Hey guys,
I have found a wealth of information on here, but unfortunately nothing that is helping with this issue.
I have a A4 B5 1.8t APU.

About 3 months ago for an unknown reason wouldn't start at the fuel station. After 5 minutes of trying it started and has been fine until about 2 months ago. For a period of 3 or so weeks it just wouldn't start intermittently.

Cranks fine, new battery, gets fuel but no spark. Runs and drives great when it is going.

Just a couple examples.
I drove around town for 2 hours stopping at various places and started perfect every time until my last stop and then wouldn't start. I tried on and off over a period of 45 minutes and eventually left the car there. And returned 3 times with an hour or so in between and the third time it started.

I'd go out after not driving for and wouldn't start, if I was lucky after 5 minutes of trying it would go, but as a general rule it wouldn't start for an hour.
Or it would start fine and I'd drive 5 mins to a friend's place turn it off for a minute and it wouldn't start.

Then for a month it was perfectly fine. And suddenly it's happened again. Started fine this morning, replaced the o-ring on the coolant temp sensor and now it won't start.

Since it first happened i've cleaned cam sensor, engine speed sensor. Removed and reinstalled CTS, swapped ICM and coil packs out of my other A4.

No codes come up, but when it's not wanting to start, on my live data feed my TPS sensor stays on 4.3% and will not move with the pedal.
No spark when it's playing up either.
Engine gets plenty of fuel.

Car runs and drives perfect, and doesn't miss fire or get hot or anything.

Any help is muchly appreciated.

 

You replaced the o-ring ON the coolant temp sensor or the o-ring AND the coolant temp sensor.

Intermittent no-starts are very often attributed to bad coolant temp sensors.

Any other codes?
What about crank position sensor? Is that engine speed sensor? I know there's like 3 names for one part.

 

My money is on a faulty crank position sensor or the sensor within the throttle body. I have had issues with both and both have caused similar problems as you have described. It would start and drive just fine, once the car has ran for some time it would simply turn off on its own or fail to start. Once its left there for a while it will eventually start. The issue for me seemed to be once the car got hot enough either the crank sensor or the sensor within throttle body would just stop reading correctly and would cause the car to either just randomly turn off or fail to start until it is cooled a little.

PS: by hot i don't mean car over heating, I mean just operating temperatures for a while, hot weather outside will also contribute.

 

Car ran fine yesterday and i replaced the passenger cv and the gearbox speedo ring and then wouldnt start so I replaced the crank angle sensor or engine speed sensor, the little sensor underneath the oil filter held in by one bolt runs up to a grey plug on the firewall.
And I also replaced the temp sensor looking thing right after the drive by wire butterfly. Still wouldn't start.

Went out this morning and still wouldn't start after 5 mins of trying. After letting sit for half hour it started fine and has been fine all day. Let it sit for an hour after driving and wouldn't start. So I replaced the coolant temp sensor and still won't start.

No codes are coming up in a regular scan tool. I have noticed the battery light on the cluster flickers when turning over. I tried putting another earth to the body and engine to see if that helps but it didn't.

When it's running, it's never died on me, hot or cold doesn't matter.

I'm so lost with it

 

Hi

Were you ever able to sort out your intermittent issues?