fuel economy question

[TI0350]

G'day All,
I've got an auto VS V6, My tranny needs rebuilding as well but only slips from 1st to 2nd and as long as Im light with the peddle it doesnt rev that much before it changes..
I've noticed that my fuel economy has gone to crap lately getting 320-330 out of a tank instead of the 380 to 410 In used to get..
My question is could it be my tranny thats making my fuel economy go down by so much or could it be something else like the o2 sensor combined with the tranny..

 

[mattman]

tranny shouldnt do that much unless its either revving high, or slipping a hell of a lot.

Sounds kinda low... I got 450-500 out of my old ecotec..

 

[TI0350]

nope not game to rev it too much the most it goes is 3000 thats on a hill start as I need to get a little bit of speed up to take my foot off wso it can change most of the time thought I dont let it go above 2000..

 

[hako]

Out of interest, does it still slip when you manually change it from first to second?
I normally get 400km from a tank which is not 59L but about 48L (when the low fuel light comes on)

 

[TI0350]

never tried manually shifting it.. All my driving to is in the city hardly any hwy driving at all..

 

[kopper69]

I dont think its good for the auto box to be shifted manually. Was told by another member a little while ago that it puts the wrong pressure in the wrong place at the wrong times - > earlier failure. I have a VR acclaim (non ecotec) and I calculate that I can get about 550kms out of my 63L tank on an average week. Lately (recently made some changes) now seem to be getting at least 600kms. Check error codes. DONT go changing O2 sensors until you have the tranny fixed. Get the tranny fixed and see how your fuel goes. If that doesnt solve the problem start off with the cheap things. I changed my oil from magnatec to GTX2 20/50 (a thicker oil) and a new filter and found that made a big difference. Even better than the $130 odd i spent on a K&N filter with cleaning kit. My experience with O2 sensors is that they dont "half fail". They either fail and give you problems or go fairly accuratly.

 

[TI0350]

Same oil I use...
I pretty much thought it was the tranny tell only got got 220 out of the last tank but that was regular unleaded my car seems to drink that faster then 95 real weird...
I wont manually shift it dont want the tranny to die hoping it will last til the end of the year when I getting rid of the car rather put the tranny money into a newer car..

 

[inwiththenew]

try changing coolant temp sender

 

[TI0350]

where is it..
Dont worry i looked it up in the manual forget that too big of a job for me

 

[Slow VR]

Ive changed 02 sensor, both coolant sensors, replaced injectors, cleaned TB, service the K&N!! Got extractors, 2 1/4 exhaust with new mufflers..... Ill be stuffed if i can get over 400klm on a tank with city driving like a nana.....The fuel economy has not changed 1 bit after doing all this on an engine thats done 260 tho klms.