Papez

This was introduced on later models of Estelle, thermostatic flap that automatically kept intake air temp around 30° - in Felicia, there's flap inside of the airbox that closes once engine heats up, I'm not sure what exact temperature is, but I guess there's some hysteresis, as the flap stays closed for quite some time after the engine is turned off. Part that has fallen is just adapter that should be connected to warm air intake hose. Cold air hose is hidden beneath the airbox and goes through front wall.

It's warm air intake, which should be connected to hose going to exhause heat shield. It seems that the hose got shredded by belt..

In 1.9, thermostat is in coolant pump housing.

Switch in the starter makes contact even when pinion is not fully extended, so it's possible that starter spins for a moment without load (that happens quite often when engine starts sucesfully, it's just barely noticeable over engine noise), especially if there's unreliable contact to solenoid.

From what I've read, this is true - GL5 was developed for hypoid gears, typically used in differential. It typically had higher contents of sulphur/phosphor additives, which cause corrosion of bronze syncro rings. However, there are cars that have transaxles with hypoid gears (typically 4WD, like Audi) so oils with GL5 specification that could be used in gearbox were desirable, so they probably developed new additives to get oils that are capable to work in both GL4 and GL5 specs.

Starter motor sounds fine, but if you have issues with starting on key, it could be bad ignition switch - it directly engages starter's solenoid, which causes contact wear over time. The sensor in photo is knock sensor - it's there to detect "sound" of detonation, so ECU can change timing if detonation occurs.

Fabia is VW based, so its shocks are different. Favorit has similar shocks, but they have too soft rating for the pickup, plus Felicia pickup have different rear shocks, without spring plate. Try searching with OEM codes: 6U7413031 A/B front 6U7413031 C/D front for models with ABS 6U7513031 A/B rear. Unfortunately, I don't know what's the exact difference between variants.

1.9D should have 3 speed fan and different resistor - 6U0959263A - are you sure you have 4 speed one?

1.9D has two speed fan, with 95 and 102 degree switching points. First speed goes through resistor, it's possible that it has burnt. Or it can be fuse or other electrical issue. You can test the fan by disconnecting plug from switch in radiator and shorting contacts in the plug by piece of wire for short time - according to schematics, 3rd pin is +12V input, 2nd pin is 1st stage and 1st pin is 2nd stage.

Iirc, original supplier was NGK, and Bosch units were reported as less reliable. If the sensor won't fail entirely, it won't generate an error code, it requires skilled technician and maybe even exhaust gas probe to check proper function. By tapping I meant that idle almost doesn't increase - it seems that deactivation of idle switch in throttle body is enough.

What brand of lambda did you use? Also, did you change gasket between exhaust manifold and head? This function of higher idle RPM seems to be based on temperature - it generally took longer to settle in winter, than in summer. So I'd try temp sensors readings, thermostat valve function and lambda heater. Plus, one interesting thing, I could often "kick down" rpm by tapping gas pedal, often shortly after starting. How do you perform an ECU reset?

This is an MPI engine. There's no fuel going to throttle body. You can se injector rail on intake. What's the weather like when this happens? I had issues caused by condensation inside of ignition module, when it's isolation cracked. However, this sounds more like there's issue with starter motor or battery/wiring. However, it's all wild guess without diagnostics...

So you need to help starter by pushing it down the hill? There's no carburettor, that thing on the top is just a throttle valve.

I was talking about some more modern, like VW's TSI Engines that also "dump" fuel to exhaust to not overheat turbo and converter at high loads In felly, there's some hysteresis - you need around 2000RPM to initiate cutoff, but then it can go to 1500ish before it starts again. Not sure why it's programmed that way.

Could you please further explain this part? What do you mean by "it has both"?

Not sure about modern bikes with oil injection, but older two strokes with oil-petrol mix couldn't use engine brake, as carburettor couldn't provide enough oil. Two stroke cars even had one way bearing to disconnect the engine. In carburettor engines this did save fuel, as they usually didn't have any way to cut off fuel when engine was driven beyond idle rpm with no gas (although I've seen some DIYs for Estelle to implement that system) Older ECUs didn't mind, newer usually know which gear is selected, plus I've read somewhere, that some modern engines keep injecting some fuel to keep catalytic converter warm.

This issue is probably caused by thermostat valve, that's quite common issue. Temperature sensor has two outputs, one for dashboard and one for ECU. Without diagnostics, you don't have way to check its readings. I suspect the cause is crank sensor, if it was swapped with replica instead of genuine part, it could fail again. It is one of crucial parts to get engine running, others being ignition module and fuel pump. It could also immobiliser issue, but in that case, it would start for a second and then cut off.

This was ONLY way to start our Estelle in winter. Oil in gearbox became so thick, that it stalled the engine if clutch was released too quickly.

Like @Thefeliciahacker says. Just short time necessary to let engine stabilise and go, with very light driving until it warms up. in winter, I started the engine before cleaning windows, so I had at least some heating available once I sat in the car.

Most efficient way is to carry as much momentum from road before. Even speeding up, if you go downhill before, keeping it at highest gear possible. Unfortunately, I know nothing about how carburettors are set up.. I guess it's better to keep them at 1st stage and keep from rapid changes of loads, but I'm not sure about that.

ULEZ is Euro 4 for petrol, right? But it depends on variant, there are 6 variants (I think), only two being Euro 4 .

There is one engine that is relatively easy fit - Fabia 1.4 MPi - Euro 4 compliant, very similar to 1.3MPI, similar injection system, although it's need modifications. Also, engines used in VW Lupo should be relatively easy mechanically. But wiring will be different story.

Wouldn't this mean that actual range should be better than listed? As 42l is a nominal capacity of Felicia tank. It applies to Favorit, too. They used plastic tank, because it allowed better use of volume under rear seats - it was shaped to fill all available space. Steel tank would allow only around 30l of capacity.

600km range on 42l fuel tank amounts to 7l/100km - that's nothing unreal, I had average consumption on tank between 5,8-6,2, depending on driving style... With 5,3 record on a 150km trip (with a fully loaded Estate). I never got beyond 7l

Try to accelerate with gas pedal in about 3/4 - it might sound wrong, but gasoline engines have highest efficiency with open throttle valve - so most efficient way to drive is heavy foot and get to highest gear as fast as possible. Using engine brake on downhills and coasting on straights also helps a lot. 60-70km/h is fast enough for 5th gear, if you don't need to accelerate. At those speeds, immediate consumption should be below 4l/100.