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Discussion Starter · #1 ·
Yesterday when I started my car (Mk5) from cold the choke came on as usual holding it at around 1200 revs, then gradually dropping down to around 500 revs when the choke is going off.

But today when I started my car from cold, It was as if the engine was warm the choke didn't come on, the engine fired straight up at 1000 revs and dropped straight to around 500.

Any ideas what might be wrong ?

Thanks,

Adam
 

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Discussion Starter · #3 ·
it normally comes on every time if i haven't started all day, and not sure on ambient temp was quite cool this evening.

water temp gauge was at 0 too


Adam.
 

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A choke is a restriction in the air intake that restricts air flow and richens the mixture to aid with cold start. Modern fuel injected cars don't have them and the R32 is no exception.

Based on the ambient temperature the ECU will richen the mixture to aid cold starting and sometimes the tickover is increased to 1,200 rpm for a short period
It doesn't happen everytime and don't see it as something to worry about.
 

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Discussion Starter · #5 ·
Fair enough, maybe its me, it;s just the first time its happened during my ownership

Thanks

Adam.
 

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A choke is a restriction in the air intake that restricts air flow and richens the mixture to aid with cold start. Modern fuel injected cars don't have them and the R32 is no exception.

Based on the ambient temperature the ECU will richen the mixture to aid cold starting and sometimes the tickover is increased to 1,200 rpm for a short period
It doesn't happen everytime and don't see it as something to worry about.
Didnt know that's what a choke was. I remember my Mum and Dad had a car with a black handle on a metal pole that you would pull out of the dashboard. After the car had warmed up a bit you'd push it back into the dashboard. That's my only knowleledge of a choke. Are you saying that a choke restricts the air into the engine so the mixture has a higher fuel content? If so why does this increase the rpm? Is the increase in rpm a side effect of the restricted airflow?
 
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I've owned my MKV 2 years and mine always starts at a higher rpm and then drops. Only time it doesn't is if the engines warm

Didnt know that's what a choke was. I remember my Mum and Dad had a car with a black handle on a metal pole that you would pull out of the dashboard. After the car had warmed up a bit you'd push it back into the dashboard. That's my only knowleledge of a choke. Are you saying that a choke restricts the air into the engine so the mixture has a higher fuel content? If so why does this increase the rpm? Is the increase in rpm a side effect of the restricted airflow?
The good old days, when at the first junction in the morning you had to carefully balance the choke along with the throttle to stop the engine cutting out but still be responsive enough so you can pull away. The manual chokes were replaced with automatic chokes which were a nightmare.

This explains it better than I could

http://en.wikipedia.org/wiki/Carburetor#Choke
 

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There was a thread about this in Performance and Technical recently.

Apparently it's normal. Below 14 degrees ambient, the Secondary Air Injection doesn't come on and therefore normal idle speed resumes. Which are ~ 1100rpm < 0 deg water temp, ~ 1000 @ 0 deg, ~ 750rpm >10 deg and 680rpm 10> deg.

And the natural idle speed is 680rpm, not 500 ;-)
 

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The good old days, when at the first junction in the morning you had to carefully balance the choke along with the throttle to stop the engine cutting out but still be responsive enough so you can pull away. The manual chokes were replaced with automatic chokes which were a nightmare.

This explains it better than I could

http://en.wikipedia.org/wiki/Carburetor#Choke
Thanks
 
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