Technical bad fuel economy punto

[mzhussein]

ok, mk1 punto 60s team, getting 150 miles to half a tank of city stop-start driving. is this bad? also idle is at 2k when i start car, and drops to 900 after 10 mins. i decided to see if it was the lambda sensor, i unplugged it whilst running, and nothing happened. no chnage that i could tell.
does this sound like i need a new lambda sensor?
have checked idle control valve and nice and shine and clean.
any replises much appriciated.
thanks

 

[5abr3]

I get about 420 miles to the tank regardless of how I drive, I aren't quite sure how that works but there isn't much stop start involved there. Obviously the longer your stationary the more fuel you burn for no miles.

 

[mzhussein]

yeh so definatley somehting wrong lol. not much stationary idling, i tend to avoid traffic, more traffic lights and give way lines.....
so what should i look at to point the blame??

 

[5abr3]

Well if your constantly going between idle and 2k rpm then stopping that will make quite a mess of the economy, what have you checked (include things like tyre pressures, air filter, oil filter etc)

 

[mzhussein]

well, tyres are new, pressure is good, just had new exhaust, check ICV, did a full service about 800 miles ago, and a new HG 500 Miles ago. and ive unpluged and re-plugged the lambda to see if i could make out any running difference...
next port of call?

 

[5abr3]

What speed does the engine idle at? should be roughly 800-900 rpm but I know of one or two that like 1200-1300. Driving style may be a factor but it's unlikely.

 

[mzhussein]

on startting when engine is cold it will go to 2k, then drop to 1500, then after bout 10 mins it will have stabilised at 900ish

 

[5abr3]

That's normal, have you tried seeing what the fuel economy is like on a more free flowing environment like dual carriage ways that are moving at 50+?

 

[mzhussein]

oh ok thats good ....not realy...havnt had the chance to do any longish distance...just my mate who has same car, but in silver, gets easily more mpg than me, and he does the same kind of driving (if more rev happy).

 

[5abr3]

Might be a subtle difference like oil values or something? When you say full service did you flush the coolant system out?

I spend most of my time on dual carriage ways and fairly free flowing roads from 30 to 60 (mixed terrain too) and luckily not much time in jams!

 

[lancianut]

What speed does the engine idle at? should be roughly 800-900 rpm but I know of one or two that like 1200-1300. Driving style may be a factor but it's unlikely.

does it have a cold start valve ,if so give it a good clean,clean the throttle body out to once you done that give it a good hard drive up the road to clean her out my sporting hates being in town for long periods but once you put your foot down she is fine .

i no its not the same engine but i get around town about 180mile on half a tank ,long drive 200 to 230 miles on half

 

[5abr3]

To be honest I aren't sure without going out and looking, I'm way too tired for both memory and that! I'l try and look tomorrow if I remember unless the OP looks first

 

[mzhussein]

does it have a cold start valve ,if so give it a good clean,clean the throttle body out to once you done that give it a good hard drive up the road to clean her out my sporting hates being in town for long periods but once you put your foot down she is fine .

i no its not the same engine but i get around town about 180mile on half a tank ,long drive 200 to 230 miles on half

im on 180 miles and im thru 3/4 a tank!!

how do i clean throttle body...never figured that one, just sort of dabbed it with kitchen towel....

 

[mzhussein]

ok, dont wanna be sending people out now, its freezin were i am lol
just annoyin cos petrol buring a hole in wallet...
thanks so far tho.

 

[5abr3]

It's not the cold, it's the fact I'm half asleep and just off to bed!

 

[mzhussein]

lol, wouldnt wanna deter u from that, sleep is life elixer!
thanks peeps

 

[5abr3]

Specially when you have to be up at 6:30

nite, hopefully have some answers mid afternoon!

 

[Tris Harris]

Just out of interest, have you tried working out your mpg?

how many litres is half a tank?

brim it, use the tank, and then fill up again- record how many litres it takes to brim the car again, and then divide this by 4.5 to get gallons and then divide the total amount of miles by this number.

This will give a better indication of if your getting good or bad mpg or not.

I take it tyre pressures are right and its been serviced recently?

 

[mzhussein]

well, i recently brimmed it, and reset trip counter, so i could go brim it again and check actual mpg, btw a full tank is 50L ish. im getting roughly 23mpg goin on rough calculations. but ima go brim it now and measure more accuratley.

edit: yes been serivced recently and tyres are good.

 

[Tris Harris]

well, i recently brimmed it, and reset trip counter, so i could go brim it again and check actual mpg, btw a full tank is 50L ish. im getting roughly 23mpg goin on rough calculations. but ima go brim it now and measure more accuratley.

edit: yes been serivced recently and tyres are good.

oh right, i never got near 50 litres in mine, usually nearer to 43/44- even though the tank is supposed to be 50ish litres