Bad Fuel Economy

[scutch0]

ok guys,

ihave just fitted a 12,000 mile 4efe im my starly as my old one had just about had it.

before i fitted it i had REALLY bad economy... dunno mpg but i was spending about £60 a week on just doing about 15 miles a day....

now the new engine is in its better on fuel, but not by much. it still drinks the stuff.

i had an accident in it about 2 years ago, and its been bad ever since, and my local garage have given it a check over and cant spot anything obvious...

do you guys have any ideas or experiences on what i should do or check??

by the way, i have given the new engine a 500 mile run in, and that means not taking it over 3000rpm... so its not me driving with a heavy foot!!

i have just a back box fitted.

and it passed mot with flying colours a few months ago when the economy was really bad.

Rich.

[Richie (Paseo)]

What kind of oil are you using? I used to use cheap oil and found that I wasnt gettin many miles to the gallon, So I got some engine flush, flushed all the old oil out, put fully synthetic oil in and some extra slip oil additive and that increased fuel consuption hell of a lot!!!

Maybe worth a try?

Rich

[nrgizerbunny]

check the temp sensor

[toyotasera.co.uk]

also check thermostat.

There are a number of sensors which could be confusing the ECU and making it run rich.

You don't have one of those "cheap power mods" you see on eBay fitted?

I wouldn't bother with oil slip additive, waste of money and do more harm than good.

[nrgizerbunny]

I thought the thermostat was independent of the ECU but I may be wrong!?!

[scutch0]

cheers for the imput guys...

im using some high grade 10w 40 cougar oil.

You don't have one of those "cheap power mods" you see on Ebay fitted?

no i dont have one of those things fitted.

and im a bit confused by what u guys are saying... ive just fitted a totally new engine... so surely i should have noticed the difference?? or is there a temp sensor off the engine i should check?

could it be the ecu?

Rich.

[TheNissanMan]

check exhaust is all connnected, no blowing bits (had mine fixed last week and a load better)...

check O2 sensor, if dodgy car will run exceptionally rich and v heavy on fuel....

[toyotasera.co.uk]

the thermostats on these engines tend to fail open, which is good for safety as it prevents overheating, but it means the car takes ages to get up to temperature, and the water temperature sensors in the thermostat housing keep the car on the artificially rich cold start mode for longer.

Also if they have an automatic gearbox which have an extra sensor which keeps the gearbox out of the overdrive gear until its trigger point is reached, then the car is not running in the most economic gear.

Changing the thermostat improves mpg in two ways - allowing the car to run more efficiently and using a more suitable gear.

[riko666]

hmm, not to steal your thunder, i just got 320mi on a full tank, and i struggled to get 240mi on a tank before hand...im well chuffed

[cynos_boy]

Iam only getting around 320-350 per tank and I only have a 1.3- with no engine mods-that I know of-

but perhaps that it's just the fact that every time i hit a bit of motorway (8) my speedo keeps reading 180+kmh, must be faulty , your honour!!!