My Wife thinks I am a fusspot for insisting on only starting the car if I am going to drive somewhere.  However, a few days ago I came home late with a heavy load, so it had to be dealt with the next day.  This involved a cold start ( 5 degreees C) backing out of the garage for 25 yards to a convenient spot, unloading and then restarting and going another 25 yards back into the garage.  I followed up with a token 30 seconds or so of idling before switching off.

 

Next day (5 degrees C again), it refused to start....  Despite a good battery it felt like the starter was struggling to turn it over.  I then remembered the same thing happening years ago in similar circumstances.  The solution is to hold the throttle pedal fully down whilst operating the starter.  This time after some churning it fired up and cleared, with a brief puff of grey smoke from the exhaust and a smell of raw fuel.

 

Since then, it's all completely back to normal and starts immediately every time as usual

 

I can only assume that this is due to the spark plug insulators absorbing fuel vapour overnight, or maybe the catalyst getting loaded with unburnt fuel or condensation from the previous cold starts and thereby choking the exhaust.  Maybe the ECU has a "clear flood" mode if you hold down the throttle to pump plenty of air through, just like in the days of carburettors ?

 

Anyway, lesson (re) learnt and no more very short journeys !

Have your spark plugs been looked at or replaced in recent times?

Has the Air Filter been looked at and replaced in recent times? 

 

The filling stations have winter spec petrol on sale now and it is less hygroscopic. 

Is you car running petrol from recent fill up,s and is that E10 Unleaded in the tank?

1 hour ago, Austin 7 said:

I can only assume that this is due to the spark plug insulators absorbing fuel vapour overnight, or maybe the catalyst getting loaded with unburnt fuel or condensation from the previous cold starts and thereby choking the exhaust.  Maybe the ECU has a "clear flood" mode if you hold down the throttle to pump plenty of air through, just like in the days of carburettors ?

 

That made me laugh out loud 😀

 

No way is even a smidgin of unburnt fuel allowed to pass through to the exhaust on a modern ECU equipped engine with Lambda controlled mixture, faulty spark plugs aside and I second the advice to check them, but you would notice the misfire, its been 30 years now since anyone was able to flood a petrol engine.

 

Spark plug insulators absorbing fuel vapour overnight! Where did you hear that one from?

 

Does your vehicle have the stop/start system? If so the battery will have been partially discharged before your two engine starts and 25m travel, if it was in good health it would not have struggled to start a 3rd time the next day, if you know anyone with an electronic battery tester then I recommend you have it checked to see what it estimates the remaining life to be.

To answer some of those points, the battery is only a few years old and is regularly charged by the car being used 3 or 4 times a week.  No stop-start (thank goodness).  Using fairly fresh E10, but last time this happened (years ago) was in E5 days.  Air filter is reasonably young, but airflow at cranking speed is pretty minimal anyway. I didn't "hear" about spark plug insulators absorbing fuel, that's just my own thoughts trying to reason out what's going on.  Lambda sensor is effectively out of circuit during warmup, and in my view during the crank/start phase the injectors will be pumping fuel but if it doesn't ignite for any reason there's only one place it can go - out of the exhaust valve and into the catalyst/exhaust. There was never any misfire in the normal sense, more a total non-fire.

 

Once I tried the full throttle technique the cranking seemed more vigorous and startup happened reasonably readily.

 

The plugs are due a change, and the new ones are sitting on the shelf nagging me so it will get done once it's not so flippin cold out there !

 

Anyone else have a view as to what's going on ?

While it's cold have a old Marmite jar filled with warm water the shape fits nicely in your hand so it keeps your dainty sticky mitts warm🤣 

Real men like Marmite🤣but if you don't, then I have a plentiful supply and could send you one!

I've learned a few things along the way ... one of them is if my battery shows any sign of letting me down it gets changed.  When a car won't start it transforms itself into a useless pile of metal taking up space on the driveway.  Batteries aren't all that expensive for your car and you can fit them yourself (as you well know, I'm sure).

 

I take my car to a trusted local independent for servicing and repairs. he does what needs to be done, when it needs doing ... irrespective of the weather.

 

Thge car has never let me down.

 

Regarding cold starts and only driving a few yards ..... it's a relatively modern, generally reliable, inanimate object without feelings or emotions. It's there to serve you, not to be fussed over, and if it won't start then there's something wrong with it ...  you ought to be able to start it, move a short distance, turn it off and expect it to start next time. Take it to be serviced / fixed and rerturned to you in good order, and change the battery if it needs it ... the start of winter invariably shows up a weak battery.

