Agree with Wee Smurf.

Learning of the potential problem from this forum, I took the offending screw right out, and replaced it with double-sided tape. Seals the hole, firmly fixes the plastic moulding, and can be eased off if ever the need arises.

Sweetsixteen.

The major problem is due to distortion of the air cleaner box, particularly at the back where the three male tongues engage with the three female slots and also stripped threads at the front which mean the front lip doesn't crimp down properly on the gasket......and that is where there is direct down flow of air from filter into turbo and intercooler. You need to remove the air cleaner box and reshape the housing and cover so that they are true and as moulded. What happens is that because one can't see if the tongues are ALL properly engaged when changing a filter the back wall of the housing gets pushed back around the middle tongue and the back lip of the cover gets pushed towards the front of the car . The engine heats up and the bonnet too in hot weather and the plastics get cooked into their new distorted shape! The answer is to remove the whole assembly and heat up the plastic moulding locally and reshape them to their original shape ......easily done with a heat gun, blow lamp , or gas ring . Just keep the heat source well away from the plastic so heating occurs over a wide area. You can bend it back into shape wearing oven gloves. The next important thing is to make really sure the three front screws are crimping the front of the gasket properly as the turbo when it's spinning fast will be creating big negative pressure downstream of the air filter......right where a leaky front gasket lip will allow water to be sucked directly into the turbo feed. If any are stripped a slightly over sized BUT SHORTER wood screw will make sure the front air filter cover lip is crimped properly.

Whether or not water is coming in via the the feed hose from the front scuttle is hard to pin down but it's interesting to figure out how much air is going in there! A 1.3 litre engine with a bit of boost will suck in maybe 1.5litres of air per revolution. With an engine that's spinning at 2500 rpm thats 3,750 litres per minute.....or 3.5 cubic metres per minute! Thats a bunch of air in a very small cross section of hose which must be moving at quite some speed and any water droplets on the walls of the hose will be pushed along the walls like water at speed on a windscreen . Gravity won't have much effect probably. Another factor which MAY play a part is the sighting of the intercooler which , because it's so low acts like a P trap on a sink . Any water which comes into the inlet tract will fall down into the intercooler which also may fill with condensate which has condensed within the intercooler. It's just possible that water will collect there until the intercooler fills with water ( particularly if the motor is driven gingerly). When someone gives it some welly the engine could then suck from a large reservoir of water in the intercooler and drown itself! I reckon a screw down drain plug on the intercooler would be a good idea.

......also VERY important when replacing air filter to remove whole housing from car so you can eyeball the three tongues on the air filter cover and make sure they are ALL properly engaged . That is the ONLY way you can be absolutely sure you've got an air and WATER tight seal right round the the air filter gasket lip. Also .....never jet wash these engines! If you do reshape the air filter mouldings using heat and manage to reshape the thing to what it should be .......further engine heat in use will cook it into its new reshaped......shape!

Lot of work there to rectify what is a very poor and badly made design. I reshaped mine last year, but after giving it some further thought I realised that I'd just kept the basic problem. The standard air box is junk. Better still, as I've posted before, scrap the airbox completely.

Follow the air inlet path from the grill trunking, through the airbox to the Maf and you'll get lost in the maze! It's a wonder that the poor old air can negotiate all the twists and turns!

I fitted a cone filter directly onto the Maf. Simple and effective, and all problems gone.

Goes better and sounds better too.

Charge density .....or air temperature .....is important. Putting the inlet right behind the rad where air is warmer will reduce the amount of available oxygen because the gas is warmer. Also the air mass in front of scuttle ( particularly at speed) is at high pressure and is cooler . Fiat have sourced the combustion air from there for a good reason.....more power and more torque. When I bought my car the fat rubber hose from scuttle to air filter housing was missing. In hot weather I felt power was down .....probably due to the warm combustion air being sourced from behind radiator. I sourced a second hand hose to make sure charge air was under pressure and at low temperature ......and sure enough power and torque are improved.

I'm going to eyeball my front scuttle/grille this morning to see if there's some way of placing a baffle and/or creating a plenum chamber there to stop any airborne water droplets getting into inlet duct. My hunch is that any water ingress problem via the front scuttle will only exist in very wet weather at high speed and with big throttle openings/turbo boost.

