Technical 1.4 16v 95hp starjet - low on power and backfire on high rpm shifts

[AnteLo]

Hello, my friend has a 1.4 16v 95hp GP with VVT.

The car backfires on high rpm shifts, feels like it has 80hp and generally doesn't go well into high rpms.

it has fresh oil, very quiet lifters, maintained well and low miles

The flaps system has been disabled because it was faulty
The car has no check engine light
It's timed correctly and has been checked with the proper FIRE 1.4 VVT tools.

How does the VVT system work on these? Am I wrong to think it has been left in some kind of cat heating mode aka too intake cam too retarded?

Does anyone have any pictures of how the vvt system works, can the variator and solenoid be cleaned and such?

 

[GrandePunto PL]

1. It has fresh oil now. But what's the car history (proper regular maintenance or car abuse)?
2. Check the errors and parameters during a test drive, via OBD2: FES or "MES" Fiat specific software. Then decide what's next.
3. This simple VVT is like introduction into real hydraulics (industrial stuff, proportional valves and so on). The number one problem is oil cleanliness - yes you can remove the solenoid valve and clean it.

As far as I know the VVT here is probably "digital" (I mean it works or not). It is not really "variable" (it is activated fully during high load - "flooring" the car and that's it).

Actuator ("variator") can be cleaned too (there are videos on YouTube, people dismantle them - especially russians in models popular there: Albea, Linea, Doblo), but this is the last resort. Before that you should check the oil delivery, measure the pressure (at the oil sensor spot) and check the gasket under the camshaft cover (it's almost like "head" unfortunately, removing it means timing belt job), maybe there's a pressure loss somewhere.

 

[AnteLo]

It has quiet lifters which are a first indication of bad maintenance.

what parameters to check while drive, there is nothing useful.

yes I guessed it's an on and off switch like the older fiats

could you please guide me to the videos of solenoid and variator cleaning, I couldn't find them

 

[GrandePunto PL]

Where is "nothing useful"?
MES has parameters like VVT position actual and desired...that's a good start, diagnostics.

Solenoid valve cleaning (solvent is enough, you don't have to use ultrasonic cleaner), Polish forum: http://fiatpunto.com.pl/topic57963.html
As for actuators, do your homework! Use "cyryllic" alphabet/script, Yandex search engine or straight YouTube.
Example result:
There are multiple videos like that. Plus, all cars are similar in VVT design, you can watch almost any video (doesn't have to be Fiat specific).

If you can't search basic things in the Internet, how come you "timed the engine correctly"? I doubt that.

 

[AnteLo]

Interesting, I didn't know multiecuscan had

Thanks