Just wondering if someone could shed some light on a hard start when up to temp in our 07' R56S. The car starts great cold but when I drove it today for about 10 minutes shut off for about a 2 minutes started okay. drove again for again about 10 minutes sat for about 5 and when I started it it didn't jump to life but rather had a bit of a low idle a few seconds. Got home and thought I would give it a try after 5 or so minutes and it would start for about 4 seconds and putter down to nothing. Tried it 3 or 4 times and same results. Giving it throttle makes no difference. I did do this to me previous but after a long drive and the third time we stopped it would have the same behaviour. I simply walked away for 30 or 40 minutes and she would start rite up. Same as today half an hour later started great. Never a problem when running. to me it does seem like its running out of fuel or a vapour lock type situation. No codes and purge valve working as it should. Just thought I would put it out to the experts and see if this a common issue with the N14 and possible solution. Thanks all.

 

Common I don't know but the behavior suggests a bad fuel pump. ('course, I have to add this assumes the tank level is not down the fumes level...)

I'm not a fan of just throwing a fuel pump at the behavior. I can guess with the best but I still like hard evidence (in this case) the fuel pump it the problem.

Trouble is with the intermittent untoward behavior this makes it harder to check/monitor fuel pressure to see if the engine behavior is concurrent with low fuel pressure.

 

Well I may have found something. Just decided to bleed the cooling system on a hunch and got some air out of the bleed screw. Took it out 3 more times and each time air. Coolant tank level was elevated but went back to level when bled each time. Coolant does smell a bit funny, and I do suspect exhaust in the system. No sign of coolant in the oil nor any white smoke out of tailpipe. I am familiar with head gasket failures, but generally coolant and oil like to mix. One thing I’m not familiar with is the water jacket residing in the turbo being a possible problem. I’m guessing with that much air/exhaust in the cylinder head it could possibly be exactly that, vapour locking. Thoughts?

 

I thought about a cylinder head leak after reading your original symptoms. Coolant spritzing into cylinder(s) shortly after shutdown likely makes short dwell time start-up difficult but resolves after the engine cools and vapor pressure drops over extended periods. Now that you've seen a coolant level correlation, I recommend a head gasket replacement. Because the cylinder head gasket replacement requires the removal of the turbo and its oil and water lines, everything can be checked/repaired along the way.

 

For a suspected head gasket or cracked head leak or any leak that could have coolant in the engine one step is to get a sample of engine oil and have it analyzed. Among other things this checks for the presences of anti-freeze compounds in the oil. There shouldn't be any.

For the coolant there are test strips which can detect the presence of combustion gases, what this carries like hydrocarbons, in the coolant. There shouldn't be any of combustion byproducts in the coolant.