I would focus on 4 main things. This is what I would focus on if it were me, and they were all mentioned:
1) Look into your coolant temp sensors. Your needle may be saying one thing...but your ECM can be seeing something else. Research what temp it is supposed to be for the B6 (I don't own a B6), and see if it is in spec. If not, replace it. This has to do with your fueling calculations, and your symptoms match that when they are bad...such as the car not starting all the time. But not so much with the ignition coil blowing constantly on cylinder 4. Could be related...could be unrelated. We'll take this steps at a time.
2) Your crank position sensor could also be the issue. This item is hard to test without just swapping out. But you can take it out, see if it has metal shavings on it (it is a big magnet that senses crank position by gaps in the tone ring on the crankshaft), and clean it off it does. I would actually try this first and soon (like...right after you read this post if you have the time), because it is free. Take it out and clean the crap off the magnetic part. ECM uses this for ignition timing, which could also be why your car won't start and misfires. If too many shavings, ECM is basically confused and won't start the car. We will hold off on ordering this right now, while we test other free fix-its in the mean time.
These sensors suck because it isn't necessarily a work one day and not the next item. It will make your car doing "exactly" what it is doing now, then one day it will give you a DTC and then it will give out on you. How long it plays tricks on you till it givers out...never know. It can also just give out immediately. Very highly cause of your issue, so try taking it out and inspecting for shavings on the then. Wipe the end regardless and place it back in. Very tiny shavings eventually accumulate onto it, and that can most def be causing your problems.
3) Extra resistance can be created by corrosion for cylinder 4. Resistance makes the amp draw of the ignition coil more than it should be, making it more hot. Next thing you know...it burns out. Peel back the rubber boot on the engine harness side and look for anything that is a short (ie corrosion, wires exposed, etc). Not sure on the 30v, but the 20v has 4 wires. Two will be ground, one for each positive wire (4 in total). One is a constant 12v when key in starting position or car running. Other is a 5v signal. We will confirm proper voltage later if these have the same wires and voltage as the 1.8T 20v.
4) Not mentioned but could also be the culprit is the cam position sensor. Car will run, but sometimes takes more cranks for this to happen. But car will run on the 20v totally unplugged (confirmed this myself before). Apples to oranges because different management systems and engines, but taking a stab in the dark.
You also need to know that as you are turning the engine with no engine start, you are also flooding the cylinders with gasoline. So if the car won't start after multiple turns, your spark plugs are already saturated and they will need to dry before trying again. I would conjecture this happened without you knowing, but still is not the main reason of your issue. More like a domino effect that needs to be addressed.
I tested airing out the plugs on my car before with gas to the floor (2001 AWM) and it does not work. Car started and RPMS flew up with an unexpected start of the engine (yeah, wasn't happy with results when car started...lol). To air them out (dry them), undo the injectors (or fuel pump...but you still have all that fuel in your feed line. undo injector connectors preferably) and turn the engine. The intake air will pass over them without fuel spraying and dry off your spark plug. Then start over with plugs dry and able to create a spark for the engine to start.
If you don't have money for the full version of Ross Tech software, you can download the Torque app on your cell phone. I used this all the time. Then get a bluetooth OBD II reader to use it. It will cost you $20 max all said and done, and can be done for half that if craft. What will cost the most is the Torque app (don't use lite, and pay for the full version) and is like $5 or so. But it is well worth the money. You can use this for diagnosing of your coolant temp and such. You can actually use it for most of your diagnosing. I have the Eurodyne Suite and had VSDS before that. When I switched to the Suite, I sold my laptop with the Ross Tech software. Even though I have Eurodyne Suite, I find myself using this Torque app for just about all things that require fault code scanning and parameters that it is capable of reading. It can also be used on all cars, which is a plus (I use this for friend's cars when necessary, along with my back up car).
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Originally Posted by EuroxS4
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