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Injector Change


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Hey guys,

Having an issue with fueling that I can't seem to figure out.  I'm probably just spacing out on something since it's been a while since I updated all of the input settings needed for injectors.  Anyway, I'm running a Vi-PEC i88 ECU with the latest firmware and using the latest version of the Link G4+ software.  The car is an Audi B5 A4 4 cylinder engine.  Trigger settings are perfect.  The ECU is setup using the modeled fuel equation.  I had it tuned for high-z 1000cc injectors.  Recently though, I installed high-z 2000cc injectors.  I input the information I believe is necessary to get the car running on the 2000cc injectors.  I input the exact flow specs provided by the data sheet for the injectors (2279cc/min according to the data sheet) and I input the fuel pressure that the flow for these injectors was rated at (43.5 psi, 3 bar).  I mechanically adjusted the fuel pressure to meet the rated pressure (was set at 72.5 psi, or 5 bar; now is at 43.5 psi, or 3 bar).  I also updated the Injector Dead Time table with the values given on the data sheet for the 2000cc injectors.  Beyond that, I changed no other parameters (fuel table, etc.) just so that I could get the car running.  I know the fuel table will need adjusting, but it shouldn't be too far off.  It started up pretty rough (rich) at cold start temperature (currently 80-90 degree Fahrenheit, or 27-32 degrees Celsius) and ran very rich during warm up enrichment (I understand it will need some calibrating/adjusting of the enrichment setting).  At operating temperature, it was still very rich, but I adjusted the fuel table a little, and it now idles fine at 1 lambda.  But, when driving it starts to run very lean at points in the fuel table that it was running rich on the 1000cc injector tune.  For example, in the range of 5-10 psi MGP (BAP reads 14.7 psi, sea level, so MAP would be 29.7-34.7 psil) under partial throttle, on the 1000cc injectors, lambda was reading at about 0.7-0.8, depending on the requested lambda; but on the 2000cc injectors, it is reading at about 0.9-1.0, which is far off from the requested lambda.  No changes were made to the fuel table and increasing the fuel table numbers puts them at almost max and lambda is still reading leaner that I would like.  Fuel run for both injectors is about E50.  I have a fuel pressure sensor installed and fuel pressure is normal.  Unfortunately, I was not able to get any logs of the car running/driving with the 2000cc injectors installed.  I have attached the current rough tune file for the 2000cc injectors as well as the last tune with 1000cc injectors for comparison, in case maybe I missed a parameter that could be causing the current lean issues with 2000cc injectors.  I also attached a log file from when the car was running the 1000cc injector tune to show how the car was running before upgrading the 2000cc injectors.  No other settings and tables have been changed.  So, boost settings, ignition settings, etc. are all the same.  I'm just looking for some insights about what I could be missing, or some ideas of things to check.  I did test the injectors with the basic output test and all 4 injectors tested fine.  I also double-checked the impedance of the injectors after driving with them to make sure nothing happened to them.  As far as I can tell, they are okay and the impedance measured matched the impedance listed on the data sheet.

Audi A4 Race Car E50 2000cc Injectors 8-16-2019.pclr Audi A4 Race Car Ethanol Gas 7-29-2019.pclr 1000cc Injector Log.llg

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I think the "running rich" around idle and warm up could well be explained by the new injectors operating probably well into their non-linear region.  However I dont have much to offer as to why it would be running significantly leaner at higher loads unless they dont actually flow what they are supposed to.  I dont see any obvious mistakes in your fuel settings.  Im not a fan of the CNG injectors as a lot of people see large variations in flow with fuel/injector temp and also a decrease in flow as they age, but dont have much personal experience.

Check the basics such as the MAP sensor is still reading correctly, but otherwise I would be doing a check injector test in a jug or similar to confirm flow rate.

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