Prontissimo said:

Putting the inlet right behind the rad where air is warmer will reduce the amount of available oxygen because the gas is warmer.

Click to expand...

If anyone is after greater economy instead of greater power, having warmed air enter the inlet tract by drawing air from around the engine area is a bonus.

Depends what you're after really. As it happens, I have also shrouded my cone filter and ducted cold air to it using the original inlet on the front grill. My choice.

You pays your money ... and this is a very old thread!

All that air intake temp is a little misleading.

A turbo engine is not totally reliant on air temps entering the intake, but is on air entering combustion.

Sure as most school kids know, cold air is denser in oxygen and oxygen facilitates combustion.

Trouble is now with the turbo in between the two compressing the air.

Compressed air is exceedingly hot (stick your finger over the end of a bicycle pump), therefore it's less dense in oxygen.

Cool, cold, warm or even hot air is now unbeliveabily red hot post turbo!

Intercooling helps cool the charged air and increase density, but the PCM needs to know the volume of air entering plus the pressure to work out correct fueling.

From the volume entering (MAF pre turbo) and the pressure (MAP post intercooling) it can work out the available oxygen entering combustion.

Intercooling only really works when air passes through it (when the car is moving) and can if incorrectly sized act as a heat sink, so drawing cold air when idling and the turbo isn't fully working will see the dense air being more effective than it would with warmer air.

The difference between under bonnet air temp and post turbo air temp is massive on the move, even after intercooling, so much so it's not the temp of the drawn in air that really matters, but the effectiveness of the intercooling.

Goudrons said:

All that air intake temp is a little misleading.

A turbo engine is not totally reliant on air temps entering the intake, but is on air entering combustion.

Sure as most school kids know, cold air is denser in oxygen and oxygen facilitates combustion.

Trouble is now with the turbo in between the two compressing the air.

Compressed air is exceedingly hot (stick your finger over the end of a bicycle pump), therefore it's less dense in oxygen.

Cool, cold, warm or even hot air is now unbeliveabily red hot post turbo!

Intercooling helps cool the charged air and increase density, but the PCM needs to know the volume of air entering plus the pressure to work out correct fueling.

From the volume entering (MAF pre turbo) and the pressure (MAP post intercooling) it can work out the available oxygen entering combustion.

Intercooling only really works when air passes through it (when the car is moving) and can if incorrectly sized act as a heat sink, so drawing cold air when idling and the turbo isn't fully working will see the dense air being more effective than it would with warmer air.

The difference between under bonnet air temp and post turbo air temp is massive on the move, even after intercooling, so much so it's not the temp of the drawn in air that really matters, but the effectiveness of the intercooling.

Click to expand...

So what's the 'offside' rule again?

I think the fiat engineers probably did some heavy duty design modelling on the intake system to tune it right for the installation. My comments about cooler scuttle intake air were that any reduction in temp makes less work for the intercooler and is likely to mean a denser charge in combustion chambers......so more oomph. A clean intercooler helps....get the Hoover out and get they bugs off the front of it!

There's no doubt they did.
Remotely locating the intake and shaping the air flow through resonators will reduce acoustic disturbances so the increased induction roar the turbo creates does not intrude in the cabin.

Post turbo charged air temps even after intercooling will be more than double ambient air temp which is something compression ignition engines utilise, the hot air aids ignition of the fuel.

Air density on turbo equiped vehicles is regulated by the efficency of intercooling so it's true a clean intercooler will benefit engine performance, particularly removing and limiting the build up of crankcase blowby from within.
A tiny amount of oil can reduce it's efficency drastically.
It also mixes with soot via the EGR system and restricts manifolds, intake ports and pipework.

Thanks for your expert info.

Check this thread on water ingress to air cleaner etc....."Bad 1.3 multijet air filter housing water ingress" . Mods to air aperture/gasketing under grille.

Direct link to thread.......https://www.fiatforum.com/panda-guides/426032-bad-1-3-multijet-air-filter-housing-water-ingress.html