1.4 TJet accelleration issue - knock sensor?

[573v0]

Hello all,
I have Bravo 2008 1.4 TJet with 88kW and ~110000km. I own the car last 30000km and from the beginning the car's movement was a bit jerky, but only around 2000rpm and under really low load (cruising 30km/h on 3rd gear), so I didn't really pay attention to it. But last 300km it got much worse, now the engine is kicking when I try to accelerate. I have also LPG in the car (aftermarket), but I disconnected it so I could make sure the issue isn't there. I replaced spark plugs (the same NGK model, as recommended by the manual), spark coils (all 4 of them) and MAP sensor. I also did reset of adaptive parameters in ECU and recorded few parameters during my test drive, but for some awesome reason I cannot post YouTube link here, until I have at least 5 posts :bang:. So for now, just screenshot. Sorry there's no speed info, as MES didn't get this info from CAN.. mostly I drove 90-130kmh on a freeway.


Only thing that I found disturbing is Knock control being active whenever I try to accelerate, which may stand for misfires, but I didn't see any error code in ECU. Only error I got there is P0576 - Cruise Control, but I guess ECU just found out something went terribly wrong with the engine and it turned CC off.. but nothing else related to this knocking.


Does anyone have any clue, what may be an issue here?

Thank you.

 

[573v0]

Hi guys,
so far I didn't find the cause. I watched my recording of MES over and over again and it's visible on lambda values, that there's a lot of oxygen in the exhaust (lambda goes to 1.08 when during acceleration). I was advised to check fuel pressure sensor on fuel rail and also fuel pump, as there's no other sensor checking it's proper functionality and it could explain the lack of fuel during the combustion (although, injection time was ~9ms highest, I don't think that's the injector's maximum, so even with lower pressure it should be able to extend the injection time to get enough fuel into the intake).


But maybe there's something wrong with MAF sensor? On the provided screenshot, there's Air quantity over 1000kg/h when accelerating and never goes under 300kg/h when idling, that seems to be extremely high value, if I understand this correctly: 14.7kg of air needs to be mixed with 1kg of fuel, which means 300kg of air needs to be mixed with 20.4kg of fuel. That would mean, the average consumption on idle would be ~14 litre per hour, while usual value is around 0.5l / hour. Can someone confirm this way of thoughts?


But even if the sensor would be faulty, in that case ECU would think there's too much air and would try to enrich the mixture with more fuel, which would result into too much fuel in exhaust, so lambda would go far under 1.00..

Right?

Thanks