Audi 1.8T hard to start after stall ?

[Toaster Pilot]

I've found that if I stall my 1.8T A6 (the clutch has seen better days ) or it cuts out after starting ( the immobiliser is slightly faulty and doesn't always see the key) it cranks for a long long time before it will restart.

Anyone got any idea what might cause that? Never hard to start it any other time.

[MissChief]

I'd recommend putting a code reader through it. Could easily be a dozen things. Fuel pump, distributor cap, coil packs (which were subject to recall on nearly every 1.8t ever) spark plugs, cam position sensor etc etc.

[kambites]

Does what you do with the throttle effect it at all when it's in this state?

Is it firing at all while it wont start or completely dead until it suddenly springs into life?

My guess would be a temperature sensor failure (causing the car to constantly over-fuel and hence flood). Same effect as trying to start an old car with the choke out when it's hot.

Edited by kambites on Monday 12th May 21:55

[Toaster Pilot]

The temperature sensor was recently replaced with a cheap one and it under reads so i suspect you may be right....

[kambites]

What is the temperature sensor saying while you're trying to start it? Does the dashboard show coolant temperature it while the engine is cranking?

[Toaster Pilot]

Not sure if it does or not - I really need to set up my VAGCOM and see what's going on with the sensors I think

[kambites]

You might find the diagnostics port loses power while the starter is pulling 100 odd amps from the battery, in which case it wont help much.

It's not impossible that your cheapy sensor needs a slightly higher voltage than an OEM one to supply a reading so while the battery is supplying cranking current it stops reading completely causing the ECU to hugely over-fuel and flood the engine... or something.


ETA: Get it into this state, crank it for a bit and then take a spark plug out and see if it's wet.

Edited by kambites on Monday 12th May 22:27

[Toaster Pilot]

It seems to be improving as it works it's way through a tank of super unleaded (possibly it's first in 197k miles)..... Might be unrelated though.

Could the fuel filter be at fault?

[Toaster Pilot]

So I haven't been using it much and this problem has escalated quite badly - it just won't start now at all (but was fine for the past couple of days)

Left me stranded in need of recovery (AGAIN) last night because it just would not start - hot, cold, temperature sensor unplugged/not

Fuel pump relay, fuel pump, crank position sensor are my 3 suspects at the moment - need to actually dig out my VAGCOM this time.

[Toaster Pilot]

VAGCOM reports a fault with the camshaft position sensor

[MissChief]

Easy fix I believe.

[Toaster Pilot]

Changed it, ran fine, wouldn't start hot.

another DTC for Engine Speed Sensor now