Change the coolant sensor, cheap and fairly easy (may damage the old one getting it off with a socket...). No need to drain coolant I think, just a small leak.

Replace the damaged exhaust section, should be cheap and easy on your Punto. Avoids the lambda getting a lean (high O2) reading and telling the ECU to add more fuel.

Get the ECU fault diagnosed, it will probably give a temp or lambda sensor fault.

i changed ht leads, coil packs, temp sensor, spark plugs, disconnected lambda and its same, rly hard to start and rough idle + some sort of metal clunk in engine when applying more gas while driving and it has almost no power

as said only error shown in mes was lambda

need to buy compression tester to check if its head gasket

metallic clunk under load worries me most from what you have said... does it turn over nice and easily and smoothly if you turn the engine by hand from the crank (it will be hard to do without removing spark plugs first).

yea engine turns smoothly by hand
and its not that hard to turn even with plugs still inside and car in neutral

is there something else i could try before i take head off, apart from compression test

You should fix the exhaust (if you haven't already) and tick off the diagnostic faults (+ causes). You should do a compression test since this should indicate any faults with the timing, valve clearances etc. If there is some mechanical noise then this is a worry - could something have been damaged by the garage? If they set the cambelt wrong initially then there could have been a valve collision but I think the 1.2 8v is non-interference?

An auto-electrician can diagnose a faulty lambda sensor by putting a scope or meter on the wiring loom, or by reading the ECU.

yeah all 8v FIREs are non-interference... all the 16v and tjets are interference.

So metallic rattles from bottom end is most likely gonna be big end bearings i reckon.

blu73 said:

yeah all 8v FIREs are non-interference... all the 16v and tjets are interference.

So metallic rattles from bottom end is most likely gonna be big end bearings i reckon.

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what caused that? did i start engine with wrong timing to many times?

impoossible to say, and not even 100% whats happened... But in most circumstances where the engine hasn't been totally hammered (which i assume this hasn't) - bug end failure would normally be due to dirt in the oil system somehow which causes damage to or oil starvation to the bearing. So really old oil could do it for example.. Or if its been apart then improper assembly could be the fault.

But it could be something else and really metallic clunking/rattling is never a good thing and pretty much impossible to diagnose without actually getting inside to check stuff - i suppose it could even be something broken off and bouncing around in the sump which of course also isn't good but i couldn't say anything for certain other than i would be worried about such noises and it warrants either investigation or just replacing with known good bottom end if you have access to one.

is this somehow related to first spark plug not screwing in fully, cross thread, it is like this for years

i changed oil +filter on 4.2.2014 selenia 20k
and was just topping up since cuz of massive oil leak, that turned out to be sump leaking, so i changed it and topped to max on 14.4.2015, oil filter changed on 11.4.2015

i wouldn't worry too much about how its happened really... these things happen, important thing is to get to the bottom of what is making said noise and either fix or replace it.

this happened 2 months after i changed sump, must have done something wrong probably

maybe disturbed the oil pickup somehow, or just got some foreign object in there... like i say though, get it opened up and have a look and try find what the problem is. That should give you some idea how it happened in itself.