Edelbrock E-Force With Bad Fuel Trims

[jxhunte]

2006 Corvette, LS2, 6.0L
Edelbrock E-Force 1593 Kit (549 HP @ Crank)
Kooks Long Tubes/High Flow CATS
NGK AFX Wideband
VMAX Ported TB
Crane 1.8 Quick Lift Roller Rockers

Just replaced my Ported 92mm FAST with Edelbrocks 1593 E-Force Supercharger. After installing the E-Force and upon initial start-up I noticed both STFT's & LTFT's running high. When I turn off LTFT's, STFT's for both banks 1 & 2 run at about 30%. With both STFT and LTFT active, STFT's will run around 3-6% and LTFT's will peg at 24.5%. However, this is only found at idle and when decelerating off cruising speed. I have checked for vacuum leaks performing both a visual inspection and the use of propane. I can't find any leaks.

I'm using Edelbrocks tune which is scaled due to the 2006 Corvette's ECM injector limitation of 63.5lbs/hr. All problems seem to be at or around idle. I have only put 44 miles on the E-Force for data logging purposes. Two files are attached. One file is of a scan while in park, setting in my garage and the other is of a 10 mile drive beginning at 7800 feet and ending in my garage at 9000 feet.

I appreceate any help/suggestions Forum Members may have in my effort to eliminate High Fuel Trims at idle.

[jxhunte]

I adusted Engine>Airflow>General Airflow>Airflow vs Freq Low from 1000 HZ thru 2350 HZ adding approx 30% to the value offered by Edelbrocks Base Tune. This brought my STFT's and LTFT's at idle to within 3%. I will now get the Vette out on the Parkway for MAF Calibration. I am surprised at how much I had to add to Edelbrocks offered values to bring STFT's and LTFT's within an acceptable range.

[BlkLS3]

This is very interesting to me as I have an 08 Vette with the E-Force. I don't understand why your tune is scaled as the injectors with the kit are the 52 (some say 56) # LS9 injectors. Did you change them?

I was seeing high duty cycles and had my injectors resized by FIC which required scaling, but never got that to work with my A6 trans and took them out. When I bought and installed another set of LS9 injectors , I used the injector Data Lingenfelter publishes for them. The Lingenfelter data has them at 56#. My duty cycles are a bit lower now. I currently run a BAP instead of a bigger fuel pump. If I still end up with high duty cycles I will go to a boost referenced fuel system as DSteck graciously advised.

I've also not gotten my MAF properly tuned yet, with injector swapping and some other issues. I'm attacking that next, but it does seem the Edelbrock tune is a ways off in this regard. I'm not seeing as big LTFT's as you, but I believe I'll be adding about 6 to 8%. After that I'll see if I can get my MAF corrected for WOT.

[jxhunte]

BlkLS3 - After reading your Post I pulled my Edelbrock Parts List for the 1593 Kit. The Parts List is generic for the 1590 - 1591 - 1592 and does not list the 1593. However, the Injectors listed are 52 LB/HR. Until your post I had no idea what size injectors were provided with my kit. I assumed they were larger than the VCM's limitation of 63.5 lb/hr and thus the reason for the scaled tune. When I completed the install and before I loaded Edelbrock's Tune I contacted Chris Johnson (Edelbrock Calibrator). Chris indicated the latest tune was scaled because of the VCM limitation of 63.5 lb/hr. I will now contact Chris and ask why the scaled tune if my injectors are truely within the parameters allowed by the VCM. Thanks for your Post - jxhunte

[BlkLS3]

Very interesting indeed. Keep us updated.

[jxhunte]

A contributor on another Forum (yonson) indicated the scaled tune is the result of an Airflow limitation and not an injector size limitation. If I learn more I will post info here.

[jxhunte]

I received the following from Chris Johnson of Edelbrock: "While there is a limit on the injector size you can use (scaling can fix this issue as well), there is also an airflow limit of 67.5 lb/hr, anything over this and the PCM does not know how much fuel is needed so it continues to supply the same amount as is being requested at 67.5 lb/hr even if you are actually making 80lb/hr airflow. When you scale the calibration (I used 25% for this one) what was once 67.5 lb/hr, the PCM now thinks is actually 50.625 lb/hr. So now with the 25% scaling we can actually make 90 lb/hr of airflow before we hit our limit. Your DIC is going to be 25% off as well as any airflow monitoring you do with HP tuners. So just remember when looking at the airflow to add 25% to it for the actual airflow being used." Thanks Chris of Edelbrock!!