Long cold starts

[maTTew]

Hi,

I own o 2010 Polo 6R 1.4 16V CGGB, 117000km. Recently I started to experience that after night my morning cold starts are taking 2-3 seconds. Then it fires up and runs normally. Idle is stable, no power loss, no stalling. Next warm starts are OK.

I checked my coolant temperature sensor and its resistance is within spec, but I changed it anyway, was pretty rusty. I bought original part and changed even the o-ring and safety clip. No change for cold starts.

Then I cleaned my throttle body and run the adaptation with diagnostics. Car runs normally, but no change for cold starts.

What else could it be? No fault codes. Two months ago I changed all spark plugs (same type as before), oil and oil filter, air filter. I am using 98 octane gas from one gas station for years, real good one according to tests in magazine. I changed fuel filter two years ago. I can not smell or see any gas leakage in engine bay or anything suspicious at all.

[iichel]

Is your battery still in good shape?

[maTTew]

It turns the engine fine, it is old 4 years. I think it is ok.

EDIT:
I recorded video yesterday..
https://drive.google.com/file/d/18zmtIY ... sp=sharing

Maybe it is starting fine and I am just chasing ghosts, but I noticed it, so it is a new thing.

EDIT2:
I forgot to mention that I tried to prime fuel pump few times before start and it has no effect.

[RUM4MO]

It turns the engine fine, it is old 4 years. I think it is ok.

EDIT:
I recorded video yesterday..
https://drive.google.com/file/d/18zmtIY ... sp=sharing

Maybe it is starting fine and I am just chasing ghosts, but I noticed it, so it is a new thing.

EDIT2:
I forgot to mention that I tried to prime fuel pump few times before start and it has no effect.

That is very easy to do, ie get something into your head and start worrying, it does sound okay to me.

Edit:- one issue that these engines seem to or can suffer from in summer is "poor" starting due to a failure of the EVAC valve, not that I have ever had that problem but it has been mentioned a few times on the SEAT Ibiza forum with cars using that engine.

[maTTew]

It is around 19 degrees celsius here these days..

Where I can find EVAC valve? I can not find anything about it on Google.

[iichel]

I'd say this is a very acceptable engine start to be honest.

[RUM4MO]

The EVAP solenoid valve, if I remember correctly, is mounted in a large round voided rubber mounting, the pipe to it appears up through a hole on the RHS of the car. It is in the same place that it has been for many years for that version of engine ever since maybe 2002, so if you search for "EVAP" on a Polo, Ibiza or Fabia you should find a picture of it and where it is mounted in the car.

[maTTew]

OK, thank you, I searched EVAC and it is a EVAP

[maTTew]

Bad news everyone.

It is getting slightly worse day after day..
https://www.youtube.com/watch?v=tn06-mo7PP8

I am convinced now that there is a problem...somewhere. What about holding fuel pressure? Can I check it in VCDS or only with a gauge on a hose?

[maTTew]

Hi,

I changed the EVAP valve - it was cheap enough to just change it and not investigate, but it did not help. Any ideas?

[RUM4MO]

Sorry, no, not from me, when I listen to your short video clip again, I can hear that it is trying to start very quickly - and makes the car and camera shake, and then it starts properly.

If not fuel pressure, maybe fuel is leaking into a cylinder or 2 via a faulty injector.

So, if you have enough time before a cold start, try removing all the spark plugs and see/smell them to see if one or more is smelling strongly of petrol.

Similarly it might be that some of the injectors are dirty and so not passing fuel through enough for an enriched cold start demand, really just guesses - sorry.

Thinking back in time to when my older daughter had one of these engines in her late 2009 Ibiza, it might have always started "roughly", ie started shaking but taking slightly longer to start, which might mean my opening statement was not too correct, or was it.

Edit:- I had a similar problem with a 1986 Ford Orion Ghia 1600 Injection, they used the old mechanical Bosch K Jetronic fuel injection system which had just sort of valves with nozzles that would only "break" open under high fuel pressure. Ford were not interested in my claims that it was starting correctly and asked me to open the throttle while starting, which was the opposite to what the owners handbook read. So, I removed all the spark plugs and one or two plugs were still wet after an over night stop. I dried them and the car started as it should have done. So every day for a week I slightly unscrewed the high pressure fuel supply to the injection system as soon as I got back hone from work, then retightened it an hour later - the car started perfectly every morning. That car always started okay if stopped for only maybe 8 hours during the day. I solved that by buying a single new injector, and swopping the one that was in the cylinder that was causing the wettest plug to happen, then I cleaned all the injectors one by one and forced their pintle valve to seat better - made sure that I still had the "worst" injector out of the car, and that problem disappeared.

Of course your car has powered spray injectors, but they can also suffer from leakage etc.

[maTTew]

I finally had some time before driving to check my spark plugs. They are all dry, but they have more carbon on them than I would expected. They are brand new, changed this spring. Before I had the same type and brand (Bosch) for 4 years without problems.

https://drive.google.com/file/d/1nROGjV ... sp=sharing

I changed the fuel filter that has built-in fuel pressure regulator, no change. Even my dad thinks that the car does not starts normally. He borowed the car once and it started on second attempt - I assume he was not cranking long enough. After first start it starts normally.

I also tried to crank the engine for short period of time before actually starting it - not long enough to start up, just half second crank. After that, on second attempt, it starts right up.

[RUM4MO]

That plug does look quite sooty/black, though I suppose it can depend on how you use your car, ie if only short journeys they could end up like that.

As you are running out of ideas, try removing all 4 plugs an hour after you have used it - and check if any of the plugs are wet or smell strongly of petrol, make sure that you remember which plug came from which cylinder.

I've only ever fitted NGK plugs to all my VW Group cars that I have worked on - Bosch should be okay though, just me making a comment that is all.

After that examine all the vacuum lines.

[davidfun]

Could you solve this?

I am suffering with the same problem. The fuel consuption is higher than before, so I think this disorder related to one of the temperature sensor or O2 sensor.

[maTTew]

Hi,

I changed almost every sensor related except for lambda sensors and nothing helped. But I filled my car at different gas station then every time before and problems are gone.

But I did not have higher fuel consupmtion, just poor cold starts.