This testcase was about seeing how much different fuel injector brands require a different time delay set within the PCM injector offset voltage time table and air/fuel multiplier table.

Installed in our 1999 C5 372 stroker engine was the GM C5R 42 lb injector. The fuel trims cells were right on at about 0% readings for the long and short term fuel trims

Thanks to teammate Mark D for donating his used SV030 36 lb injectors that we swapped in with the C5Rs.

First we did a tune making the injector flow with the difference of using stock 28 lb GM injectors to the 36s.
You see from the results in doing so the fuel trims were way too lean due to the makeup of this stroker engine.

We then made fuel flow changes in another tune to make up for that but fuel trims were still a bit too lean and testruns showed engine was sluggish.

We analyzed all the OBD data and then made changes to the injector offset voltage and air/fuel multiplier tables and tested that to find the internal coil of the SVO30 injectors required more delay time for the coil to react.

We the proper values put in those tables as you see those changes alone caused the fuel trims to get richer, the engine response times were better and the fuel mileage bettered by 2 MPG.

You also notice as the offset times were set to more suit the injector that the left/right fuel imbalance decreased

This clearly shows not all injector coil reaction times are the same and must be factored in when changing injector brands.

Attached Files svo30trims.jpgsvo30trims6.jpgsvo20trims1.jpgoffset.jpgfuelmult.jpg

Team ZR-1
True Custom Performance Tuning