I bought a used 1999 A4 1.8T - Auto: the previous owner had upgrades like ECU - Turbo - INtake - intercooler etc but something screwed up and he converted everything to stock:
Now the problem is above 4-5k RPM it stalls...like missing etc I've checked everyhose for leaks but cant see anything obvious I changed
1) MAf
2) ICM
3) ECU
4)TB
( I have another 1999 A4 - so parts arent a problem)

there is sucking sound from the left side ( turbo / Intake) like its trying to suck extra air but im out of options;

and yea for codes only Missing Firing cylinder 1 and 3

Options remaing;
1) I also noticed it has green injectors vs black/blue on my other Audi could that be the reason?
2) Can a bad plug cause this? ( im changing them tommorow)
3) Fuel system?
3) Coils?
4) If Diverter Valve is shot could this be the prob?

what else ??

Change your plugs, gap them correctly. Clear the misfire codes. Then switch coilpacks from cyls 1 + 3 to 2 + 4, and see if you get a misfire code on cyls 2 + 4. If you do, those coilpacks need to be replaced. You can/maybe shouldorder a whole set of 4coilpacks to save yourself the trouble.

The sucking sound could be a vac leak... and if it is leaking long enough, you'll probably get a CEL for long term bank 1 too lean or too rich.

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Bogie
2000 A4 1.8T Quattro, Borla Cat-Back, STaSIS Coilovers, K&N Air Filter, Autometer Boost Gauge
Forge 007P, SpeedTuning ECU, VVME 6000K, 034 snub.

I had the same problem and changed all 4 ignition coils/coil packs. They are every easy to switch and i get them at the audi dealership for 32 each. (make sure you know your engine code)...mine's AWM

its .028 for the gap...Ill do coil change first

but the sucking sound is from or near the Airbox - where the intake tube goes in...

what about the DV

If your ecu is stock, gap to 0.032". Gap plugs to 0.028" if you have a flashed/chipped ecu and you boost around 16psi or more.

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Bogie
2000 A4 1.8T Quattro, Borla Cat-Back, STaSIS Coilovers, K&N Air Filter, Autometer Boost Gauge
Forge 007P, SpeedTuning ECU, VVME 6000K, 034 snub.

just thinking - Im hearing the sucking sound only when its missing....so this could be something like coils etc cause Im pretty sure there's no leaks... what really happens if the DV goes bad? (I have a spare from my other car)

ok ... im back.. changed plugs switched coils... same shit!!!!.... this is driving me insane!!... what now???

if DV is messed up would it do something like this? or Turbo screwed up?

??

Today I changed the Water Collant Sensor to...so Im really in a HOLE!! same fkn SHIT!

Find yourself a propane torch (don't light it ) and spray it around the engine while its running. If the idle shoots up there is a vaccum leak.
A cracked turbo manifold can also cause miss-fires.

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00 A4 1.8T

01 S4 for sale, PM for details. (sale pending!)