Really bad fuel economy problem
THIS IS MY FIRST POST
So FIRSTLY HEY TO ALL
I have used this site previously however never had to really ask my own questions. At least know i can offer my 2 cents.
Well onto the problem:
I have a VS Calais series II.
With really bad fuel issues. It bearly reaches 330KM on full tank. and seems to be running rich.
I have put plugs and new leads in about 5000Km ago as the problem has been on going for a while now.
Iv read other posts, and a few pointed me into the direction of the 02 Sensors.
I firstly pulled the codes, which nothing came up apart from 12 --- all ok
So i then removed the 02 sensors just to have a look and see what is happening before i get some new ones.
Well this seemed really odd to me.
the drivers side sensor was black and covered in carbon build up. The passanger side was white like snow??????
Can anyone suggest anything else or if the 02 sensors seem odd
THANX IN ADVANCE
Almost not here!
The o2 sensors tell the ECU how much fuel/air to give the engine.
If they are not working correctly - car can use heaps of petrol. Sounds like 1 of yours is kuput!
Hi,
Thanx for the reply.
I know what the 02 sensors do , but i just cant understand how 1 side is black with carbon and the other is white. I would expect both to be covered in black sh*t as its running rich.
Is it that 1 side is running rich and the other fine due to possibly the 02 earthing issue???
shouldnt the 02 sensors be a creamy colour why is one black with build up and one pure white.
Almost not here!
Maybe you could try swapping the o2's over see if they swap colour. If the white one goes black then you could look at the wiring a bit closer for that side.Originally Posted by EREXON
Just found a little info on the tip of an 02 sensor and how to diagnose whats going on.
The tip should be clean and gray.
If it's very black and sooty, you've been running rich. This can become a vicious cycle with the ECU, engine and O2 sensor. The O2 sensor gets a little sooty from running rich and causes the output of the sensor to drop so the ECU makes the engine even richer causing more soot to build up on the sensor.
If the sensor tip is white looking you have probably used silicone somewhere that is not sensor safe and the sensor has been poisoned. You can test it to be sure but silicone will kill an O2 sensor pretty quick. I think it's the acidic acid that does them in but I'm not sure on that.
If the sensor tip looks red, maybe someone has been using leaded race gas and has probably killed the O2 sensor by doing so.
If the sensor has whitish looking scale deposits all over it, look for a water leak such as a bad head gasket or something of that sort. The sensor is probably toast in that case from contamination from the antifreeze in the coolant.
SO I THINK I HAVE A FAILED RIGHT SENSOR due to silicon, some smart mechanic used the incorrect sealer somewhere along the way.
As for the right side (drivers) thats very rich.
Now i can change the sensors but how do i know this wont happen again???
Why was i running rich and will the next sensor die from silicon poisoning aswell
One problem that affects the O2 sensor operation is contamination or poisoning by silicone, this shows up as a fine white powder on the tip of the sensor and will reduce the voltage output of the sensor when the mixture is rich, and this will cause a loss of fuel economy and increased CO and HC emissions.
So im thinking the left 02 sensor(white tip) failed due to silicon poisoning which then increased the fuel mixture which then would have fouled the good (right) sensor...
Does this make sense to anyone???
Almost not here!
How dose the o2 sensor get covered in silicon? - like get into the system to end up on the sensor.
Almost not here!
Also can you clean them up a bit? May be worth a try before you go putting new ones in.
But then again new sensors should help the economy from the next tank and if not put the old sensors back in and keep looking for the problem.
Do VS V6's still run both coolant sensors?
If so try a new ecu one
shouldnt the computer register a code if the sensor is faulty?
Doesn't drive like this
If one of the injectors in one side had a bad spray pattern, or leaking - won't that cause one side to be covered in soot?
Swerves for gay koalas
Mind Me Bloody Beer Champion!
Just checking this is an Ecotec right?
The air-fuel ration of each side (bank) of the engine is is varied independently, so if the O2 sensors say one side is running lean, the ECU will increase the duty cycle of the injectors on that side only, which as you mentioned in a later post can be a vicious cycle if the reading was poor to start with.
They have to get REALLY shafted before the computer will throw codes, they can be pretty bad and not show up on the dash.
Thanx for the replies.
Iv read that they may have to be really gone to throw a CEL.
There has also been cases where a self code check shows everything is ok however a diagnostic scan tool shows problems.
This is my first step to try solve this bad fuel problem.
I think since the 02 sensors look horrible its worth a shot.
I will change them over and reset the ecu and see what happens.
i'll let you guys know if anything changes.
once again keep the replies coming anything is a big help right now so thanx.
