Lumpy running after engine start on warm days

[briscaF1]

Hello

 

I've noticed that, after starting my 1.2 TSI (4 cyl) on warm days, the engine runs lumpily for a short while.

It feels like the engine is hesitating, like in the old days if mechanical points were worn out or plugs/leads needed replacing etc.

 

I've seen elsewhere on here that the engine may be running in a special mode for 30s after start (ironically for fast warm up) - does this apply to this engine and could it be responsible?

If this is responsible, since I imagine there is an ambient temperature sensor, why does the fast warm up cycle need to run on hot/warm days?

 

Cheers

 

[AGFalco]

Mine has always done that in hot weather.

Just be gentle with the throttle or let it idle for 30's and it goes.

I think it is NOT adding fuel unlike on cold starts.

 

Thanks, AG Falco

[steevs]

Mine does the same and I hate it.

 

Cold day, cold start, lumpy idle.

Hot day, hot start, lumpy idle.

Moderate day, hot start, sporadically lumpy idle.

 

I've replaced spark plugs, can't replace the fuel filter as it is in the lifter pump.

 

Not the air filter as I replaced that followed by a full MST setup - no difference other than slightly smoother pulling away/less jerky

 

I'm going to start investigating boost leaks followed by checking the valves for carbon build up as this is not normal.

Edited 2 July, 2021 by steevs

[rum4mo]

My wife's August 2015 Polo 1.2TSI 110PS is now at 34K miles and always starts smoothly and continues like that while it warms up, same if garaged or not - though it might slightly stutter at initial start up if not been started until later in the day on a hot day when the over night temperature was lower than usual, but nothing to prompt me into trying to sort it out.

 

Has anyone noticed a build up of oil mist ie wetness on the turbo output pipe where it attaches to the top of the TB?  I took that pipe off to replace the plugs and just re-used the original O-ring seals, then read on the workshop manual that these seals need replaced after that pipe has been taken off, I had noticed a build up of oil mist at the TB entry point only after having taken that pipe off. So, I ordered in  pair of new O-rings and fitted them, slightly oiling them to stop them getting scuffed while pushing the pipe back into place - but the same thing is happening, a know a small quantity of engine oil ends up being passed down this pipe, but that is expected.

[steevs]

4 minutes ago, rum4mo said:

My wife's August 2015 Polo 1.2TSI 110PS is now at 34K miles and always starts smoothly and continues like that while it warms up, same if garaged or not - though it might slightly stutter at initial start up if not been started until later in the day on a hot day when the over night temperature was lower than usual, but nothing to prompt me into trying to sort it out.

 

Has anyone noticed a build up of oil mist ie wetness on the turbo output pipe where it attaches to the top of the TB?  I took that pipe off to replace the plugs and just re-used the original O-ring seals, then read on the workshop manual that these seals need replaced after that pipe has been taken off, I had noticed a build up of oil mist at the TB entry point only after having taken that pipe off. So, I ordered in  pair of new O-rings and fitted them, slightly oiling them to stop them getting scuffed while pushing the pipe back into place - but the same thing is happening, a know a small quantity of engine oil ends up being passed down this pipe, but that is expected.

 

I've got oil buildup in the same area, I think this is where the PCV feeds into, have had it since I got the car 3 years/ 20k miles ago.

[rum4mo]

7 hours ago, steevs said:

 

I've got oil buildup in the same area, I think this is where the PCV feeds into, have had it since I got the car 3 years/ 20k miles ago.

 

Oh yes that is where the oil is coming from for sure, but I'm a bit annoyed that it only started showing up on the outside of that plastic duct AFTER I had taken it off to make replacing the spark plugs easier.