TOPIC: 2007 Chevrolet Avalanche with 5.3L Vortec Engine

GOT BIT BY THE COMPUTER AGAIN!!!

Made the mistake of believing that because the MPG reporting is built into the vehicles ECU that the information would be accurate.

Such is not the case. As long as everything is stock, the ecu can work with the numbers that it interprets through its operation. I know this because I tracked the mpg on this vehicle prior to the mod and the numbers were correct.

Last Monday, I topped off the tank, took a trip to NW Seattle and back, approx 72mi, later in the week to Sumner 34mi, Kent 54mi, one more trip to my Mom's 19mi and a little local driving... Total 205.1mi.

Topped off the tank this morning 8.875 gallons. Using the math calculation that we have all been taught to use... 205.1miles/8.875gallons = 23.10MPG

The ecu computations are reporting 15.4mpg average

Conclusion,

Don't trust the onboard ecu calculations to determine actual MPG after the mod.

Use the tried and true method, put the gas in... drive the vehicle, put the gas back in and do it by the numbers.

Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma

kARL YOU ARE CORRECT. THIS WILL HAPPEN AS THE WAY IT CALCULATES THE MPG. REMEMBER WE ARE CHANGING THE AIR TO TPS TO FUEL RATIO. DAN GADGETMAN MO

I was accepting the ecu display up until last night when I checked the trip odometer and did a quick calculation in my head... and that didn't come out right At the same time (multi-tasking) I thought about my comment on the "other forum" that the rpm's drop after the groove. Which also brought me back to the ecu, it is controlling the tach it isn't a direct read like the "old days".

It was somewhat of a global revellation on my part and answered a lot of disputed points as to "how" more than "why".

Pretty much makes my day

Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma

Re-grooved my backup TB for this vehicle... a bit more maticulous(?) about what I did and how.

For starters, as before, got the idle position. Plugged in the backup TB, set the plate at idle position, lightly scribed that point. Adjusted the plate position so the scribe mark was behind the plate, scribed again.

Then the fun part, determining where to scribe for the bit line. So I set the angle of the bit, with the opposing teeth resting on the plate, adjusted the plate to the contact point of the bit on the venturi wall and marked that.

Moved the plate back to the second scribe mark, and here's a tip for those that need a third hand to keep the plate in position, I took a half stick of modeling clay and pushed it into place behind the plate as a stop for the plate.

Put the groove on the TB at approximately 25 degrees following the third mark as the reference point for the bit. As the bit carves out the metal the bit follows the plate down into position.

Swapped out the TB and fired it up. This position gives the pedal a bit more room before it grabs the groove. I'll have some numbers tomorrow, need to take a run up to Issaquah.

Anyway here's the modelling clay...



and the groove





Karl Fortner
Tacoma, Washington

Almost forgot.... I now have the Gadgetman PLOP

Karl Fortner
Tacoma, Washington