Also if i have a leaking fuel injector how would i check that? Iv got the cover off and everything looks snug when the cars running i dont notice anything wierd from the injectors?
can i do anything to verify they're not leaking????
Its in the fumes as they pass through the exhaust. I read this up on a few sites. That a white powdery deposit is caused by the wrong type of sealant used and the silicone is bad on the 02 sensor, hence most write 02 sensor safe on the packet.
yeh a apparently the vinegar like substance in the sealant is teh thing that kills teh O2 sensors thats why allot of people recommended ultra blue or teh like on fuel injected cars
do you guys think if i go ahead and change the 02 sensors they will be all good.
Coz i tried cleaning them, compressed air and carby cleaner, put them back in but i think its gone even worse now.
It shows 35L / 100KM **shocked**
the funy thing is NO CEL (check engine light) YET!
This thing loves juice.
BensVR
yea got same prob maybe we should by a new commodore or somethin spent 3000 tryin 2 fix the problem sik of it now anywayz
Swerves for gay koalas
Mind Me Bloody Beer Champion!
35L? You could drive a Ferrari with better economy than that!
The carby cleaner might have killed them, I'd get some eBay sensors (there's pretty much one guy selling them on there, I've used him before he had good quality sensors then with OEM plugs, about half the price of Holden ones). About $120 for the pair. Given how much fuel you're using they should pay for themselves in about 5 minutes! lol
Donating Member
if you have one leaking injector the only real way to check is to rip em out and take em to get checked & cleaned, and replace if necessary.
the other way u'll eventually find out is it will end up loggin 'variation between left and right banks'. which normally points to o2 sensors, but if there new and working fine, then it'll end up being injectors to which you would feel it in loss of performance, sluggish and possibly running rough.
Buy a set, and change your o2 sensors first, no good cleaning the old ones that are over 100000kms old, they'd be buggered anyway. this should get things rolling.
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While it could be one of the O2 sensors or their associated wiring circuit, here's a couple of other things to check:
Coolant will also contaminate O2 sensors.
An exhaust leak (like an exhaust manifold gasket) upstream of an O2 sensor can give a false lean output.
A leaking inlet manifold gasket can likewise run lean.
An ignition system fault will show on an O2 sensor as lean and skew the fuel mixtures rich with ECU mixture self correction.
No they never do. Mines not working at the moment, it does work but it's reading almost 40c lower than it should and inconsistant, it's costing me like 100ks per tankso I have to get onto that
HEY GUYS JUST AN UPDATE.
WENT AND GOT 2 x 02 sensors, everyone wanted from $80 - $100 ended up finding them from a mate who has an account with a parts shop for $66 each.
Bought 2 they are NGK and look pretty nice lol
So i removed the old ones popped the new ones in and dropped the oil and filter whilst i was at it.
With the old sensors trip computer going to and back from parts shop was on 25L/100km.
after installed and ecu reset and a quick 10min drive the trip computer is currently showing 18.3L/100Km.
Also things noted:
- shaking problem dramatically reduced / gone. Car use to have the small shakes at idle and now seems nice and smooth.
Engine whilst idling sounds happy and smooth a bit of a shake problem before hand.
- Car seems to be running alot nicer smooth gear changes etc...
- Wiped the rear bar from black deposits and after the drive not one spot of black sh*t on rear bumper.
Dunno if its in my head but it seems like te car is running alot better.
I will keep track of how it goes as it is pretty much full tank at the moment.
So hopefully i would be hoping to see 15L/100Km ---- THAT WOULD BE SOOOO NICE
thanx all for the help and tips i hope this has solved the problem.
I will let everyone know how it goes that way if some1 else has same issues perhaps it can help them.
THANX ALL
hey, im just asking.... what abt aftermarket extractor as i run on pacemaker extractor .. and there have one o2 sensor but it not two sensor as my car is vr commodore v6 .. im soo confused with it .. as i think my o2 running rich as i can smell from this as come out of exhuast thanks cheers
there is no guarantee that the 02 sensor will fix any car running too rich.
I was willing to change them anyway as the car has almost done 200K.
if it does fix the problem i'll be very happy if not it could be many other things.
ALSO JUST A QUESTION.
can a car be tuned although standard ECU?
i know to change the mixtures you need an ecu or a piggyback system however can a standard car need a re tune?
haha well i might change mine for good measures...only 25 bucks but ay better then $109 from holdenNo they never do. Mines not working at the moment, it does work but it's reading almost 40c lower than it should and inconsistant, it's costing me like 100ks per tank
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