So, potentially into phase 2 of the Felicia Combi project!

Currently we're mulling over starting the following;

Replace the temp sensor

Throttle body clean (although I don't have the equipment to reset the ECU)

Removing all breather hoses and checking for blockage

Next though, we're considering valve stem seal replacements - has anyone done this? How easy/difficult is it to do?

Any other thoughts on how to minimise smoky exhausts?

Is the exhaust smoke blue?

Is the engine using oil - if so, how much per 1000 km?

Has a compression test been done?

I don't believe it is blue or white, I just think it is excessive - if I had to put a percentage of 'how' excessive, I would say 25%. We haven't really driven it much TBH, my son is taking his driving lessons, and I don't use it much, so I can't say how much oil it uses. And no, a compression test hasn't been done - we don't haven the equipment to do that, but it is something that we may get a better equipped friend to do in the next couple of weeks.

As Warrior193 has put plus as follows.

IIRC there is/was a recent thread(s?)/posts about throttle body resets (I forget the exact details) in this forum, no need for scan tool IIRC. I'm a big fan of properly cleaning a throttle body (off the engine).

Loads of posts on temperature sensor.

Look up how to check crankcase breathing, there's an easy way, saves taking all the hoses off but if you do you could clean them inside and out of you want.

Valve stems might be covered in the forum or in the Guides section.

What you see from exhaust might just be lack of use and/or a minor fueling issue. When you've done the full servicing, cleaned the throttle body, checked the breather hoses then, if available to you try filling the tank with a petrol that has a highr cleaning additive package (higher octane ones in the UK) then once you are into that fuel, or add a fuel system cleaner get the engine fully (oil) warmed and give the car a sustained "Itailian tune-up" (more about high revs than high speed) that might help to blow some **** out.

Engines (and cars) are designed to be used not sitting getting damp and stiff.

Thanks both, good points and will follow your guidance! :-)

First I would do a compression test to rule out piston wear etc. If it comes back fairly equal and above spec then as said PCV etc and finally valve stem seals. Not sure if they can be done with head in place. On a very old Fiat my local garage fed soft string into chamber and compressed it to hold valve to replace broken spring so may be possible to do stem seals the same way. Check as well that the coolant isnt dropping and theres no oil in coolant. If its a diesel then it may be poor pattern/worn injectors that's causing smoke.

Alasdair

On 01/05/2026 at 11:20, TonyW1967 said:

(although I don't have the equipment to reset the ECU)

You can reset the ECU very easy by yourself BUT if there is an error code for a real problem this will show-up again.

You have to make an ECU-test to see if there is a specific code that will guide you, changing random parts won't help to solve the problem, it's a ''guess'' job.

2 hours ago, D.FYLAKTOS said:

You can reset the ECU very easy by yourself BUT if there is an error code for a real problem this will show-up again.

You have to make an ECU-test to see if there is a specific code that will guide you, changing random parts won't help to solve the problem, it's a ''guess'' job.

And to check error codes, I would need the VAG OBD system?

Yes, it's the only way to read them no matter if it's amateurish like OBD 11 or Professional like a VAG-COM scan tool in a repair shop.

You also need an emissions check from a repair shop,will help you pass the MoT test.

To be honest, the smoke isn't that bad, it's not blue or white, IMHO it's probably nothing to worry about - it's driven very infrequently which doesn't help, but that will change soon, so we'll take it to a local garage for summer tyre fitment, and get them to check it while it's there.

The Lambda sensor is the original with so many Km's on it?

20 hours ago, TonyW1967 said:

And to check error codes, I would need the VAG OBD system?

There are threads and posts here about how useful (or not) scan tools can be on these cars but even with the latest cars and best scan tools for them they are just another diagnosis tool, not as some believe the absolute ultimate to give exact answer. Sometimes they do pinpiont the cause of an issue but even then this should be checked and cross referenced with other diagnoist tools (multimeter, human senses, common sdense, ect.) and often the scan tool just pionts out what/where the error code is reported from and many just shoot the messager without thinking or checking or cross referencing further.

A car of this age will tend to give more generic error codes that might, or might not, help and only tell you what you already know.

Any scan tool that has the programing for the model and year would pull up error codes and the OBD 2 codes mandated at the time.

Of course if it's AI generated it'll be 110% correct everytime. 😆

IIRC there's a period video(s?) on YouTube with the diagnostics (machine) training on the Felicia that might help with the level of the systems at the time, IIRC(?) I posted it in a thread on here (or perhaps I just watched it?).

Edited 4 May4 May by nta16
typos

32 minutes ago, D.FYLAKTOS said:

The Lambda sensor is the original with so many Km's on it?

1 hour ago, D.FYLAKTOS said:

1 hour ago, D.FYLAKTOS said:

The Lambda sensor is the original with so many Km's on it?

I wouldn't know, the car has 146,000 kms, and we don't know the service history prior to last year.

IF it's the stock (NGK) a replace with a new (NGK only) would do only good.

I would see if the local garage could scan it if possible and it might ping something up. If its sitting for long periods then as its an older car I would expect some smoke due perhaps to condensation or oil leaking down into pistons while sitting. All my cars are fairly old and create a bit of smoke if I haven't run them for a while which clears once driven a few miles plus unleaded petrol if it is a petrol car will absorb moisture over time due to the ethanol being hygroscopic. I wouldn't bother replacing anything until the local garage has scanned it. There are too many folks out there that spend money on a fault without knowing exactly where the fault is. From memory to reset ECU on older cars you can disconnect battery touch terminals together and leave for an hour or so,reconnect battery and it should reboot the system. Wether it would clear codes I am not sure.

3 hours ago, D.FYLAKTOS said:

IF it's the stock (NGK) a replace with a new (NGK only) would do only good.

I don't mind doing that, but the car starts first time, every time, so does it need replacing?

Depends on how it runs and you won't really know that without a few starts and reasonable length drives under various conditions, you were concerned with reducing possibly smokey exhaust output.

As Alasdair has put car not driven, ethanol fuel settling out and sucking in moisture, moisture and oil drain in engine, are never best conditions for exhaust output alone, never mind engine. You need to get the engine up to full oil warmed temperature then if the car is running OK have the pistons and rings going at around peak torque for a reasonable time, get oil around and to clean cylinders and to have larger volumes of filtered clean air going through the engine and out of the exhaust, clearing the probe(s) a bit whilst doing so. Petrol with additional cleaner additive package will also help clean the fuel system and engine and with exhaust. The more fuel and air you can put in the more of everything that goes out the exhaust. The engine is just an air pump on four wheels.

Edited 5 May5 May by nta16
typos

Thanks, I guess we just need to run it more often - I did add cleaner additive a few months back (to a full tank), so we'll get it on the open road.

23 hours ago, TonyW1967 said:

but the car starts first time, every time, so does it need replacing?

Lambda sensor it's not for morning start only.

https://www.briskoda.net/forums/topic/503246-confusion-with-bosch-lambda-sensors/

https://www.briskoda.net/forums/topic/503246-confusion-with-bosch-lambda-sensors/page/2/#findComment-5652665

Back then the car started-accelerated ''as it should be'' but due to that lambda sensor (which was ''OK'' by the parts catalogue) the fuel consumption was

14,7 ltr/100 Km or 19.21 UK Mpg which was far the worst number i had ever seen.