[Mk2] [Turbo] Hideous Fuel Consumption

[mikey2]

Wondering if anyone can shed any light on my seriously crap fuel economy.
The last day or so, i have put 15 quid in, its nearly on empty now and i have done 35 miles, and not 35 stupid miles either, i have been quite gentle with it, what with it being wet and all.

The Exhaust manifold is cracked, but not really badly.

Does the coolant temp sensor have anything to do with it, cos i can pull that out completely and the sensor bar is completely bare. Other than taht i cant think of anything else. The spark plugs have been changed in the last couple of months, and it hasnt really covered that many miles, as i went to egypt for 9 weeks and before that i was using the scooby, so its only really had about 8 weeks use in the last six months.
Thanks

[karammander]

it could be a couple of things.

your o2 sensor is faulty,

the crack pulling in oxygen and messing up the o2's reading,

the green ecu temp sensor making the car overfuel,

boost leak?

cheers karam

[mikey2]

Ah the green temp sensor, thats the one thats ever so slightly knackered, it doesnt stay in the block properly, the actual sensor has parted company from the bolt part, so thats what would cause an over fuel??? As far as i know the Lambda is fine, and there is no leak in the inlet side of the engine.

[C50]

mine did a lot less than that.. it turned out to be an oxy sensor. Do a self diagnostics test to confirm

[mikey2]

I have ordered a coolant temp sensor, as its hanging out, not even attached the bolt its usually part of!!!! 40 quid from toyota, hope it solves the issue!!!
The last time i checked for codes, which wasnt long ago, the only one that came up was the knock sensor, whicih i sorted, and it throws up occasiobnally, but the lambda hasnt been an issue so far.

[Dean_82]

mine did a lot less than that.. it turned out to be an oxy sensor. Do a self diagnostics test to confirm

How do you do that dude#?

[teazer82sr]

wheres the best place to get the green temp sensor as i am going to try this. im also getting ridicolus fuel comsumption.

[mikey2]

I got mine from toyota, its 40 quid though, but if it solves the issue then it will pay for itself in a couple of tanks!

[mikey2]

To check for error codes, in the engine bay there is a small grey box on the back wall drivers side, has diagnosic written on it. Bridge the te1 and e1 contacts with a paper clip and turn the ignition on. The Ecu light will flash continuously for no codes, or it will flash the code, long flashes then short ones, ie code 52, which i beleive is the knock sensor would be ----- ..
So five long flashes, then 2 short ones, keep an eye out though, after the pause it will flash the next code if there is one.

[Moo]

wheres the best place to get the green temp sensor as i am going to try this. im also getting ridicolus fuel comsumption.

Is your's a turbo? £15 from Camskill

http://www.camskill.co.uk/products.php? ... 5s605p4331

http://www.camskill.co.uk/brand.php

[mikey2]

b0ll0cks

[mikey2]

yeah thats the one, but i don think its made a huge diference to be honest.

[luthor1]

AFM is likely, or a boost leak.

Sticking brakes too, or low tyre pressure. Drive at high speed, then touch each wheel (not caliper or disc!!) and a hotter-than-the-others one indicates sticking pistons/slide pins.

[mikey2]

Well, i can honestly say i really dont think it made much difference to fuel, but it does seem to be smoother now, might just be wishful thinking tho. Car passed emissions so cant have been too bad.

[luthor1]

either the cars being slowed by drag, or it's putting in more fuel than it needs. The latter is tyres/brakes. The former is boost leaks, afm, CTS etc...

[teazer82sr]

wel ive just picked up my sensor from a local auto store for 10 quid. its exactly the same. hopefully it fixes the problem. im not getting any fault codes but the car is using a full tank to 190 miles. and thats not driving hard. i have a few mods tt hybrid ct26 ross pistons 205cc setup walbro fuel pump baileys atmos dv but im running standard ecu fuelling at 1 bar. i was thinking its time for a link ecu maby any ideas?? can the oxy sensor start to break down and give the wrong readings?? without showing a fault code?

[luthor1]

On a rev1 and 2 the atmospheric dump valve will cause over fuelling

[mikey2]

ah yes i forgot about that, good point, i dont have a recirc and on a ct20 i dont want to not have a dv. Oh well.

[teazer82sr]

On a rev1 and 2 the atmospheric dump valve will cause over fuelling

i have heard this before, but as my dv is mounted on the top of my st205cc im not sure if this could be changed. will it cause overfuelling all the time or is it just when the dv opens it sucks the afm flap to maximum causing overfuelling when i lift off the throttle? this is just a guess by me lol.

ive fitted my sensor but havent yet drove it far so im not too sure if its changed anything. i will let u guys know

[luthor1]

You've kinda misunderstood what's causing the over fuelling...

Imagine your AFM measures 1 litre of air passing through it. It knows to add 1ml of fuel to it to be efficient. Then suddenly, between gear changes, you dump out 100ml of air, suddenly the ECU is sill putting in 1ml of fuel, when it only NOW needs 0.7, hence over-fuelling.

Each ad every time you come off the throttle and activate the DV you'll lose air that's been weighed and measured and accounted for, then it'll fuel too much.