Hello about a year ago i was here with a problem 

 

for summer the problem was gone but its back, when i start the engine sometimes...it knocks sometimes it doesnt i found out new things, when i removed the fault in diagnostics it stops, the knocking persist even if car goes down the road with no gas pedal meaning no fuel is added so its not a misfiring problem ? This problem also causes a "spitting" exhaust, the only thing that my mind cant comprehend that this problem is not regular, sometimes it does sometimes it doesnt, any more help would be really aprecciated since i changed all sensor etc that people suggested 

16555 is fuel mix too lean basic checks would be air intake leak/vaccum leak etc or fuel filter blocked. Could also be failed or leaking intake manifold gasket. Not sure if theres an in tank filter? I have had one break free on another car and float about causing air getting into fuel. Only did it when tank was less than 1/4 full.

Alasdair

3 hours ago, Alasdair1 said:

16555 is fuel mix too lean basic checks would be air intake leak/vaccum leak etc or fuel filter blocked. Could also be failed or leaking intake manifold gasket. Not sure if theres an in tank filter? I have had one break free on another car and float about causing air getting into fuel. Only did it when tank was less than 1/4 full.

Alasdair

I changed the fuel filter it has 1, also i changed the "vowen" part of exhaust right behind intake manifold, vacuum pipes also checked, i can check the manifold itself but if that would be the problem should it do it constantly and not just sometimes ?

If its the manifold I would think the fault would be present all the time unless its temperature related ie sealed when warm but not when cold which is unlikely the reason for 16555 code. Could be a faulty 02 sensor but I reckon that would put eng managment light on judging by the symtoms. 

The other thing it could be is the MAF but again I would think the eng manag light would come on. Sorry I cant think of anything else to check. 

Alasdair

I also changed the maf already that was one of the first sensors that was replaced 😭 cant believe that if a temperature related wrong fitment or something could cause such a problem thats unbelievable, the only thing that was not checked til now is the ramp that hold the sparks but...the car does that even when going down the road without gas =no fuel added =sparks dont go boom right ? It all lead to wrong combustion but at the same time it doesnt

Did you change the camshaft sensor and knock sensor either might be sending false info to the ecu. By what you have said you seem to have covered everything. Hopefully someone else on here will have an idea where to look.

Alasdair

 

Well after excruciating detective work...there was really a leak in the intake...yet small enough to be as you supposed temperature related it wasnt found the first time now we did...meanwhile my thermostat broke ...one of plastic hinges that holds the spring in place broke and left the spring half opened all the time wich made the engine run even worse but after it will all be done i suppose it will be all right again

6 minutes ago, DominikM said:

Well after excruciating detective work...there was really a leak in the intake...yet small enough to be as you supposed temperature related it wasnt found the first time now we did...meanwhile my thermostat broke ...one of plastic hinges that holds the spring in place broke and left the spring half opened all the time wich made the engine run even worse but after it will all be done i suppose it will be all right again

Glad you have something to work on and hopefully will cure it. My sons fabia 1.2 had a very slight exhaust leak between front and rear box. Last MOT its emissions were off the scale. Mechanic mate who is now an MOT tester sealed it up with some black sealant and it passsed no probs. Its amazing how a tiny leak can cause such major problems. 

Alasdair

Its really "amazing" it got on my nerves so much a ungplugged the injectors one by one ..the sound was almost the same but i could hear a little more struggle from the engine except one where the leak was ...i also checked if the injectors spray correctly and all ...damn such a little leak and so much trouble i assume that the leak also caused the 16555 fault where the lambda got the readings right but the system thought she is bad...now when i found it it all comes together like puzzle and im thinking why havent i knew this earlier

Well done for persisting and winning!