DGPunto said:

While you had the air filter assembly off the top of the engine did you check the large and small tube that run from the filter to the top of the engine? They rot and at current age unless they're been replaced with updated versions they will have rotted through letting oil over the top of the engine and causing running problems

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Hi DGPunto,

thanks for your opinion. Today I had some spare time so I decided to have a look under the airbox.

So, as shown in the pics, I found a cut in the small hose that goes from I don't know where (??), into the airbox. It was fixed with some tape.
Which is the scope of this pipe and where I can buy it?
Then, I cleaned the throttle body and the MAP sensor. Also, I checked the purge valve solenoid with a multimeter getting the value of 19-20 Ohm. I'm not able to find anywhere if this range is it the correct one. Does anyone know it?

My question now is: could that broken hose cause a misfire only when the tank is full for more than a quarter?

Thanks to all! Hope to be close to the problem

That small pipe connects to the manifold I think and supposedly just pulls off. I traced mine down behind the engine and bought a piece of silicone pipe of the right diameter to replace it.

Don't think that will be your only issue but it will help

Another neglected car. Your throttle is disgusting. Clean it.
Small breather hose provides most of the idle air (rest comes from partially open throttle flap).
PCV System ("breather hoses") Guide: https://www.fiatforum.com/grande-pu...er-hose-replacement-1-2-1-4-8v.html?p=4351952

EVAP system solenoid can be clogged/stuck (open or close). Clean it too. Electrically it will be OK most of the time (so don't bother measuring with multimeter, just power it with 12 V source). It is also prone to leak vacuum (there are 2 o-rings, small and big, pay attention), when installed improperly (which is easy to do - weird retainer clip). Make sure it seats good (not crooked) in place.

List (incomplete) of possible problems:
- classic Grande issues, electrical, bad ground (earthing points Guide), bad battery and/or alternator (water drain bad design, pouring straight on the alternator), rotten fuse box,
- sparkplugs (check again if they are really new), leads, coils (may not be "OK" - not easy to diagnose),
- low fuel pressure and or injectors, plus EVAP solenoid valve issues,
- intake vacuum and/or exhaust system leak, malfunction (sensors and/or catalytic converter),
- bad timing,
- bad valve clearances (never been adjusted - very common in all 8V engines),
- some sensors, maybe (MAP, temperature, TDC, lambda, knock...),
- ECU failure (rarely),
- ...and so on.

Thanks for the help guys!

I will see if Im able to go through that useful list of problems.

I've got a question (another) could I clean the part in the pics with a carb cleaner?
Im referring to the part which goes into the big breather pipe

DonFrank said:

... could I clean the part in the pics with a carb cleaner?

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Hi Frank,

cleanliness never hurted anyone (AFAIK), specially when we are talking about tinny air flows/controls !
Regarding the cleaning agent, that depend on the material being cleaned, gotta be cautious here ! Obviously you shouldn't use aceton on plastics, acid on metals or clothing etc.
As an engine (and its parts) is morelikely oil & dust dirtyed, a mild temp water & soap solution, a paint brush and some elbow fluid would make miracles.
Chemicals can O.C. be used but might also completely ruin your part !!

BRs, Bernie

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