Question:
Why do diesel cars start up Straight away in the cold?
Kingblag
2010-01-07 00:44:28 UTC
I have an 11 yr old diesel car and wonder why it is so reliable in the cold weather. she fires up Straight away and never cuts out when waiting at the traffic lights. my neighbours have a petrol car that's only 5 yrs old and they struggle to start theirs in the cold even though it has a new battery and is serviced yearly at the same time as mine. also i see petrol cars cutting out at the traffic lights and mine ploughs on through. why are diesels so much better than petrol?
Eleven answers:
antiber
2010-01-07 04:04:41 UTC
At petrol car, the important thing as the core is ignition coil and CDI or contact point at old car, and those are electric item. Electricity has sensitive problem with cold, the electron atom can move smooth on cold and at long distance the power will be less. Meanwhile diesel doesn't need those, the battery directly charge the hot plug, and the very hot plug is already heating the combustion chamber, this condition will make fuel easier to ignite. While on petrol, the combustion chamber heated when the starting is doing. The rest thing is depend on the filter. But diesel is more sensitive to air trapped inside fuel line and dirty filter. Both are better only if both are in good maintenance.
chewbaka87
2010-01-07 08:41:55 UTC
The reason diesels start better in the cold than petrol's is down to the fact that Liquid petrol will not burn it has to be vapourised first.When a petrol is hot the fuel from the injector is sprayed onto the back of the hot induction valve and vapourises instantly but if the valve is cold on start up the fuel doesn't vapourise and can cause flooding and that is why petrol ignition systems have to produce a spark over 40000 volts to stop plugs fouling from cold.Diesels have a hot spot in the cylinder(glow plug) to initiate ignition but also have hot air due to compression which makes the diesel explode(cos that's what diesel does,cause of "diesel knock") And once diesels are running fuel is metered very accurately as the air for combustion only meets the fuel once inside the combustion chamber.
Pit Bull
2010-01-07 02:26:18 UTC
A diesel engine only needs the battery to have enough power to turn the engine over for it to start. Because the fuel fires on compression only [no spark plugs] once it is running all the alternator has to do is run the lights, the heaters, and to keep the battery charged. Petrol-engined cars need to keep supplying electricity to the spark plugs on top of everything else and this puts a much higher strain on their electrical systems. A charging system and/or a battery that's not 100% will struggle to cope in the cold.
Mick W
2010-01-07 01:58:16 UTC
at zero degrees C a new car battery only has 25% of the power available at 20 degrees C, due to cold weather slowing the reaction, diesels have larger heavy duty batteries which overcomes this problem to a certain extent, most diesels also have heater plugs, that operate for about 30 seconds to heat the fuel squirted round it for cold starting, as diesel is far less combustible than petrol.

a lot of petrol cars rely on putting say 12 volts through a 9 volt coil to boost the spark while the starter is engaged, car electronics do not work reliably when the battery voltage goes below 12 volts, (normal battery voltage 13.6volts) this happens when the battery is struggling to turn the engine due to the heavy demand of the starter, in cold weather, hence problems arise, fitting heavy duty/diesel battery's would overcome this problem.
anonymous
2010-01-07 01:04:46 UTC
I didn't know that had something to do with diesel mine is petrol and about the same age but the battery has to be sharp especially because its automatic
anonymous
2010-01-07 01:08:03 UTC
In simple terms:



The combustion process for petrol is where the fuel is ignited by a spark.



In a diesel, the fuel is compressed in a hot confined space - making ignition more likely.
Fing'
2010-01-07 02:36:48 UTC
My petrol cars start up in the cold first time every time.



Nothing to do with the fuel but all to do with the state of the battery used.
anonymous
2010-01-07 01:48:28 UTC
a diesel takes out shoddy servicing.see a basic tune on a diesel is oil change, air filter and fuel filter.see the lack of primary and secondary ignition system? a diesels advance is set and doesnt change to speak of, no electronics adjusting it to compensate for bad maintenance.basically the diesel engine all but takes out the "human element",and "the real dumb idea to do that "phrase."
mcmahen
2016-10-06 03:22:18 UTC
hear to Grizz, The glow plugs are small electric powered heaters, they do no longer warmth the gasoline, and that they do no longer ignite it like a spark plug. in case you do no longer look ahead to the glow plugs, you will finally end up doing lots of greater advantageous cranking to get the engine began, which will drain your battery and take greater time than waiting for the plugs. some glow plugs might properly be broken in case you do no longer wait, then they do no longer artwork, the engine is much greater stable to start, and you have small bits of steel bouncing around interior the cylinders. turn on the change, permit the glow plugs artwork, and remember that persistence is a distinctive characteristic.
pinickity1
2010-01-07 01:50:49 UTC
The diesel in your car is preheated using the heater plugs , which gives a small advantage.
anonymous
2010-01-07 00:49:03 UTC
mines a 1993 diesel renault and it doesnt always start up straight away, most of the time though it does - I would imagine all new cars start up quickly though.



diesels are noisier though I think.


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