How do chokes work?

GlasgowTitan · 12 Feb 2007 at 18:55

I remember as a kid my dad's old cars used to have a choke and when starting up in the mornings it had to be pulled out or we be going nowhere. I take it nowadays cars have some sort of automatic choke, or the engines have evolved so that they aren't needed..? I know if I had to drive a car with one I wouldn't do it right

Enfield · 12 Feb 2007 at 18:56

Mine has a manual choke.

Basically you need to use it when it's cold. You pull out the choke which in turn moves the butterfly in the throttle body to stop the air getting into the carb (depends how much you pull it) so it runs rich thus idling at a higher rpm and not stalling.

Diesel · 12 Feb 2007 at 18:59

The one in my old Uno was great. Wouldn't start without the choke, but if you pulled it out for more than 5 seconds it would flood the engine.

-Mike- · 12 Feb 2007 at 19:06

I'm not sure the exact workings of the modern day injection car but I'd imagine fuel mixture would be richened in a similar way to what the old choke did - just that you don't have to don anything now. My XR2 had a supposid auto choke - blasted thing never worked so it was always a bit of right foot manipulation

GlasgowTitan · 12 Feb 2007 at 19:11

ok its kinda making sense now, beacause in the mornings Ive noticed that my zetec engine idles at about 1500rpm, then when i get to uni its idling at about 700rpm or something...

Guigsy · 12 Feb 2007 at 20:17

Hehe, only reason my old Metro didn't get nicked on a cold January night was the scrotes didn't know what a choke was. They hot-wired everything and got the starter motor grinding no problems... It would start in less than a second with a touch of choke, no chance without it.

Chronos-X · 12 Feb 2007 at 20:47

My 205 has one - you spend weeks of stalling and flooded engines to work out how much it should be out at each stage of the journey :rolleyes:

Dup · 12 Feb 2007 at 21:30

Chronos-X said:
My 205 has one - you spend weeks of stalling and flooded engines to work out how much it should be out at each stage of the journey

My girlfriends 1992 1.1 Metro has a light that tells her when to have the choke out and when to pop it back in

Dr Who · 12 Feb 2007 at 21:34

Nowadays the fuel injection handles the richening up...

If you flood an engine (carb) with a choke, turn choke off, hold foot flat on floor and crank til it starts..

DO NOT pump throttle as it catches, as the accelerator pump just throws wodges more fuel in...

Release the throttle once the engine revs up cleanly

pinkaardvark · 12 Feb 2007 at 22:30

FI isn't necessary nor is an ECU, my old 12V carbed toyota corolla had an auto choke

-Mike- · 12 Feb 2007 at 23:41

My XR2 apparently did also, not that it worked.

-Mike- · 12 Feb 2007 at 23:41

Dup said:
My girlfriends 1992 1.1 Metro has a light that tells her when to have the choke out and when to pop it back in

Err, are you sure?

thedazman67 · 13 Feb 2007 at 00:29

My first car had a choke used for when starting from old, restricts air entering the carb making the engine run rich. once the car has been running it would be fine.

With my old car i found i only needed to use the choke once in a day maybe twice in winter, to start the car i would have the choke fully on, soon as the car started i'd put it down to half, then after about 5 minutes i'd take it off completely it was then the engine was warm enough to sustain itself.

thedazman

Sone · 13 Feb 2007 at 03:04

-Mike- said:
My XR2 apparently did also, not that it worked.

i had a 1.6 escort (cvh carb) and it too never worked

Man did i hate that car

THE CHOPPER · 13 Feb 2007 at 03:13

I tend to use the sleepeer or go for the full two hands round the neck veins popping out of my head red face slightly psychotic grimace technique

Hawk Tuah · 13 Feb 2007 at 09:52

My GSXR has a choke. Its very easy to flood the engine. Takes a bit of playing with to start it right on a cold morning.

Dr Who · 13 Feb 2007 at 12:51

Bug One said:
My GSXR has a choke. Its very easy to flood the engine. Takes a bit of playing with to start it right on a cold morning.

If the bike is working right, you should just pull the choke full on, and crank without touching the throttle at all..

Most problems on bikes are down to not using full choke and winding the throttle up and down...

:cool:

Guigsy · 13 Feb 2007 at 12:55

Dup said:
My girlfriends 1992 1.1 Metro has a light that tells her when to have the choke out and when to pop it back in

My 1990 Rover Metro 1.1 c (c = no cig lighter, nearside mirror, radio or full height rear bumper) just had a light to say the choke was out. You sure it's just not a dodgy bulb?

Hawk Tuah · 13 Feb 2007 at 13:26

Dr Who said:
Most problems on bikes are down to not using full choke and winding the throttle up and down...

** that'd be me then.

It does depend on how cold it is though. Full choke isn't needed when its not really cold.

Dr Who · 13 Feb 2007 at 13:46

Bug One said:
** that'd be me then.

It does depend on how cold it is though. Full choke isn't needed when its not really cold.

Thats true, but best to use full choke to start, and then back it off as soon as its starts to retain a fast idle until it is warm...

Dont worry about being guilty of "mis-starting" I have seen MANY very experienced bikers do the same and then moan that their bike floods...

Of course with FI now, the choke is no more than a fast idle