Low Pressure in Cylinder 1: Skoda Octavia 2001 1.4 16V, Engine Uneven, Replaced Rings, Error 16490

Skoda Octavia 2001 1.4 16V
The engine runs unevenly, has no power, dims.
Vag shows error:
16490 - Manifold / Barometric Pressure Sensor (G71) / (F96): Implausible Signal
The pressure measurement showed:
cylinder 1 - 8.5
cylinder 2 - 14
cylinder 3 - 14
cylinder 4 - 14
after oil test:
cylinder 1 - 9.5
cylinder 2 - 15
cylinder 3 - 15
cylinder - 15
I changed the rings and after replacing it still the same:
cylinder 1 - 8.5
cylinder 2 - 16
cylinder 3 - 16
cylinder 4 - 16

Can anyone tell me what could be causing the low pressure in the first cylinder...?

Am I not mistaken that your pressure test rejected the rings as suspects? If the pressure has not increased significantly, then the valves are probably letting go?

I was told that if it rises, it's the ring's fault, so I gave up...
Does this apply to sealants or the head to make ...?

Well, you were told well, but it didn't grow

mimokd wrote:

I was told that if it rises, it's the ring's fault, so I gave up...

But they didn't tell you how much to increase the pressure after the oil test. And all your work in the dog's ass.

Does this mean that the valves or seals are leaking...?

Sealants only seal oil, not compression. Some valve does not close, or the seat is burned out, or the head is cracked in the vicinity of 1 cylinder.

You have leaky valves. A normal mechanic wouldn't put it on without even reaching the valves and replacing the seals, not to mention planning.

More like a repair head. You can try replacing the valves themselves. Remove the old ones from the low pressure cylinder, check for tight fit. Lap in the new paste, install new seals and springs. Check the tightness (e.g. with kerosene), how it will hold the head. If the engine has a high mileage, replace all seals in one job. When installing the tappet glasses, remove the oil from the oil chamber because you may have one of the valves ajar later. GOOD LUCK

Thanks everyone for the advice...
I'm getting to work...

Inspect the valve control hydraulics carefully. This is a common fault in these engines (as well as in 1.4/60 and 68 HP engines - there it is common ...).

But firstly, such an underestimated compression on one pot will not cause such strong symptoms as you describe, and secondly .... The error read is not related to this pressure ...

Check for left air, manifold, rubber connections, pneumothorax, EGR. Maybe you can tell us what the vacuum in the intake manifold is at idle.

If the pressure is well measured, the first cylinder does not hold pressure, and hence the uneven work and as zeimp wrote in his wisdom it may be the control and leakage of the valves themselves, and by the way, this repair and diagnosis is poplin, this knowledge was given to you by the butcher?

batigol66 wrote:

T5 show me where it says that he replaced the head gasket or where it says that the head was planed?

I'll write you back for my friend. We assume that since he was replacing the rings, he did not do it through the muffler, but took out the pistons through such four holes visible quite clearly after removing the head. It can also be assumed that no one in their right mind will put the head on the old gasket and without planning. So he replaced.

kortyleski wrote:

and without planning

And why is that? Only plan when needed.

kol ociz with such repairs as above, they unscrew as they please and the deformation is ready and ... and how to check that the adhesion curves? -these are the dilemmas of those who fix it -it's such a piece of metal eeeee it's definitely good, I'm not making fun anymore because kol.zeimp went to the moderators, he'll give me a banana

wopor wrote:

I'm still not laughing because kol.zeimp went to the moderators, he'll give me a banana

In your case, probably not, because the "mocking" you write about makes sense (we both know that), so cool
And that you can learn a lot on the forum (e.g. replacing the rings and assembling on the old gasket), it's a different story ... I'll wait for the author's response to the topic and it will probably be closed.

This is how I gather to describe the correct engine repair technology on my own. but on the other hand, there is so much on the web that I have an inner reluctance but it's good that they are like kol zeimp and other young people (probably young ) that they want me only "an old man and maybe" and we will probably never know what the author had in mind.

For a detailed explanation of the whole situation, I will describe what was done ...
New head gasket but no planning (I know what you're thinking). I got bad information for sure when it comes to diagnosis but now it's too late...
I did all the work myself so you can make fun of it - I'm abroad and that's why I'm trying it myself because it costs a fortune here...
How do I deal with the head, I will let you know if I succeeded and the pressure in the manifold, unfortunately, I do not know how it works ...

T5 wrote:

batigol66 wrote:

Replace head gaskets.

Did you read the first post? Do you think the rings are exchanged?

I know someone from the area who pulls the box and the shaft because it's cheaper (work according to g is supposedly not costs ) and the client pulls the gasket so "you can" .
greetings

przem27 wrote:

I know someone from the area who pulls the box and the shaft because it's cheaper (work according to g is supposedly not costs ) and the customer for the seal pulls so "you can".
greetings

My friend will write in what engine it was because I do not want to believe in such things.

The F9Q engine, it came to me a week after the ring replacement operation (supposedly), after passing the "crazy diesel disease" dictated by economics, the heart transplant only helped (along with the gearbox).
greetings

Maybe I misunderstood something. A colleague I wrote in the previous post that the latter pulls the pistons down after removing the shaft, right? But do I misunderstand.

That's what I wrote, embellished with sarcasm if my friend didn't notice, straightening, in my opinion, he did nothing but cashed the money, (because what about spraying the bottom of the piston? saying that he replaced the head gasket, he privately boasts that this is how he deals with naives. It seems to me that we just threw the topic in the trash with a stupid polemic on rhetorical topics, if your friend has any more questions, I suggest you pm me.
greetings

kol despitekd, at least I'm not making fun of you as a user, only from these "hit diagnoses", unfortunately, you need to acquire some knowledge and practice to give the most accurate causes of the fault, in real socialism I had to learn and gain practice and innovation in ideas on how to fix lack of some access to machinery and equipment for repairs, which sometimes caused a headache from brainstorming , now it's just a pleasure for me and work and access to info and gadgets (locks, etc.), and by the way, I once saw a repair of the replacement of the crankshaft in the former USSR performed in a ditch as a channel and after the repair the engine worked quite decently ZIL alone , Regards