View Full Version : Causes of poor fuel economy
I can think of a few things as to why, but I want to hear from you guys so I can check possible causes off the list that I may not have thought of.
270 miles to a full tank is not good and I think a bit of investigation is in order! I will be replacing spark plugs, and may replace a fuel line in the near future just in case it's that...any other thoughts?
Cheers!
busterhymes
28-10-2009, 09:57
injectors ?? :)
lambda is a common one, or coolant temp sensor, or sticking cold start injector
Poor ignition through bad HT leads or anything on that side of things. TPS did it for me. Blocked fuel filter.
hole in the fuel tank :idea:
:D
16v_paddy
28-10-2009, 11:04
I get about 300 miles to a tank if I'm taking it steady
ive emptied mine in 130 miles before. all at 70 of course. hehe
Mine has terrible fuel economy also, most things were replaced at last service, new HT leads, spark plugs, air filter cleaned etc. seemed to make no difference. I put it down to the fact it's tuned and I have a lead foot lol! It's not an every day car so doesn't bother me too much
also check air temp sensor as it plays a part in fueling :roll:
340 odd miles in the renault 9 with a full tank :D
probably get more if i were driving like an oap
Hmm, lots to consider then! I did guess most of these. I was considering having my injectors sorted out as I would guess they have never been cleaned, and fitting new spark plugs.
Lambda has also occurred to me but I have avoided messing with it as they are a BITCH to get off after years of rust! Maybe a nice job for the garage :D
TPS is a cause? Hmm, weird. Air temp sensor could be one I guess. 5th Injector was also on my mind but I think I would be able to tell when driving (be like having the choke out even when warm!)
The HT leads are super duper magnecors, quite new, CTS is brand new as well, wiring is fine I think.
No obvious leaks. I fixed a aux tank leak and replaced all fuel lines.
As I understand it, the TPS measures the throttle air valve position, it is part of a system which signals for a measured amount of fuel depending on valve position and other factors like engine load. If the actual/measured positions are not the same it can change the air/fuel mixture and cause overfueling. (mine was permanently running rich) and underfueling, poor performance. After renewing I gained an average 40miles a tank. 300 to 340.
Had yours ever been tampered with though kenny? Don't think mine has. Did you buy a new one?
I did buy a new one. It started running roughly, which was one ht lead breaking down, but even after replacement the car was still not right. Like you I done all the normal things untill I ended up at a specialist with diagnostics, tps was diagnosed as faulty.
Hey Wobba, i understand your plight! I tested my W3 the other day as im forever watching the gauge go down, and was getting about 23 mpg.
Regards mods it has a lightened fly, breathing mods (filter, exhaust) and gunner chip 180. Surely they should return more than this? Ok, i wasn't exactly driving ultra economically, and gave it some full revs action, but surely 23 is v8 territory!! :shock:
Since mine has been played with a bit i get n average about 130miles per full tank around town and about 225/230 on a m-way run :roll:
130 miles a tank, :shock: I'v got a 6.5ton yank truck that does better than that, what sort of 'playing' have you done? I get 340+ without trying from my williams 2, Other than the time I described earlier I have always got 300+ without trying
sideways danny
31-10-2009, 16:38
Since mine has been played with a bit i get n average about 130miles per full tank around town and about 225/230 on a m-way run :roll:
jesus christ. I'm getting 300 miles to a tank, and it's heading towards 190bhp (184 before the willy manifold and non shit exhaust)
That's TERRIBLE. there's no good reson for you to have it that bad
sideways danny
31-10-2009, 16:39
the 260bhp supercharged 172 does better than that FFS
Tell me about it,its one of the reasons the cars being stripped and sold next year,i cant afford to keep running it :cry:
sideways danny
01-11-2009, 15:26
get it mapped properly
theres something wrong there mate, dont kill the car for that, get it sorted properly, as said its probably a shite map on it
i have no idea what i get really, dont keep track but got to dover from doncaster on 30 quid, about 240 miles cruising at a steady 80 odd. but if i boot it it gets to the low teens mpg or below :shock:
white16valver
03-12-2009, 13:49
Had yours ever been tampered with though kenny? Don't think mine has. Did you buy a new one?
Hey Wobba :)
Did you change the TPS?
Was it £££?
I'm thinking that I might need to do mine - it always seems to run rich (you get that white 'steam' from the exhaust even when it's quite warm :shock: ) and I struggle to get 300 miles out of a tank!
white16valver
08-12-2009, 11:53
Bump for a reply from the wobba ;) :P
Am I the only person that thinks 270 miles from a full tank isn't that bad? It's roughly 30MPG...
Had yours ever been tampered with though kenny? Don't think mine has. Did you buy a new one?
Hey Wobba :)
Did you change the TPS?
Was it £££?
I'm thinking that I might need to do mine - it always seems to run rich (you get that white 'steam' from the exhaust even when it's quite warm :shock: ) and I struggle to get 300 miles out of a tank!
No but I am thinking about it, I think there is an uprated one you can get or one from a different model...
LEIGH-ANNE
08-12-2009, 12:58
Im gona put in a full tank to see how much i get today... I usually just put £35 in
Would be good to see how mine compares tbh
white16valver
08-12-2009, 13:46
Had yours ever been tampered with though kenny? Don't think mine has. Did you buy a new one?
