Car Won't Start (video inside)

[BlazinB5]

So I've been reading that the most common issue related to a car not starting, is usually either a battery, coolant temp sensor, or a fuel pump, but I am hoping this video should make it more obvious what the problem might be.

This car is a B5 Passat, but the Passat is basically a front wheel drive A4, with the same chassis, motor, and transmission. A new fuel filter was put in weeks ago, and car has been working perfectly until now. I could hear the fuel pump prime with the key in the on position, and the garage smelled like gas after attempting to start.

I figured I would ask here, since people are a lot more knowledgeable, and the info might help people in the future using the search feature.

https://youtu.be/5il0QyrJegE

[vrmm]

Well it's not the battery :p You could check for fuel pressure. With a gauge or pull a line off of the fuel rail and place it in a bottle that is secured. You should be able to just turn the key forward without starting it and have it spray. I've never had a bad coolant temp sensor stop my car from starting. I've left it unplugged and driven around for a long while before I realized it was unplugged.

[BlazinB5]

Well it's not the battery :p You could check for fuel pressure. With a gauge or pull a line off of the fuel rail and place it in a bottle that is secured. You should be able to just turn the key forward without starting it and have it spray. I've never had a bad coolant temp sensor stop my car from starting. I've left it unplugged and driven around for a long while before I realized it was unplugged.

I could be wrong, but I feel like the fuel pump is working, since when the key is in the on position, I can hear the fuel pump priming, and after cranking, the garage smells like fuel.

[vrmm]

Have you checked for codes?

[BlazinB5]

Just held the gas pedal down while attempting to start it, and guess what, the car started right up. Holding the gas pedal down while cranking the car disables the fuel injectors, allowing you to clear the cylinders of fuel. Any ideas why it would work after doing this?

Edit: completely forgot to add, but I disconnected the battery for 30 minutes, therefore I resented the ecu and everything, before doing what I did (hold down gas while cranking).

[walky_talky20]

Yes. "They do that sometimes". I think it might be some kind of software issue, or a momentary bad reading from a sensor (like a coolant temp sensor) that causes the engine to flood out. Could even be sticky valves or some other reason that caused momentary low compression. Anyway, even after it normalizes, it needs a little more help recovering than just extra cranking. The clear flood mode clears it out and lets it start.

Indeed, my own car has done this entirely out of the blue. It was in the shop overnight for a brake job. Finished it up the next day, went to crank it and it did the same thing. Almost started, then just cranked. I had done literally nothing to the engine - not even an oil change. Held the pedal down and it started right up. My theory was a momentary bad CTS reading that caused an overly rich startup attempt.

[Wrath And Tears]

According to my coworker who was a VW tech when our cars were coming out, there's some glitch in the ECU that cause occasionally cause the car to use way to much fuel. It tries to do a super cold start fueling or something. VW/Audi knew about it but it also happened so rarely they figured whatever. That glitch could easily be something like walky described.

[walky_talky20]

Interesting info about the software glitch. Makes a lot of sense, because my CTS had been rock solid both before and after that day. Still running the same one, actually. It was really weird, and hasn't done it again in at least a year. I think it definitely has to do with the value for coolant temp (nothing else can make it go that rich), but a glitch with the handling of that variable makes the most sense.

[BlazinB5]

Interesting, thanks for the good info guys. I would've never imagined that my car possibly flooded out this entire time, but the idea that the coolant temp sensor possibly gave a bad reading (the glitch, perhaps) would make a lot of sense. I've had several people tell me replacing the CTS fixed their problem, but it sounds like these people could've possibly solved their issue by holding the gas down all the way (disabling fuel injectors) while cranking - assuming that their cars only symptom is that randomly wouldn't start.

I'm beginning to wonder if a new CTS would've solved my problem? If I didn't know about the "hold the gas down" trick.