RicardoM

The lesson that should be learned from this issue is that you never buy parts unless there is evidence based on a thorough diagnosis.

The differential is different than the input or output shafts.

@HardoPiiri Nothing wrong with the immobilizer. The error might have been there for a long time. Usually you clear the error and see if it shows back up after 2 engine starts. It is indeed a spark problem. Usually it is a corrosion problem. The connectors or the wires themselves. Have a very close look at the wiring between ECU and electronic ignition, connector included. Spray liberally WD40 in the connectors.

Obviously. Brake cylinders, brake lines, rear brake regulator (if any)

You will not be able to put the gears back without opening the gearbox housing. According to Haynes, opening the housing = rebuild. Find the nearest garbage bin and toss that book in.

@Larry97 The original schematic is below. Please disconnect the connector marked with a red arrow, take a photo of the pins of the sensor than post it here to tell you what to do next.

Very nice find. Keep it well. They will be always fashionable.

Do what the manual says. Disregard anything else.

Now you need to tell us what they are made of and how do they compare with the reliability of the factory ones. By the way, all rubber parts fail quick because they are made in China, regardless of the fancy package they are sold in.

Let's put everything about Skoda Felicia in a single, huge, never ending topic. That would make this section interesting for people searching for useful information. Like those shops "All for 1 dollar" where you enter and you can find anything you can think of.

@adamtyvm There is a dedicated section for Classic Skoda projects at https://www.briskoda.net/forums/forum/206-classic-skoda-projects/ Maybe you should ask a moderator to move your topic in the same category with the rest.

Very decent answer for a Felicia maintained properly. Anything else is paranoia for splitting hairs with zero efficiency and a waste of time and money.

@westie606 Define hot starting issue. No start at all? Hard start but eventually starts? Rough idle?

@areed Follow the advice I gave you 6 years ago. Use pink coolant of decent quality without getting paranoid about formulas. Use a Viktor Reinz head gasket. Enjoy. Be careful who do you take advice from on this forum.

What are your realistic expectations from using Speeduino in terms of power and torque?

@Adamskii You need to provide a lot more information about the history of the car before getting a meaningful answer.

@danilob Try fixing the problem one method at a time. For example, don't do timing chain and carbon deposits simultaneously. You would never know what was the culprit. IMO, getting rid of the carbon deposits will not make a difference. Maybe you will get a placebo effect because you will see a lot of white smoke out the exhaust and you will think 'that's fantastic'. Seafoam is another marketing BS. There are videos on YouTube showing before/after photos of the piston deposits using a mini camera. The effects are minimal. Carbon deposits are very tough to clean. Only mechanical brushing and heavy chemicals destroy them but you need to dismantle the engine lower part.

@danilob Congratulations for the comprehensive history. That is how you ask for help to somebody who doesn't have direct access to the car. I am not sure why you changed so many parts without success. Could it be improper diagnose? The normal process of repairing a car is this: diagnose -> find evidence of fault -> buy parts. Anyway, here is what I would do: - change the timing chain. NOW. For a neglected car, I am expecting to find a total mess behind the timing cover. Chewed sprockets, elongated chain, heavy marks on the timing cover, etc. It is quite hilarious reading that you check regularly the valves clearance when the timing chain is flopping inside all over the place. - put proper new spark plugs as indicated by the service manual.

Cold start issues are most often the result of the choke plate not moving / closing. But there are cases when the fuel from the float chamber slowly drains due to leaks in the accelerator pump gasket or the enrichment valve gasket.

Could you elaborate on the turbo conversion you want to perform? Try to be more specific. I don't want to spoil your project, but something doesn't sound right.

The last solution is the RED wrench. That means to apply heat to the side you want to expand then unscrew the bolt.

Who will make the interfacing between Speeduino and your car?

By known good battery I mean one from a car having the electrical system in working condition.

Check carbon brushes and integrity of the slip rings/armature.

Testing the alternator Test requirements !! ♦ V-belt or ribbed V-belt tension O.K. ♦ Battery O.K. ♦ Wiring at alternator and earth cable between engine, body and battery must be intact, tight and not be oxidized. Are you absolutely positive that ALL the requirements are met? Borrow a known good one from a neighbor/friend ?