Cause of incorrect lambda reading ?
Cause of incorrect lambda reading ?
(OP)
I'm having trouble pinpointing the cause of a puzzling situation. I'm working with a GDI engine and using an injector with a sub optimal spray pattern which I believe is causing excessive cylinder wall wetting. Cold start is very bad. At WOT the engine's wideband lambda sensor is outputting a reading significantly richer than flow bench data for the injector suggests would be possible. Flow calculations based on lambda and air flow readings exceed the flow bench by ~12%.
Could the incorrect spray pattern cause the lambda reading to be incorrect in the rich direction? My initial thought is that a bad spray pattern would result in unburnt fuel which should result in a leaner than expected condition, but this is not the case.
Could the incorrect spray pattern cause the lambda reading to be incorrect in the rich direction? My initial thought is that a bad spray pattern would result in unburnt fuel which should result in a leaner than expected condition, but this is not the case.





RE: Cause of incorrect lambda reading ?
MS
RE: Cause of incorrect lambda reading ?
RE: Cause of incorrect lambda reading ?
What is the fuel composition? Any ethanol or oxygenated fuel?
RE: Cause of incorrect lambda reading ?
I should also mention that another injector was tested that had an appropriate spray pattern for the application. It showed a higher flow rate on the flow bench, but resulted in leaner lambda values with the same fuel pressure and injector pulse times.
The engine is also turbocharged. One theory I have is that the excessive hydrocarbons in the exhaust created by the poor spray pattern are being concentrated towards the outside of the exhaust stream due to the centrifugal forces created by turbine. This could created a richer mixture at the tip of the lambda probe, however I have not found any published data to support this theory. Does this sound at all plausible?
RE: Cause of incorrect lambda reading ?
I'd think the turbine would mix the exhaust gases enough to be homogeneous.
RE: Cause of incorrect lambda reading ?