poor gas mileage?

XxKHxX · 11-15-2005, 09:01 PM

i think im average 18 mph...auto 944...mostly constant 45 mph driving. i even tried not pushing the gas hard..any suggestions? maybe a bad o2 sensor?

right now im using 91 octane..and im going to switch back to 87 after readin up on it...

Zero10 · 11-16-2005, 07:42 AM

Disregard what the gas cap cover says, no need for 91, that will save you a little bit on fuel. Next, if you don't know when the O2 sensor was last changed, change it, look for vacuum leaks, etc.
Start with basic tune-up stuff (plus O2 sensor) then go from there

I got 10L/100km in my 86, which I think is around 26mpg?...
That was doing pretty good considering it was 100% city.

Techno Duck · Techno Duck's Garage

I concour, run down the list of basic maitenence items.

Air filter
Cap and rotor
Ignition Wires
Spark Plugs
Fuel Pressure Regulator
Fuel Filter
O2 Sensor
Vaccuum leaks
Clean and flowtest fuel injectors

I get about 19-20 city in my '87 that has the FRWilk chip. I have gotten about max 23-24 highway with it. Using stock mode, i can average about 24 city and 26-28 highway. I have changed everything on that list above with the exception of having the injectors cleaned and flow tested. That is next up on my list to do before the end of the winter.

Zero10 · 11-16-2005, 10:39 AM

Highway mileage should be ~30mpg, give or take a couple. One time in my N/A I set a record though... I got the best mileage ever known to an N/A, or so I like to think.
I did 1065km on 61L. That was not typical, but it was very impressive. It involved driving 90kph on the highway while tailgating a motorhome. I damn-near could have shut it off and coasted home

erics944 · 11-16-2005, 11:22 AM

I get ~25 with my auto

tgcattle · 11-16-2005, 11:41 AM

i can't seem to keep my foot out of it. I drive to fast. still get bout 350 miles to the tank.

Techno Duck · Techno Duck's Garage

You might try drafting behind other cars. Gotta cut down on that wind resistance you know.

My gas gauge is a little whacky, only reads 3/4 full on a full tank. When the line hits the last mark on the gauge i am usually at about 300-325 miles. I figure i could do another 25-50 before it runs dry.

Eldorado · 11-16-2005, 01:27 PM

hey techno, my gague is the same... at full, my gague only reads 3/4.... when the gas light comes on, i tested it one day to the point where the tank ran dry - and that was almost 150 miles after! lol

Dougster · 11-16-2005, 03:15 PM

My gas gauge does that too, well just over the 3/4 mark...
I got 521 miles on a tank 95% hiway, with the mark slightly lower then "empty" & I filled her up, I got like 17.6 gal back in...(21.5 gal tank)

Techno Duck · Techno Duck's Garage

Im scared to run the tank down all the way, have heard of people killing fuel pumps by sucking up all the sediment in the bottom of the tank. Maybe this weekend ill let it get a little lower than usual...ill take a chance and let the light come on this time around.

Im actually thinking of pulling the gauge cluster again and tweaking the needle to read full.

toolboy62 · 11-16-2005, 05:08 PM

I don't think I've ever seen my low fuel light come on. It doesn't bulb check, and neither does my overtemp light. Same behavior noted with two different gauge panels and also checked the little bulbs to make sure they were good. Whiskey Tango Foxtrot, over? Looking at the traces on the back of the gauge panel it appears that the bulb check function works through diodes and the diodes all check OK as well. (Or are the diodes for the ! light? and I'm barking up the wrong tree?) I'm 100% clue free... do these lights have a different ground connection than the rest of the panel?

Gauges all work OK FWIW as do the oil pressure and low voltage warning lights. Well, except for my oil pressure gauge which is completely undamped; I was going to replace that gauge with one from my "spare" panel, before it disappeared into a vacuum with my bigass Milwaukee drill with the 1/2" chuck, which I am not happy at all about losing. I still suspect my landlady's boyfriend of inadvertantly grabbing the box that had all that stuff in it... but I digress.

nate

Zero10 · 11-17-2005, 12:19 PM

Quote:

Im scared to run the tank down all the way, have heard of people killing fuel pumps by sucking up all the sediment in the bottom of the tank.

Stupid comment, but it always draws fuel from the bottom of the tank. Any sediment down there would get sucked through anyways, regardless of running it right down...

There is no check on the low fuel light, same as the overheating light. You have to make them come on to see if they work