Hey Wobba :)
Did you change the TPS?
Was it £££?
I'm thinking that I might need to do mine - it always seems to run rich (you get that white 'steam' from the exhaust even when it's quite warm :shock: ) and I struggle to get 300 miles out of a tank!
No but I am thinking about it, I think there is an uprated one you can get or one from a different model...
I'm confused... lol
There's an uprated one? What would be the difference from standard?!
Yea I think there is, well, that's what K-Tec were implying when I was chatting about their ITB kit...
Yea I think there is, well, that's what K-Tec were implying when I was chatting about their ITB kit...
'Hall effect contactless throttle position sensor'
The hall effect just refers to the magnetic rotation, contatless however I don't know about. May not be useable on standard loom...?
sideways danny
08-12-2009, 15:06
had issues with the stock crank sensor lots of times. They've been quite unreliable in the past when used with standalone. That kit includes a better, more reliable sensor. Not for use with the stock ECU though
sideways danny
08-12-2009, 15:08
oh shit mis-read, you meant the TPS.
OK, the contactless TPS is also for use with standalone TBH. It's been sourced to replace the cheap TPS that normally comes in ITB kits which has a short life expectancy.
Not for use with the stock ECU though
Hehe, didn't think so!
I'm still considering ITB's. Wonder if K-Tec still need a donor car...
sideways danny
08-12-2009, 16:11
Call and have a chat With Andy. Was there sunday helping finish off some mapping on an ITB'd F7R
my mpg round town is really terrible (loads of stop/starts etc in london ) but when on the motorway is brilliant as long as i keep it at 70. drove to wales from london last week and filled the tank before i left (55 litres ) keep the car more less at a constant 70mph and drove 203 miles, by the time i got there i had just over half a tank left. was well happy with that :D put an extra £10 in to take it to 3/4 and done the same back home. arrived at piccadilly circus in london and it was sitting just under 1/4 got stuck in traffic for an hour and by the time i got home the red light just started to flash and i live 10mins from piccadilly circus. i love driving and living in london :lol:
That's really good Jay. Got any tips? I should have some newly cleaned injectors and next month a new lambda going in too. Hope it helps!
I get 27 MPG driving like a girl.
I am thinking ITBs may be the way to go to get better economy driving on part throttle everywhere in heavy traffic... :D
top tip of the day : only drive on a clear motorway at a constant 70mph or under, any other type of driving will yield horrific mpg :lol:
btw my mpg is ****in terrible at the sec, getting mapped at rs tuning next week tho so should hopefully improve :D
top tip of the day : only drive on a clear motorway at a constant 70mph or under, any other type of driving will yield horrific mpg :lol:
btw my mpg is F***IN terrible at the sec, getting mapped at rs tuning next week tho so should hopefully improve :D
Yea, I was going to say you need to get mapped up again lol.
white16valver
08-12-2009, 18:30
I am thinking ITBs may be the way to go to get better economy driving on part throttle everywhere in heavy traffic... :D
Any excuse ;)
I am thinking ITBs may be the way to go to get better economy driving on part throttle everywhere in heavy traffic... :D
Any excuse ;)
:winkey:
Well the probable cause for your poor fuel economy is..............................THE FOOOOKIN DIVERS BOOT ON YOUR RIGHT FOOT!!! :shock: :lol: :lol:
did you sort ur fuel economy out wobba, i'm having the same problem, it just doesnt seem to give the same fuel economy as every 1 elses.
i'v brimmed the williams up tonite so i will let u kno how many miles i get from it.
i'v changed the lambda, leads,distributor and arm, plugs and i cleaned the air filter and the throttle body and inlet out aswell. the injectors were cleaned wen martin owned it so i dont think it could be that.
white16valver
15-01-2010, 22:54
Just to check, where is the cold start injector? How would it stick??
I'm thinking that might be what's up with mine lol
Or perhaps new injectors and TPS....
More bloody money!!
MatBrown
16-01-2010, 00:35
Underside of the inlet manifold.
Mat.
did you sort ur fuel economy out wobba, i'm having the same problem, it just doesnt seem to give the same fuel economy as every 1 elses.
i'v brimmed the williams up tonite so i will let u kno how many miles i get from it.
i'v changed the lambda, leads,distributor and arm, plugs and i cleaned the air filter and the throttle body and inlet out aswell. the injectors were cleaned wen martin owned it so i dont think it could be that.
No, not sorted it yet, though I've not really tried hehe, weather has been too poo! It's not THAT bad, I have modded the car a bit afterall I guess.
Lately I've barely driven it fast at all, just when I think I can open her up: traffic jam.
white16valver: the 5th injector bolts onto the underside of the inlet manifold. It's a bit different to the other injectors. Bit pissed at mo so cant really explain hehe. You can get to it with inlet in car, but ideally you want the bonnet off at least and the rad as well preferably.
Getting some injectors off someone and refurbing them is an option and not that expensive tbh. If I get the work I am planning done in the first quarter of this year and I upgrade injectors I'll have 2 spare sets. Got a spare set here but I'm planning on having them tested and cleaned and using them.
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