Cold starting problem

[Caddy2156]

Hi 

audi s3 mk1 8l 

My car used to idle above 1000 revs on cold startup then drop to below 1000 revs after 1 minutes.it has now stopped doing this? Did have new inlet pipe fitted..and fuel filter.

If I leave car over 12 hours it doesn't start until maybe 4 to 5 turns and when started idles under 1000 revs

Once started it will start first time until I leave 12 hours or more..

No codes on ecu and engine management light is off

Any ideas what it could be??

Thanks 

 

Edited October 5, 2022 by Caddy2156

[Steve Q]

If there's no codes then it's old fashioned diagnostics I'm afraid. 

What condition is the battery? If it's old it might be worth getting this checked? 

Spark plugs/glow plugs when we're these last changed? 

Is it worth getting the starter motor looked at? 

[Caddy2156]

14 minutes ago, Steve Q said:

If there's no codes then it's old fashioned diagnostics I'm afraid. 

What condition is the battery? If it's old it might be worth getting this checked? 

Spark plugs/glow plugs when we're these last changed? 

Is it worth getting the starter motor looked at? 

Hi 

Thanks for reply 

Battery is good ,spark plugs and coil packs changed 2 months ago, no clicking from starter motor..

It doesn't seem to want to fire up straight away takes like 4 attempts then it will start.makes like a puffing noise for a few seconds then runs fine..and will start everytime after. until car is cold again then same problem starting.

Don't know if there's a sensor that could be affecting the starting problem? Or maybe a broken air pipe?

 

 

 

 

 

[JMKC82]

Hi,

When was the last service?  Engine oil okay, and correct grade?

[Caddy2156]

4 hours ago, JMKC82 said:

 

 

Edited October 6, 2022 by Caddy2156

[Caddy2156]

40 minutes ago, Caddy2156 said:

 

Hi 

Oil change is due 

Have been Topping up with 5w30 c3 ? Don't know if it could be oil as always use 5w30. But first time using this oil

Edited October 6, 2022 by Caddy2156

[Caddy2156]

28 minutes ago, Caddy2156 said:

Hi 

Oil change is due 

Have been Topping up with 5w30 c3 ? don't know if it could be oil as always use 5w30. But first time using this oil

[Magnet]

Hello David,

Oil associated?? I seriously doubt it. 
Not sure with your engine, but there is usually a coolant temperature sensor that monitors the coolant temperature, and signals the ECU to provide the correct mixture - obviously, a richer mixture for cold start. If this sensor fails, it usually does so to an ‘average mixture’ and obviously not rich enough for instant cold starts. Ok , no fault code, but I don’t have complete faith in the integrity of these codes. 
As an aside, and I may be blown out of the water with this, but RAC oil via. B&M and such outlets?? A nice engine deserves nice  oil. Treat it to Quantum - VAG approved at not much more, and delivered to your door from a variety of eBay sellers. 
Kind regards,

Gareth. 

[Caddy2156]

2 hours ago, Magnet said:

Hello David,

Oil associated?? I seriously doubt it. 
Not sure with your engine, but there is usually a coolant temperature sensor that monitors the coolant temperature, and signals the ECU to provide the correct mixture - obviously, a richer mixture for cold start. If this sensor fails, it usually does so to an ‘average mixture’ and obviously not rich enough for instant cold starts. Ok , no fault code, but I don’t have complete faith in the integrity of these codes. 
As an aside, and I may be blown out of the water with this, but RAC oil via. B&M and such outlets?? A nice engine deserves nice  oil. Treat it to Quantum - VAG approved at not much more, and delivered to your door from a variety of EBay sellers. 
Kind regards,

Gareth. 

Hi 

Thanks for reply 

I will look at replacing the coolant sensor and see what happens 

Many thanks

[Caddy2156]

Hi 

Have replaced coolant temperature sensor today and the problem is fixed. Happy days 

Thanks all.