Cold Start/Fast Idle

[Stormchaser]

When I first got the Rapid it used to idle fast on cold start (about 1200rpm) now it doesn't in any temperature. It just idles at 850 rpm like normal. Is there something wrong with it?

It's booked in to dealer on Monday to have the instrument cluster changed due to faulty fuel gauge. Should I tell them about this too?

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[Rednaxela]

The start idle on my polo with the same engine seems to do this too now and then. Haven't noticed it on the sport yet though.

[skoda1982]

Mine does this

[camelspyyder]

aircon on or off.

[Stormchaser]

It's cold start so no air con on.

The air con puts it Upto about 900 to 1000 rpm when engines warm.

This is its first initial cold start. The cars garaged all the time but was never a problem. Started at work last night at 1 degree outside temperature and no fast idle :(

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[mu7]

 During operation of the air conditioning, an increase in engine idle speed may occur under certain circumstances in order to ensure sufficient heating comfort

 

 

 

The cooling system only operates if the following conditions are met.

The cooling system is switched on.

The engine is running.

The outside temperature is above approx. +2 °C.

The blower is switched on.

 

 

The manual has many secrets

[camelspyyder]

Does your AC not start up in the previously selected mode then?

 

The idle speed is pretty random though - it only drops right down to 600 when the car is stopped.  Coasting to a stop has it up at 8-900.

 

And I did wonder about the random RPM on start-up like 1200-1300 but now I don't use AC so much it doesn't seem to happen.

 

 

 

 

 

 

 

The manual has many secrets

 

 

So cold start RPM can be less than hot - weird

[mu7]

AC draws current, so the engine has to keep up. If it's off because it's too cold outside, a lower idle speed makes sense. 

 

Heating is just a by product of the engine running. You could argue it should increase when it's freezing outside to get up to temperature sooner (and clear the windows faster!) but if there is less load on it when idle, it may as well relax a bit and save some fuel. 

 

As a side note, I've got climate control, I guess it behaves the same way as the manual system. I leave AC on, but it doesn't mean the system is running if it's decided it's not warm enough outside.

Edited 13 December, 2014 by mu7

[Stormchaser]

This isn't about Air Con though. Mine is off at cold start. It used to idle fast always but now it doesn't. Bit like back in the day of manual chokes.

I've got manual AC and not Climatronic.

I only use it when it steams up inside as the engine gets warmer. I'm just wondering why it doesn't fast idle on cold start in very low outside temps.

Does anybody else's do this?

I'll probably get the usual BS answer from the dealer [emoji57]

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[chrisgreen]

It's a curious one - my car has fast idled a fair few times at start-up, not every time and there doesn't seem to be any pattern to it (extreme cold etc). It is happening less often though. I don't think there's anything wrong with the car, but I don't have a defacto answer for it.

As it is reducing in frequency for me, i wonder if it's linked to the running-in process - the more the engine is run-in and loosens up, the less need there becomes for a burst of fast idle to get the car to operating temperature and condition.

Entirely speculation on my part, please don't take as gospel.

[Stormchaser]

Thanks Chris but strangely I was thinking the same. Started it tonight (in garage) at 10 degrees and it idled for a minute at 1100rpm. Parked out in the freezing cold (0 degrees) for a few hours and it started and idled at normal tickover speed. Strange.

I'll see if the dealer finds anything (haha) on Monday whilst they sort all the other things out.

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[_N_]

I've been looking at the same thing. Now in winter when I start the car it takes a longer time to get up to warm engine temperature than in summer (which is obvious).

I have AC turned off all the time, so it hasn't got anything to do with AC. If I start the car and I have the heater turned down to the coldest temperature, the car heats up faster and runs at lower rpm. I watched the water temperature needle rise as it's warming up and then I turned the heater up to the warmest and the water temperature went down (to be expected) and rpm increased.

 

So, to conclude, try playing with the heater temperature setting and engine rpm will change while the car is warming up.

[Stormchaser]

The outcome to this was no fault found. They tested other Rapids there and they done the same [emoji6]

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[chrisgreen]

The outcome to this was no fault found. They tested other Rapids there and they done the same [emoji6]

 

 

Fingers crossed its just a quirk of the TSi engine running in.

[Stormchaser]

Could be yes. It still runs fine when cold so I'm not really bothered.

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[Phil-E]

I think there are many different factors that can trigger a fast idle and it won't always do it.

 

If intake temps, battery voltage etc etc are within reason then it won't do a fast idle.

 

I'd be worried if it was doing it all the time.

 

Ours idled at 1100rpm this morning but a start in 0c temps the other morning gave an idle speed of 900rpm.

 

Phil