Bad Fuel Economy

[tiersum]

hi all big problems with fuel economy isnt even reaching 300km around the city and it isnt getting booted car has extractors and a full exhaust and runs on vortex 95

vs commodore equipe 68,000km serviced recently maf throttlebody and airfilter cleaned

new

oil filter
fuel filter
injectors
sparkplugs
leads - - - - - 15,000km old
oxygen sensors x 2

im all out of ideas on what to replace to fix this problem tyre pressure is checked weekly and its 36

[HoldenOnn]

What temp is your car running at? Very hard question to answer apart from saying what the gauge reads. Thats why its a good idea to go into Holden or Auto Electrician who can plug into computer and tell you the exact temp as the car may not be reaching operating temp due to faulty thermostat or Coolant temp sensor malfunctioning.

It probably may be numerous little things also instead of one big thing, but could go either way.

** Wheel alignment ok?
** What grade oil are you using?
** For a VS to have only done 68,000kms, thats very low. Maybe internals are glazed or carboned up?
** Are the new plugs NGK or genuine? What gap?
** Are the new oxy sensors genuine?
** Whats coolant look like? When is the last time it was flushed and new thermostat?
** Have you had someone connect to computer with tech 2 computer or the like and check for computer error codes? If not, why not? If so, any codes?
** Vehicle manual or auto? Whens the last time the Auto was serviced? or if Manual, is the clutch slipping? If not slipping, how can you be sure, how are you testing it?
** Using all genuine products eg fuel filters etc
** How are your brakes? Not grabbing at any time? Handbrake not too tight (although smoke would most like have resulted through heat already on this one)
** Any exhaust or extractor leaks? How have you checked for this?
** Hows your air filter? Any dirt or restrictions on intake piping before and after air box?
** Fuel trims can get out of wack and the only way to rectify is to get a computer connected and reset fuel trims (my auto elec did this on my VS)
** How old are your tyres. Are they originals with only 68,000kms on the clock? Whats the rolling resistance. This question about rolling resistance can't be answered, but if you look at the manufacturing date on the side of the tyre, if they are over 6 years of age, then I would change.

I have just recently sold my 1996 VS SII S Pack Commodore 5sp Manual only 6 months ago after owning for 3 years. I used to get about 450-500kms per tank on city cycle. This was truly a city cycle as I live less than 3 kms from work and the car wouldn't even reach operating temp which is the same as my new VZ Calais which coolant only reaches 77-80 degrees celsius before I get to work. Plus I go home for lunch and back to work. So this is truly city cycle.

On highway cycle I would see 750kms and up to 800kms to a tank cruising with cruise control at 110km/h.

Figures of fuel economy are accurate as I used to reset trip on every fill up and then on the next fill I would divide the kms travelled by the litres used. Then multiply tank volume by kms/litre and arrive at the amount of kms I would get if I drained the tank totally.

Speedo and Odometer on my VS was correct as was tested with various GPS units over the years of me owning it.

Goodluck with it all,
Matt

[eXphoid]

Hey thanks HoldenOnn, will certainly take a look at that list when I get back to work on my vehicle.

[DannyboyDS]

dont forget to check for fuel leaks too, my VS V6 was getting 350kms to a tank of highway driving, turned out that the rubber hose that goes from the tank to the filter had a small split in it, after that was fixed I gained 100kms to a tank.

[tiersum]

hey mate my tyres are new and have been replaced 19's but the car was getting 450km out of a tank with the 19s on so im not sure whats causing this

[HoldenOnn]

How did you go with the checks and fuel economy now?

[KwaVR]

i have a 1994 VR with about 350,000kms on it and am only getting about 300km's in city driving. the temp guage never goes above 1 bar and it idles at about 700rpm. i brought it to my mechanics attension at the last service and he just said nothings wrong with the car. i would like to know if you get your economy sorted tiersm. im considering a holden auto technician next time.

[CU5H1NG]

hi all big problems with fuel economy isnt even reaching 300km around the city and it isnt getting booted car has extractors and a full exhaust and runs on vortex 95

vs commodore equipe 68,000km serviced recently maf throttlebody and airfilter cleaned

new

oil filter
fuel filter
injectors
sparkplugs
leads - - - - - 15,000km old
oxygen sensors x 2

im all out of ideas on what to replace to fix this problem tyre pressure is checked weekly and its 36

Same problem with me. im loosing fuel aswell but i didnt know how. then i could start to smell fuel from the back right wheel arch. found out that from wear and tear, my lines have cracked so everytime i go around a corner it drips out getting it fixed today with brand new breather hoses, etc. only thing is my VS has 188xxx on it lol

[inais]

mines got 320,000 on it, have never been above 350 highway or city. Hope you get urs sorted out. I would probably try a bit of throttle body cleaner, and possible try the little blue tub on nulon i think its called. Add that to your fuel system.
After all the work you done on it, it should be better than it is. Could try fuel pump too.

[Nervegas]

I had my mechanic look at mine after i installed a larger throttle body and he found that the cruise control cable was too tight and holding the throttle body slightly open. now it idles at botu 900rpm rather then 1300 when warm.

[pillzor]

i gained an extra 70kms on the highway after putting a new coolant temp sensor in, thats from 380ks from full till petrol light too 450ks.
also an oil change and new plugs and oil filter.