VW Polo 1.2 code reads p0303 cylinder 3 misfire ?

[STUBAV]

vw polo code p0303 cylinder 3 misfire replace coil packs and plugs any ideas ECU RESET MAYBE ?

[zoki21]

inector chek

[catalinosonesti]

hy ,also check cabel to plug ,injector ,electic part s
wbr

[drz]

Need more info... How engine works on idle, does it have power while driving, etc. If all looks good, then you have burnt valve(s).

[catalinosonesti]

also can be piston, or bad compresion .....

[Meat-Head]

What an inbred, swap coil to next hole, repeat then if needed candle as well

#swapnostics. Coils are like £15

[volorucinski]

Sorry, but this is not about the coils. P0303 referes to a mechanical fault on this cylinder. Might be occured by injector clodged, bad spark, or bended valves, piston rings. If was a coil, p0353 occured. If was a broken injector wire, then p0203 occured among that p0303 and p0300. So... As I know about a lot of 3 cylinder engines...it must be a bended valve.
Before checking all that you want (wires, sparks, sparkplugs ect) think about making a compression test on every cylinder.
You can come back and tell us what the problem was. Maybe a distribution timing missmatch, either...

[Meat-Head]

Fairly sure P0303 can still be coil, swap it along seexwhat happenes

[volorucinski]

I bet on your experience, Meat-Head. Let's hear the man, after he does the whole check on the car...

P.S.: two days ago came a polo 1.2 (p0302) and a week agothis fabia 1.4 with the same errors. P0303. They came from different garrages after changing coils, injectors, changing map, pipes, vacuum leak tests ect. They came to change the ecu... And after codi g the new ecus, the problem remained. That I was telling them before doing that. I asked them about the compression test and both said I am joking, because the other garrages thougth it might be injector or coil problem. So... It confirms that after changing the ecuus, the problem stays the same. I don't do mechanics, so... They went as they came... Money spent for nothing, instead of doing a compression test.

[PhilipArt]

I can't believe that this is an issue related to software management.
You can try to change the coils order and check if the problem was moved to an another cylinder but if you have misfires on idle then you may have a mechanical problem and not electrical.
I suggest you to do a compression test first in all cylinders and if you find a difference between your third cylinder and the others (+/- 3bar difference according to VAG specs) then it could be a broken piston, piston rings, valves, carbon deposits... If that's the case, then you can do a leakage test to find out from where this compression escapes.
Now, if you don't have a tester to do those inspections, visit a garage to do those tests for you, because a lot of VAG's had issues with pistons and could be a huge/costly/catastrophic problem if you ignore it.

What's your engine code?

[swisstuner]

I bet on your experience, Meat-Head. Let's hear the man, after he does the whole check on the car...

P.S.: two days ago came a polo 1.2 (p0302) and a week agothis fabia 1.4 with the same errors. P0303. They came from different garrages after changing coils, injectors, changing map, pipes, vacuum leak tests ect. They came to change the ecu... And after codi g the new ecus, the problem remained. That I was telling them before doing that. I asked them about the compression test and both said I am joking, because the other garrages thougth it might be injector or coil problem. So... It confirms that after changing the ecuus, the problem stays the same. I don't do mechanics, so... They went as they came... Money spent for nothing, instead of doing a compression test.

100% agree with this poster. I might be new here but dont let post counts fool you. Theres a lot of swaptronics monkeys out there now who with a bit of money buy a tool, run a scan and send themselves and customers on a wild goose chase. Mechanicking 101 - first confirm there is NOT A PHYSICAL problem, then focus on the electronics.

[SDIracer]

Compresion on misfire cylinder no need to be drasticly low, 10-10,5 bar is enough.

In most cases inlet valve is problem.

[volorucinski]

Compresion on misfire cylinder no need to be drasticly low, 10-10,5 bar is enough.

In most cases inlet valve is problem.

I bet you are a good mechanic... I am not allowed to say that 10bar is a good compression, even if engines are different. But I am saying it: 12bars is a minimal treshold for an engine to work ok.. 17bars are for stock new. . At 10,you have some problems on that engines. Btw... We are talking obout compreasion test ade on cold, or hot engine? Wtf does anybody know about engines? I am not a mechanic... So i think i will let anybody brake his head on doing it.

When you check compression, it is measured on outlet valves compression, only if inlet valves are bended you will say that compression will be sent back to the intake...
. Ask ayone who knows about engines, and i am not speaking of sh*t garrages on your block corners... Nor the dealers. There are a lot of lacks and countries in need of good mechanics and electricians to do this job. On the other way, dtcs like p0301,
for example, ar referring to a problem on mechanical issue on cylinder no1. This problem can be generated by low compression(mechanical problem), injector not working, or even false air, fuel pump not injecting correct pressure into the regulator, or even sparks, spark plugs, coils or loosen screwed sparks, or even distribution mismatch...
always there will be other dtcs associated with this "mechanical error" that could be generated by electrical problems, false air, phisically mechanical problems or even more. I always said that i am an electronist, not a mechanic. But... I don'tcare if anyone spend money for changing ecuus or coils annd injectors because of a stupid garrage diagnose.[/QUOTE]

[SDIracer]

17 bar on 1,2 6 valve AWY engine?

ELSA says 10,8

Sincerely i cant remember when i see 17 bar on non motorsport petrol engine