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Warm Starting Problem


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Hey guys,

Wonder if i can pick your Lupo brains!!

Recently my little Lupo has been playing up and sometimes doesnt start after being used i.e. popping into Tesco's briefly then coming back out... The engine turns just doesnt fire..

The weird thing is it starts first time when the engine is cold...

It had it's 40k service back in Jan and has it's MOT on saturday... 2001 Sport...

If anyone can give me any advice that'd be fab :)

Snowball...

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make sure you buy NGK plugs as recommended and fitted by volkswagen themselves, not Bosch ones...

NGK Part number is "BKUR6ET-10"

NGK Stock code is "2397"

Why Al????????? :confused:

Edited by 1 Litre Screamer
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That sounds like either lack of fuel or a weak spark. Try changing the spark plugs and see how that goes. It is a fair amount of time since you said it was serviced.

Why would that only exhibit a problem when starting from warm? If it was fuel supply or spark, cold starting would also be an issue surely? It's worth noting there is a definite fuel smell when attempting to start from warm and failing, suggesting the engine is in fact flooding; hence I'd doubt it was a fuel supply issue.

Edited by Snowball
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make sure you buy NGK plugs as recommended and fitted by volkswagen themselves, not Bosch ones...

NGK Part number is "BKUR6ET-10"

NGK Stock code is "2397"

Just for the record, a few days ago I fitted those exact plugs to a 22,000 mile 4.5 year old 1.4, the engine is noticeably smoother after having the plugs changed! They are due for replacement at 4 years or 40,000 miles, whichever comes soonest.

Snowball: sorry that that doesn't really help you, but it might be a good idea to replace them if they are overdue anyway :).

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Why would that only exhibit a problem when starting from warm? If it was fuel supply or spark, cold starting would also be an issue surely? It's worth noting there is a definite fuel smell when attempting to start from warm and failing, suggesting the engine is in fact flooding; hence I'd doubt it was a fuel supply issue.

When the engine is warm or hot the fuel in the fuel rail heats up and turns from liquid to a gas. This is what is referred to as heat soaking. To ignite fuel in the combustion chamber when its a cold wet liquid requires a small spark, now change this liquid to a gas and the spark required to do the same function of igniting the fuel in the chamber has to be stronger. Now without going too far in to it the reason is simple, gases dont stay in the chamber longer enough to ignite. If you ever watch a hot race porsche engine trying to start you will see it takes ages before you see white fuel vapour from the exhaust that then cools the combustion chamber just enough for it to start, then you get huge flames from the expelled gas. So theres the reason! As for makes of plugs, well if the electrode length is the same and the heat range are within the same area then a plug is a plug. Dont be led by VW and their parts shelf.

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Well they've just called saying it's a coolant temperature sensor problem, £135 all in to replace it! Apparently if the sensor fails, the engine thinks it's cold, so floods the engine by over-fuelling. Obviously when it's warm, that causes the engine to not fire properly. Hopefully a useful search item should anyone else experience something similar in the future :)

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