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In my efforts to develop a great tune for my LT5, I had taken my 16(1 primary/1 secondary) injectors to be flow tested. and from this flow test I paired injectors so as to give me as equal a fuel distribution as I could. And I can say that that effort has resulted in a motor that runs smoothly, even with lumpier cams on intake and exhaust. However, the "split BLM" presents itself especially at idle.
I have attached an .xls that shows the flow rate for each injector as it was previously installed. Then I modified the injector config(pairing) so I could get much closer to equal fuel distribution to all cylinders. For those not familiar w the LT5 fueling, the motor used one set of injectors to run, idle, cruise. When Full Power was initialized using the Valet Key, the secondary throttles would open allowing more air into the cylinders via a second set of runners. Along w that was a secondary injector to provide fuel for the extra air. In reviewing the .xla I noticed that I could re-organize the injector pairings in such a way a to provide additional fuel at IDLE to the left bank than to the right bank. My thought is that this may help in enriching the left bank while leaning the right bank and thereby bring the BLMs closer together at IDLE which has the greatest BLM disparity between the two banks.
The .xls attached shows the original injector, the pairing I currently using, and finally the ALTERNATE pairing that I am hoping will bring BLM at IDLE more in lin bank 2 bank.
SO I am curious to see what the "brain trust" here on 3rd Gen thinks of this approach.
Last edited by Dominic Sorresso; Oct 13, 2023 at 06:10 PM.
Spreadsheet appears to be available. Basically, I am proposing to swap injector pairs so that the injector flowing the least in each pair will take up the primary position, while the greater flowing injector will now sit in the secondary spot. The result is that the left bank injectors will flow a bit more than the right bank injectors and I am hoping that will bring left/right BLMs at idle into closer alignment.
Just to clarify, on the LT5, idle is fed by only the primary injectors. The secondaries come on off idle and the ECM reduces calc’d PW by 49% essentially maintaining the overall fuel flow but now the cylinder is fed by both injectors.
Makes sense what you're proposing. If I remember correctly (by plug reads) it is actually the rear cylinders that are effected the most. Would be 7 or 8. I would try putting the higher flowing injectors into the rear two cylinders on whichever side is leaner. It will be interesting to see your results.
In my case, its the P/S bank that runs rich and/or is burning oil. The first pic is of #2 and 4 on the passenger side, while the next 2 pics are of #3 on D/S.
