V8V engine revs on cold start up
Discussion
Evening all.Yes I'm back with a question having only had my first Aston for nearly a week.
I've noticed that when starting the car from cold the engine revs to about 1500 RPM, and seem to stay like that for quite a while. If my car was a flappy paddle type I guess this might be a bit of a problem. And as mine is not. Is this reving normal ?
Dave.
I've noticed that when starting the car from cold the engine revs to about 1500 RPM, and seem to stay like that for quite a while. If my car was a flappy paddle type I guess this might be a bit of a problem. And as mine is not. Is this reving normal ?
Dave.
BravoV8V said:
Yep, sounds pretty standard.
These slightly higher revs can also lead to the clutch taking some abuse when reversing (with the corresponding smell). You'll get used to it (until you get a twin plate clutch fitted).
I thought I was the only one with a smelly clutch!! phew!! These slightly higher revs can also lead to the clutch taking some abuse when reversing (with the corresponding smell). You'll get used to it (until you get a twin plate clutch fitted).
DAVIDOXE said:
Mine too assumed it was just the choke.
Choke, you must be old like me 
, I remember these, especially the manual one on my first Escort. Fuel injected cars don't require this device as the ECU makes the change to the air/fuel ratio for you rather than relying on a piece of metal in the airflow to change the mix.Cockernee said:
DAVIDOXE said:
Mine too assumed it was just the choke.
Choke, you must be old like me , I remember these, especially the manual one on my first Escort. Fuel injected cars don't require this device as the ECU makes the change to the air/fuel ratio for you rather than relying on a piece of metal in the airflow to change the mix.
The raised / fast idle is normal
Besides one DBS around Rockingham, here is a link to the most boring video ever published...
https://www.youtube.com/watch?v=J0kvZ9yRecg&fe...
from cold start revs will be @ 1500 rpm for about 25 seconds.
it then takes a total of about 3 minutes (without moving) for idle speed to return to normal, about 750 rpm
The reason for the fast idle is to put heat energy into the exhaust gas / manifold after cold start to react with the secondary air supply injected into exhaust port which is needed to get the catalyst as hot as possible as quick as possible to convert harmful gas into less harmful gas and pass emissions. The reason why V12 does not behave the same way (exactly / for as long) is because the V12 has catalysts closer to the engine than V8 therefore doesn't need as many tricks to get the cats converting harmful gas into less harmful gas
yes, the downside of this trick is that the elevated idle speed is not a friend of the single plate clutch, but this scrabble to pass emissions commands the situation because is needed to sell the car.
Besides one DBS around Rockingham, here is a link to the most boring video ever published...
https://www.youtube.com/watch?v=J0kvZ9yRecg&fe...
from cold start revs will be @ 1500 rpm for about 25 seconds.
it then takes a total of about 3 minutes (without moving) for idle speed to return to normal, about 750 rpm
The reason for the fast idle is to put heat energy into the exhaust gas / manifold after cold start to react with the secondary air supply injected into exhaust port which is needed to get the catalyst as hot as possible as quick as possible to convert harmful gas into less harmful gas and pass emissions. The reason why V12 does not behave the same way (exactly / for as long) is because the V12 has catalysts closer to the engine than V8 therefore doesn't need as many tricks to get the cats converting harmful gas into less harmful gas
yes, the downside of this trick is that the elevated idle speed is not a friend of the single plate clutch, but this scrabble to pass emissions commands the situation because is needed to sell the car.
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