using more gas

[cazzz12000]

Hi guys got a 93 3.5 taken out to 3.9 with a cam so I am not expecting great fuel economy but in the last few weeks the gas km's have dropped from 230km down to around 170/180 can anybody give me any idea why(plugs are about 2.5/3 kms old thanks zacc

[ladas]

Is that 2.5/3,000 kms or (plugs are about 2.5/3 kms old)

[ladas]

Timing can be a major issue - has that been checked

[100I]

alonjg the same lines - checked your air filter?

[Mark86]

i just had my gas tuned ( adjustment of mixture) because i thought mine start using to much gas not as dramatic as yours but noticeable. Was told good idea to make slight ajustments for winter/summer. My 86 is now a 4 litre
with torquemaster camshaft with extractors and is only 10000k old until it was about 5000k it use pretty heavy on fuel ( if your engine is new ?).

All the best Mark

[LandyAndy]

I think you may be able to blame the LPG.
The quality varies wildly between tanker loads and suppliers.
Deb is finding LPG consumption is varying greately between tanks doing the same driving and trips.
She is getting around 220ks/65L,4.6 with stage2 cam,wolf management and auto.
My old Ser3van with a 202/LPG also varied hugely.
ALWAYS buy your gas as early as possible in the morning,the gas in liquid form varies greatly by vol/temp,the pumps are calibrated to read correct in the heat of the day,you can get 10 to 12% extra for free by filling early in the morning.
This will also go towards explaining the varying gas usage.In the heat of the day your gas isnt as ecenomical as in cold weather.
Andrew

[Michael2]

Along the lines of what Landyandy said. I find that I get better economy in the country, but that's not just to do with driving.

If I refuel in Melbourne and do 200km of freeway driving, out and back to Melb, I get slightly better economy than around town.

average town economy 3.5 EFI RR varies from 22-28 litres per 100.

If I go for a long country drive, sitting at similar speeds, my economy gets to 14 litres per 100km!!!!!!

I think it's the Propane / Butane mix that gets delivered to the servo that affects it. In the country, they need pure propane for Gas BBQ cylinders and it's not worth sending another truck out to dilute the gas with cheaper less potent Butane. In town, it's worth their while to dilute it to make some extra cents per litre.

I think Supagas in a couple of their outlets sell 100% Vehicular Propane.

[Michael2]

I had the RR tuned recently. They made the economy worse, and after the 4th attempt told me they needed to fit a 'vaccuum economiser' that leans as the mixture as the timing advances.

I've only done a couple of hundred k's since, it's a bit better (from 37 litres per 100 after they mucked it up to 27 litres per hundered on the first 200kms), but time will tell. I can't see why I got such good economy before, without the 'economiser,' exceptit that I had a vaccuum leak .

[blitz]

best bet is to shove an O2 sensor up her umm in the exhaust to see what it's level of tune is. I found that the best way to get the tune/economy working best.

Cheers Blythe