Quest for good fuel economy. 5 litre auto

[Haydz]

Hey guys.

since getting my exemption. i have realized its been using a fair bit more fuel than what other people have reported their cars of the same type use.

so here is what i have done so far.

1. Cleaned the Throttle body IAC etc
2. Replaced the oxygen sensor
3. Got 10mm leads
4. New Spark Plugs

Still yet to put the new plugs/leads in. and i have a bottle of Nulon injector Cleaner to go in.

since replacing the oxygen sensor my fuel economy has gone from 20.5l/100km down to 18.4l/100km

so im hoping the rest will fix it up to a more normal level.
just wondering if there is anything else anyone can suggest to make it a bit better.

the car is also going to get a wheel alignment. as it pulls to the left a bit.
this is also for anyone who needs to cure there fuel economy problem.

 

[hsvpunk]

WTF 20 per 100. :bang:
Something is seriously wrong with your car dude. (hence thats why your here)

I still cant belive 20 per 100,sorry 18.4 per 100.
How do you drive, road wise highway, country?

Im lucky to hit 14 per 100, and i do atleast 300-350kms a week. and thats highway, and stop start trips to amtes houses and shops.
I cant say ive seen anyones that high.

Maybe Mr Foam could share his thoughts, could be tune?

 

[greenfoam]

The standard tune will do alot better than 18l/100. With a tune you can see a improvement of 1-2L/100 maybe 2L but 1.5 would be more typical I'd say. The whole Coolant sensor/ECU coolant circuit and thermostat areas are where you want to be looking for the problem and also the fuel pressure regulator. It _should_ use *just* under 10l/100 on a tune on the highway and maybe 11 without one, worst case. If it's 12 or 13 on the highway then it has issues that need some fixing, My VP goes about 650kms on a tank, mostly highway so it does still chew the juice considering the size of the tanks in these things but they are a bit thirsty engine after all

 

[Haydz]

ok guys.

well my driving is

most of the time under a quarter throttle. maybe 25-50 kays of the 350 or so. under heavy acceleration.

greeny. i spoke to wavez about getting a tune from you. probably be next pay day now. i splurged and bought new plugs and leads.

Ok. anyone know how to test the coolant temp sensor? or just buy another one and hope that was the problem?


not much highway in sydney.

that was reset with a full tank of petrol.

 

[VrWagz1]

Haydz just buy a new coolant temp sender unit, its not worth the effort to test them and its a fair chance it will be the problem. But thats bad fuel economy, im doing heaps better than that in my wagon which would be a similar weight. Do the plugs definatly, you will notice a nice little power increase if your old ones are worn and make sure they are gapped to specs too.

If your running non stock wheels, do a check on your cluster to make sure the k's are clocking up close to what they should be. You got any of those 1 - 5km odometer check things on the freeways near you. If its out you can calibrate the dash to read right again pretty easy. It will help make sure you fuel readings are accurate.

 

[clubby_you]

with alot of city driving (ie me going to work ) was pretty common for my clubby to be around 18l per 100 with full throttle being used like 3 times a week in traffic these things are terrible since putting the manual in i have been driving a bit harder and am now around 14.7 to the 100
I have seen 20 - 100 km when i was sick one week and i was just driving in peek hour to and from home to pick my missus up

My advise get a manual

 

[Haydz]

this traffic was not peak hour. as indicated by my average speed. its a bit of both. traffic lights to 60-70 kay roads. with a bit of a blat in for good measure.

im going to call peps now and get a price for a temperature sensor. and if its not to costly ill buy it if not it will have to wait till later



Edit: 25 bucks from Peps auto spares

 

[greenfoam]

I see your speed average is 30 ks, my average speed is about 80 for lifetime of the car while I've had it, so that's a pretty big difference. Not sure how I would go putting around in heavy traffic like that, I don't think I'd have a car over about 1.8 litres if that's all I was doing

 

[paulsautoelec]

put negative lead of multi meter on neg battery clamp pos in radiator water/coolant with engine running . a reading of no more than 500mv should be observed. any higher voltage and youhave electrolisis problems. flush cooling system replace with gm coolant and distilled water. you will be surprised at the difference it can make

 

[STEALTHY™]

Convert to manual. Job done.