3.6 CC. Cranking but not starting

[00100100]

Might sound silly, but long time ago I had a similar issue with a different car/engine. When the engine is warm it did crank with no start. Until it cooled down a little. Turned out to be a loose wire or bad connection point to one of the sensors.

[seanmau5]

After weeks of mild temperatures and no real issues, Sydney was 36 degrees on Wednesday and my CC was in the sun all day and sure enough...

YouTube

Got it on video finally..


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[tinto]

My 08 R36 did this too. Fine if it was very cold, but it would craaaaaaaaaaaank for a long time if it was a warm day and I'd driven it earlier.
I never got to the bottom of it before I sold it, but had a coolant temp sensor on order after doing a bit of reading.

Mine had that rough running occasionally too - really disconcerting - made me think it was timing chains etc

I wish I could be more help - Good luck with it.

[neil]

Ive had similar issues for years , but I have the jetta TDI , can go months no issues , then usually after long drive
and you stop but then shortly after need to start it , it will crank not fire , I just pump the accelerator while cranking
and it always fires up this way although doesn't make any sense to me why, I've just learnt to live with it.

[00100100]

Looks like one of two cylinders have been shut off. When you did the error scan, did you do that while it is in that rough idling situation? It should report which cylinders are off. Could be the carbon build up issue, similar symptoms to others who had to clean their engine valve head. Even though the carbon problem is usually when the engine is cold. Have you been using foam cleaner regularly?

[seanmau5]

Mine fires up if I pump the accelerator too, but unfortunately (or fortunately, depending on how you look at it) I’m not the kind of person that can just live with an issue like this. No I didn’t do a scan while it was running rough like that, because while I had the cord that I had borrowed, the stupid car wouldn’t do it. The day after I return it and bingo I’ve not used any of the foam cleaner before, but I did just buy a can of liquimoly that I’ll run through it this afternoon and then on Thursday I’ll remove the intake and inspect. I find it so odd that it’s only when it’s hot outside and based on the research I’ve done, this is a common issue that I refuse to pay VW a diagnostic fee to tell me there is ‘nothing wrong’


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[00100100]

Any updates on the situation?

[seanmau5]

Sort of. I definitely think it’s an evap or tank venting issue based on all my situational testing.

Plenty of warm days, I’ve left the fuel filler cap loose so it doesn’t create a seal and the car starts first time, every time. Also, check out this link. On warm days only with the fuel filler cap sealed this happens. Release fuel filler cap and noise stops.

YouTube

[seanmau5]

Spent a bit more time on this today.. Particularly focusing on the charcoal canister.

The venting noise in the video in the above post is coming from the pressure retention valve which connects the tank breather line to the charcoal canister. This isn’t an electronic valve hence no errors - I believe it works based on pressure and has a diaphragm in it that allows air flow dependant on this pressure. There are 2 soft rubber o-rings and one harder plastic o-ring inside the valve that don’t seem to be sealing properly and allowing air to be sucked into the canister past the seals and causing the noise.

Unfortunately I don’t believe I am any closer to solving the no start issue..

[00100100]

It is very odd indeed! Best of luck.