New injectors require tuning the intake calibration

RainMaker · 09-17-2006, 07:04 PM

Hey guys,

I can only guess its because of the different injectors reacting to manifold vacuum differently, but after switching to JECS 720cc injectors from the Perrin 816cc'ers, I've had to make some pretty drastic adjustments to the intake calibration. I used Wolfplayers/Christian's latency values (which helped smooth these injectors out considerably), and then had to lean out the 1-2 volt area (to the tune of a .80 multiplier), richen up the midrange 2-3 volts about 10%, and then adjust WOT about 3% (all in a pretty, smooth way).

So if you change injectors, even between flow-tested ones like I did, and you have the scalar and latency values down pat... you will still need to revisit the intake calibration. I did a search of old JECS tuning posts, and history seems to agree.

It really seems odd to me that Subaru uses a single scalar. Even GM LS-1s require a map of flow with vacuum/pressure across the injector mapping to flow. Is the fuel pressure connection to manifold vacuum so perfect that Subaru can ignore it? hrm.

09-17-2006, 07:04 PM	#1
RainMaker The Next Petter Solberg Car: 08 Z06 Corvette Fav Mod: Jack Jack Location: Portland, OR Posts: 883 Join Date: Oct 2005 Trader Rating: (3)	New injectors require tuning the intake calibration Hey guys, I can only guess its because of the different injectors reacting to manifold vacuum differently, but after switching to JECS 720cc injectors from the Perrin 816cc'ers, I've had to make some pretty drastic adjustments to the intake calibration. I used Wolfplayers/Christian's latency values (which helped smooth these injectors out considerably), and then had to lean out the 1-2 volt area (to the tune of a .80 multiplier), richen up the midrange 2-3 volts about 10%, and then adjust WOT about 3% (all in a pretty, smooth way). So if you change injectors, even between flow-tested ones like I did, and you have the scalar and latency values down pat... you will still need to revisit the intake calibration. I did a search of old JECS tuning posts, and history seems to agree. It really seems odd to me that Subaru uses a single scalar. Even GM LS-1s require a map of flow with vacuum/pressure across the injector mapping to flow. Is the fuel pressure connection to manifold vacuum so perfect that Subaru can ignore it? hrm. This ad is not endorsed by this member. Please register or login to hide this ad.