if water get in the cylinder, it will improve your performance.
Torque them to spec with an actual torque wrench.

Also, just for fun, remove and clean your block and body ground
points. You'll be surprised.
I know these things are boring, but do them anyway.
I have spent to many hours chasing high boost misses that ultimately
end up being plug related. A poorly grounded plug may only miss under
boost. It's fun reading schematics and unplugging harnesses, I know,
but cheaper to stabilize the basic variables first. Common things
happen commonly.

My 2cents

Doc-
'91 TQA with 034efi and 2bennet mods (and now a real rear window!)
'87 bmw 325 ic with straight pipes and a sexy Italian babe :)
'96 MBZ s600 (propane anyone?)
'80 MBZ 300 TDT veggie oil burner
'88 Cheby Subburban with Cummins 6BT motor (Veggie oil)
>

>
>> 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 B?sterud
> Norway
>
> 1990 Audi 100 TQ Sport Quattro

>