Fabia Misfire

[stevet1962]

Hi everyone, new to this site We have an identical problem with out Skoda Fabia 3 Cylinder, engine code AZQ. It will run sweet on tick over, but as soon as the revs are taken above 2000rpm the engine management light flashes then after a few seconds it will cut out the injector on that cylinder. We had the vehicle code read andf the code 16685, cylinder 1 misfire detected came up. To date we have: Swapped and replaced all three ignition coils.
Swapped from number 1 cylinder to number three cylinder the fuel injector.
Have had the ECU checked by BBA Reman, all ok
Replaced spark plugs
Swapped injector wiring from 1 to 2 cylinder
had wiring checked between injectors/coils and sensors to the ECU
Had the cylinder head removed, valves lapped in & guides replaced
Timing chain & guides replaced. We have recheked the timing
Replaced cam & crank sensors, knock sensors and front lambda sensor.
Compression test carried out, all the same
Smoke tested inlet & vacuum system
Leakage test on valves/cylinders all ok

I have now become bald with pulling my hair out, can anybody please shed some light on this problem.

[ColinD]

I've moved this to the fabia forum. Hopefully somebody wiser than I knows.

 

Although your attempts appear comprehensive. Lets cross our fingers.

[Ben Cordy]

I had a cylinder head misfire on the same engine but unfortunately my was solved by one of the things you've already had done/checked. Hope you find a solution but can't think of anything else that could explain it! Given what you've already spent there are a good few low milage replacement engine going (at least there were the last time I checked).

 

Shouldn't be too big a job given how dinky and simple the engine is! 

[xman]

Could be fuel starvation, have you changed the fuel filter? A faulty fuel pump might also do the same - can you check the fuel pressure - I recall there is a schrader valve on the fuel rail .

 

Normally, misfires are usually down to faulty coil packs and/or plugs.By moving the coilpak/ plug/injector to another cylinder you would see the reported error move to the other cylinder - bear in mind that misfire errors require a number of restarts and a minimum amount of engine running time before the ecu clears them down so you may initially see errors reported on 2 cylinders.

Edited 31 July, 2014 by xman

[Jabozuma]

Check the plug gaps and set them to 0.7mm. Have you got a photo of the original plugs you pulled from the engine?

Check earthing strip.

Have you had full engine running log recorded and analysed. I'd check all engine parameters at and around the misfire events to see if there's anything in the data explaining what is happening. Especially lambda readings, fuel rims, fuel pressure, intake airflow. Exhaust gases readout is helpful as well, check for CO2, HCO and O2.

Exhaust headers not damaged?

[Ootohere]

Electrickery is all magic to me, i have not a scoobie.  

 

But from the list of all already done.  Earthing could well be the problem.

 

Is all the various things done in the list by more or less one person, because if it is, 

i would have a fresh set of eyes and mind go over everything to see what has been missed.

Timing checked again as one of the first things.

 

george

Edited 1 August, 2014 by goneoffSKi