4l60e rebuilt, now terrible gas mileage

[BakedCookies]

Just recently had my 4l60e rebuilt due to the 2-3 surge that is so common. The transmission builder said he did all the upgrades that are on the market now for the 4l60e. Everything about the transmission seems fine now except it appears to downshift a lot more often than before. I drove the truck to work yesterday (it is not my daily) 24 miles round trip and used approx. 1/4 tank. My rough calculation has that to be around 3.8 mpg!! Before the rebuild I was getting around 10-11 mpg (33" M/Ts).

He did say he reset the computer, is this from the computer relearning or from the upgrades performed?

 

[rhino]

If you're only getting 3.8 a gallon something is bad off. Is it even shifting? whats the RPM? Is it higher at 50 MPH than it was before the rebuild?

 

[michael hurd]

You can't go by the gauge to figure out fuel economy... it's not an 'economy gauge'. The only true method is to start with a full tank, drive X kilometers / miles and fill the tank, divide the mileage driven by fuel used to figure out your mileage. At 3.8 MPG there would be fuel running out of the tailpipe....

 

[SCOTTYINWV]

That is true, but did he change the torque converter? Maybe it has some rediculous stall that's killing your mpgs?

 

[IOWNJUNK]

You can't go by the gauge to figure out fuel economy... it's not an 'economy gauge'. The only true method is to start with a full tank, drive X kilometers / miles and fill the tank, divide the mileage driven by fuel used to figure out your mileage. At 3.8 MPG there would be fuel running out of the tailpipe....

This^^^

Not sure a stock fuel pump would flow enough to get only 3.8 mpg.......

 

[BakedCookies]

You can't go by the gauge to figure out fuel economy... it's not an 'economy gauge'. The only true method is to start with a full tank, drive X kilometers / miles and fill the tank, divide the mileage driven by fuel used to figure out your mileage. At 3.8 MPG there would be fuel running out of the tailpipe....

Correct, I just noticed a very significant change in fuel consumption. I filled the tank to full and am in the process of getting a true mpg now. I do think the culprit though is the cruise control. I have not used it any on this tank and the mileage seems to be back to normal. I'll know for sure when I fill up.

 

[BakedCookies]

That is true, but did he change the torque converter? Maybe it has some ridiculous stall that's killing your mpgs?

According to the mechanic they rebuilt my torque converter.

 

[IOWNJUNK]

According to the mechanic they rebuilt my torque converter.

One phone call and that mechanic should be able to tell you what specs he rebuilt it to. At a minimum he should know what stall speed is.

 

[BakedCookies]

One phone call and that mechanic should be able to tell you what specs he rebuilt it to. At a minimum he should know what stall speed is.

I know, I want to have concrete evidence that there is an issue before I bother him.

 

[TylerZ281500]

is your torque convereer not locking at highway speeds?