Car didn't want to start... then did! :Confused:
 

Interesting fault today.
It was a warm day today, about 32°C.
My car had been parked at Ringwood in the sun all afternoon when I jumped into it about 7:15pm (still 28°).
I then drove it to Upper Ferntree Gully, around 13km (8 miles) to go shopping on the way home.
The car got well heat soaked during the trip and had noticeable drag and noise from the engine fan.

It was about 15mins by the time I returned to the car.
And it decided it didn't want to start!
It turned over fine, all lights on the dash extinguished as normal, but it would not catch, or even stumble.

No immobiliser issue, those lights went out fine (and it wouldn't start at all, the immobiliser starts and stalls).
No CEL.
I haven't scanned it yet.

I opened the bonnet and performed an obvious fault scan, and checked the vac hoses (they're on the replacement list). Nothing obvious there.
Superficially checked power connections, everything was fine.
Tried to listen for fuel pump priming, but couldn't hear it (the current pump is about 5 years old).
Plenty of fuel, oil, coolant.

Turned it over one last time from outside car to listen for injector firing when it immediately started.

Drove completely normally the rest of the way home (8km/5miles largely up hill).
Tested a restart once home - started normally.


So any ideas?
Fuel pressure regulator was renewed when the pump was replaced (5 years).
Can the fuel pump relay behave badly in hot weather?
Anyone had other heat soak issues? CPS for example?

Appreciate any ideas. Its only getting hotter for the next 8 weeks!

Jeez. I think I'd refuse to start in that heat too. Even the British summer gets too warm for me.

It does sound like an electrical fault, considering that it started normally and effortlessly afterwards. A sticking relay would be my guess.

That does say CPS to me - its quite common for that to cause hot-start issues across many models. We had the exact same thing in Lucy's TT where it just randomly wouldn't start from hot from time to time and you had to give it several goes. No faults, and tellingly, no RPM showing in VCDS when it wouldn't start.

Its simple enough to change in the D2. Pop the left driveshaft out and disconnect the headlight level arm from the sensor for better access and then remove the driveshaft heat shield from the gearbox. The only niggle is the small heat shield on the engine behind the downpipe as the factory wiring has a cable tie behind it. With the shaft off you can remove the heat shield (1x M6 bolt), snip the tie, and remove the sensor. Worth soaking the CPS bolt with your penetrating oil of choice since sometimes it can seize in to the gearbox. Unlikely down under, but quite common here. If it snaps you have to take the gearbox out!

Yeah, I was thinking its CPS behaviour. Seen this fault before in Commodores.
Not to rule out the relay, but the fact it played up after running nice and hot and stopped for a short time, then once it started was again faultless, I'm thinking CPS.
It also started flawlessly this morning, and without the hustle and bustle of the supermarket carpark (and nearby main road) I was able to hear the fuel pump prime and the low pressure return to the tank before starting.

Would I be right in guessing the CPS wouldn't throw a code?

It's going to be 36°C today, though I'm only driving to/from work, which isn't very far. So the engine will be cold (!). If it plays up under these conditions, I'll swing more towards the relay.
If its faultless, I'll keep thinking CPS.

Correct - no code for the CPS. If there's no signal then the ECU just assumes the engine isn't running.

I've ordered a CPS just in case.

Got some catch up maintenance to do over the next month;
Timing belt, brake pads and fluid, control arms, general service... so I can probably fit it in during the suspension work.

Been flawless since.
36° yesterday was followed by 38° today, but I've only driven to/from work, so cold starts only.
Will have to see what happens next time a hot start is required...

'Cold starts' when it's 36 degrees! I know what you mean by it, but it just sounds weird. +++

Nah... 36° is just getting started!
38° was pretty hot though!

If I send you a plastic bucket would you return it with a sample in it?