Really bad fuel economy problem

[EREXON]

Yeah I know that it has detected that one side (bank) has significatly different air/fuel mixtures. To have different readings on either side. The air coming in is the same for both banks? the temp sensor is the same for both banks?

The only thing that could be stuffed on one bank only could be an injector.

Might throw a bottle of injector cleaner through it and see if it clears it out or makes it worse. if so then i know its the injectors.

 

[EREXON]

A CO2 sensor senses oxygen right? so theres too much oxygen passing that side sensor so it thinks its running lean and richens the mixture (viscious cycle). its not programmed to sense too much fuel just oxygen. you need to work out where that oxygen is coming from. maybe a vacuum/air leak via a loose inlet manifold perhaps. dont quote me on it though im just guessing.

It reads how much oxygen is left in the mix therefore knowing how much wasnt burnt off and increases the fuel to burn up all the oxygen. If the fuel injectors are stuffed they wont be injecting right and therefore that could stuff up the air/fuel mixtures.

 

[88GreenVN]

Might throw a bottle of injector cleaner through it and see if it clears it out or makes it worse. if so then i know its the injectors.

When was the last time you put cleaner in the tank?

Also has the car always been bad on fuel? Or is it that over the years just used more and more?

 

[ephect]

it'll be the grounding issue for the o2 sensors thats causing the variation between banks code. i have seen it a few times, and this was the fix, with new o2 sensors

yes its a good idea to put thru some injector cleaner too on a few tanks of fuel.

 

[Surfwagon]

it'll be the grounding issue for the o2 sensors thats causing the variation between banks code. i have seen it a few times, and this was the fix, with new o2 sensors

Has anyone actually done this and had their fuel economy return to normal.
So far from all my reading no one has actually said the earth or cut the pink fixes have cured their fuel guzzling.
My cut the pink fix has made it better but still worse than it used to be.
Also similar thread.
https://forums.justcommodores.com.au/threads/earthing-off-your-ecotec-o2-sensors-2.82899

SW

 

[EREXON]

Ok guys just an update.

Got:
- injector cleaner
- coolant (since i was getting dirty)

I started by cleaning up the earthing points for 02 sensors (not cut just clean) and put in a thicker earthing cable on the -'ive terminal and cleaned it aswell at the contact point on the body.

Then i flushed the coolant and heater core and topped it up with fresh coolant. And threw in some injector cleaner.

Once all was done i started the car to bleed the coolant all seemed good.
Then it began to sputter really bad (misfiring).

Got the air compressor and aired out all eletrical to make sure no water was anywhere and checked the leads to make sure nothing was wet from coolant flush.

Still the same so i just assumed it would be the injector cleaner so i just kept revving it and took it on a good throttle opener and giving it heaps of gas.

As predicted the engine smoothed out and started running good again.

went to the servo topped up with premium, reset the ecu again, and went for a 10min smooth drive.

The trip computer has gone the lowest i have ever seen it at 15L/100Km.

Hopefully it starts to drop lower and lower.

IM GUESSING THE INJECTORS WERE CLOGGED UP BAD AND THE CLEANER HAS FLUSHED IT PRETTY GOOD.

I will throw some more injector cleaner just to make sure it cleans everything up well.

if it shows improvements then i know the injectors are at fault.

fingers crossed my fuel economy will start to smoothen up.

 

[pjdm1980]

My statsman was using heaps of fuel and the mechanic found an emission hose was off.

 

[EREXON]

Its really wierd after the injector cleaner it went to 15 now back to 20L/100km

dont get this car

would it be the injectors?

 

[danja]

Just checking, are you driving a few hundred km to get these readings, do you do the maths when you fill up at the pump? It takes a fair bit of distance for in-car meters to read accurately. Even after a full tank mine is still often a litre or so off, and if I've only driven 10-20km it can be up to 10L off!

Edit:

Also, I've heard people say that injector cleaner can "dislodge" crap which has been stuck in the fuel system and that can actually cause more blockage in the injectors. If it were me, I'd run a few tanks of premium, which has detergents in it already.

Have you done spark plugs recently? If it's been running rich for ages they are likely to be fouled. Pull some out (from each bank) and have a look, compare them to these:
http://www.ngksparkplugs.com/techinfo/spark_plugs/faq/faqread2.asp

Rich mixture will cause them to look more like the second image.

 

[alex2_s]

My statsman was using heaps of fuel and the mechanic found an emission hose was off.

as in a vacuum hose?