Our 1995 Chevy Suburban K1500 4WD with a 350 received the Gadgetman Groove in April of 2010. Before the Groove the truck was getting 12 to 12.5 miles per gallon...two weeks ago, after a restriction in the intake air pathway, it reached 17.6 miles per gallon. A 40.8% gain in efficiency!!
This is very exciting because over the past year I have done the following to this vehicle since the Groove modification:
1. Plugged PCV, EGR and Evaporative Emissions exits from TB
2. Moved MAP intake further away from throttle body...since returned to original
3. Replaced leaky brake booster
4. Replaced IAC Valve
5. Repaired leaking plug in the intake.
6. Replaced intake gasket
7. Changed and increased gaps on spark plugs
8. Repaired/Replaced entire exhaust system to make it leak free
9. Installed then uninstalled an EFIE
During this year long process the truck did show gains in the 14 mpg or less range (most times closer to 12), so there was some gain. The 'burb seemed more smooth and powerful but I wasn't content with the efficiency gains.
Recently I dramatically reduced the intake air pathway and re-routed it farther away from the area of the Groove and that made the difference...17.6 mpg!
When you increase the throttle you can hear the Groove working as the majority of the air goes over the Groove now. Quite a sound
This goes to show, in the extreme, that the Gadgetman Groove is a process. Sometimes results are experienced immediately, but many times you need to work on the process before results are truly realized.
Very soon I will post a service bulletin to share with you all how to reduce the intake air pathway on all TBI units from 1987 to 1995.
Please post any questions or comments you may have concerning the Suburban adventure.