UK-POLOS.NET - THE VW Polo Forum

Ah, good to clear that up, I will leave my posting as is as it would make that last posting by bvs seem slightly weird, also I think that some air cleaners did have these screws and maybe they need removing if the plan is to replace the capsule.

Edit:- I had forgotten about the fact that wino's "other" car was a 1.2, so again good to clarify.

Yes absolutely RUM - if I had wanted to replace the capsule then I would have had to remove the torx screws thus gaining access to the capsule housing/bracket.
But because I just did the 'free' woodscrew modification then I only had to remove the air filter to gain access (I was changing the air filter anyway as MOT next month )

All went OK today - the overnight forecast was +6c but as usual it was colder than forecast (the local weather station where they get the readings from is Strathallan Airfield - 6 miles away) and we set off for the Gliding Club at 0730 with the ambient temperature 0 deg c.On the 35 mile drive the ambient was varying from -1.0c to +4.0c - the engine never missed a beat - the Humidity was approx 90%.

So - OK so far.

Another 70 mile return trip yesterday,the polo seems to have a little more 'grunt' at lowish RPM and the engine seems a little smoother in its power delivery - so we are happy with Cold Intake Air at the moment

Polo still seems to be happy with permanent cold intake air in varying weather conditions,seems to have almost got rid of the last vestige of 'hesitation'/flat spot when moving the accelerator pedal from 'off' to 'on' during gear changing and whilst accelerating away from a 'slow down'/coasting.
We now have (at the moment) a very pleasant little car to drive ,when first aquired she was really sluggish and down on power,but I have gradually worked through small improvements/maintenance to the engine in the last 4 years - hope the upcoming MOT is ok LOL

So with my flap valve missing from the airbox (1.4 BBY) is the engine receiving warm or cold air?

littlepolo wrote: ↑Wed Mar 06, 2019 2:52 pm So with my flap valve missing from the airbox (1.4 BBY) is the engine receiving warm or cold air?

If you have removed the plastic flap that diverts the incoming air either from the front or the warm air tube, then the incoming air will be a blend of both, probably 90% cold air directly from the front of the car due to the ram effect and that that path is the path of least resistance to incoming air.

Yes I agree with RUM - it will be a mix of Hot/Cold air but I would not like to guess the mix ratio

Should be easy enough to fit a flap/blanking plate to block off the hot air path.

Wino on the skoda forum reckoned he got improved fuel consumption with cold air,we have not done enough mileage yet to comment.

Tried out my new 'Torque' app/OBD dongle thingy today and we went for a short (14 mile) drive to get some real time engine parameters - Engine Intake Temp started off at +9 deg c (agreeing with ambient) but was up to + 35 deg c at the halfway point - by the time we got back into town it was reading +42 deg c - so even with the Intake Flap closed - the engine is still getting hot air LOL.

Decided to refit the warm air flap after tidying the shed and finding it. Unfortunately it disintegrated in my hands. Is it possible to get the parts (the flap, actuator rod, etc. individually)?

No, I don't think so, put it this way, it does not get offered as a spare part for that assembly.

Thanks. I thought as much. The hot air duct is currently blocked with an old pill box. Will see how she goes.

Thought I'd check on the possibility to obtain the flap valve parts and can confirm they are not available separately. You need to buy the whole engine cover/airbox assembly. Price is around £220. I'll check the breakers yards. I've been driving without this for a few years now and just wondering what difference it will make if refitted?

I managed to get hold of a used airbox off a 2005> model year Polo. The diverter was intact so I compared the two airboxes to find any differences. The later model has different ducting inside and is missing one breather union. Also, the screw-on casing for the diverter and the filter differs so I could not interchange those parts. I cannibalised the donor airbox and removed the diverter assembly (canister, rod, spring, and flap).

Before refitting I tested the canisters and found the old one is not moving at all. It looks like whatever was in it escaped as the pin easily fell out. The new canister's pin seemed to be protruding more and while it would extend (close the flap) it would not fully retract to allow more hot air for cold starting. Making the most of it I fitted the donor parts as shown below.

I'm guessing that there are quite a few older VAG vehicles driving around without the diverter working properly. The cost of a new airbox assembly is prohibitive. I wonder if it might be possible to obtain a suitable replacement canister separately.

Will monitor engine performance, hot starting problem, and fuel consumption to see if this half-way fix has made any difference.

I have some photos but encountered a message 'Sorry, the board attachment quota has been reached' If this is cleared I'll upload the images later.

Just a quick update on the outcome since fitting a working flap valve. Basically, the hot starting problem seems to have cleared. Strictly speaking I'm not sure the flap valve is working across 100% of the range of operation, but it's certainly diverting much less warm air to the intake when the engine is hot. Although we are in a cooler season the hot starting symptoms were present year round. So far so good. I cannot determine any effects on mpg at present due to the front o/s brakes binding slightly.

As for the pinking problem, this also seems to have all but cleared. Again we are in a cooler season but pinking was present year round depending on conditions (obviously much more pronounced in the warmer season). I had been using Tesco Momentum to improve the drive and this considerably reduced pinking. The last several tankfuls were plain supermarket fuel and since I've replaced the flap valve have not noticed any pinking. The real test will be in the warmer season.

For those with pinking problems, whilst a faulty oil separator could introduce problems with the mixture if you've not found any problems in that area it might be worth checking out operation of the engine cover flap valve.