The OP has not posted age of his Yeti, but my MY16 Octavia flags up the message 'do not depress throttle when attempting to start engine' if I so much as touch the pedal during start - the ECU calculates required volume of fuel for engine start. 

Let's be clear about this.  The car is 11 years old with 70,000 miles. I use it 3 or 4 times a week and it always starts immediately, hot or cold, rain or shine.  Then I do two cold starts in quick succession and drive a total of 50 yards, stopping the engine well before it has warmed up.  Next day it will turn over but not a sign of starting.  Hold the throttle fully down for another attempt and it starts.  Since then it starts immediately every time.

 

I am convinced this is a flooding issue, i.e. Air /Fuel ratio below the threshold for ignitability (about 8:1) and I suspect any AA or RAC man would tell you they have encountered it many times.

 

So my post was just to help anyone else to avoid the same mistake, or to know how to simply solve it without calling for breakdown assistance.  I don't need a new battery !

Edited 29 November, 20232 yr by Austin 7

14 minutes ago, Austin 7 said:

I am convinced this is a flooding issue

Me too. 

Thanks for posting. 

 

Austin 7, I am like you in that I try to avoid starting an engine for only a few seconds of running. I don't like the idea of the acidic condensates sitting in the engine and exhaust from short engine runs. 

 

Glad you got it sorted.

 

Incidentally, I note you used the term "Clear Flood Mode". By chance, I first heard about this yesterday watching Youtube where a guy suggested using it to pre-fill new oil filters ( that were side mounted or angled downward so they couldn't be pre-filled by simple pouring before fitting ). I have no idea how common this feature is on new cars, especially Skodas, but this high-tech. stuff starts to grow on you, in my case, after years of being a Luddite 🙂.

Clear flood mode is an urban legend, a hang up from over 30 years ago when all but a handfull of vehicles had already transitioned to ECU controlled fuel injection.

 

On a carburettor opening the throttle butterfly wide open will create a zero depression across the idle jet and no fuel will be drawn, it was a very valuable gesture to clear a flooded engine which could be a frequent occurrence with manual and primitive automatic choke controls.

 

All modern petrol engined vehicles have fly by wire accelerator controls, if you put your foot to the floor when starting it wont make the slightest difference to the stepper motor controlled throttle valve, it will remain closed or partially open as the ECU instructs it for the optimum starting configuration according to engine temperature and a host of other input variables.

 

If there is not combustion in a cylinder it will be down to a weak spark, faulty injector or no fuelling, ragged starting and uneven initial idle are all indications of a spark plug problem on one cylinder, four would not fail at once, with a good spark it is pretty much impossible for a fuel injected ECU controlled engine to flood and in any case the fuelling would be inhibited very quickly to protect the catastrophic convertor.

 

The engine will not have started due to no spark (immobiliser etc) or no fuelling putting the throttle to the floor will have had no influence as to why it did eventually start, you should not discount well intentioned advice about having the battery checked, you will find multiple examples on this forum of starting and random other electronic problems being resolved by a battery change, I'm not suggesting that you replace it but have it tested and also have a VCDS scan for fault codes.

 

A faulty engine temperature sensor could create an over-rich starting mixture (but only within strictly defined paramaters, not a flooding condition) and coupled with worn spark plugs may cause some restarting difficulties on a hot or partially warmed up engine, this could be checked using live data on VCDS.

 

On 28/11/2023 at 22:52, Austin 7 said:

The plugs are due a change, and the new ones are sitting on the shelf nagging me so it will get done once it's not so flippin cold out there !

 

I think you have probably answered your own question.

6 minutes ago, J.R. said:

Clear flood mode is an urban legend, a hang up from over 30 years ago when all but a handfull of vehicles had already transitioned to ECU controlled fuel injection.

 

 

I am having second thoughts about this, I can see the utility of being able to crank the engine without it starting after an oil filter change, someone mentioned the manual saying do not put the throttle to the floor when starting the engine.

 

I will try it on mine but its a diesel engine, could anyone with a TSi try starting their vehicle with the throttle pedal fully depressed and report back what the result was please?

No point comparing the 1.4 TSI with a TDI, and my experience is 1.4 TSI Twinchargers and no point me comparing that with a 1.4 TSI. 

 

Flooring the throttle is not Simply Clever to try starting in my experience with a twincharger.

Then as to oil filters on the top of engines, VW changed the filters in 2012, but is when you see the difference of the Black or Silver ones.

I tried it on my diesel, it just started with exactly the usual parameters despite the throttle to the floor then after a momentary but perceptable pause when the revs dropped to the usual running idle speed the engine then revved up to the stationary 3Krpm rev limit in response to the throttle pedal position.