3sge gen3 running rich

[~SlideWays~]

I recently bought a '94 Curren as a daily driver, I was pleasantly surprised how well it went and handled.

So I put a full set of Bridgestone Adrenalines on it and took it for a trash up the Rimutaka's, it used a decent amount of fuel as you'd expect.

But the last 2 tanks I've nana'd it to see what the fuel consumption was like. Granted 5 days a week I'm stuck in traffic but it consistently seems to be doing 9km/l.

I was thinking maybe a new oxygen sensor would solve the problem, then I googled it and found a suggestion to replace the engine temp sensor.

Before I go spending money, can anyone confirm what sort of km/l a 3sge would do with town driving? Pretty sure it'll be a Gen3 btw.


Cheers

[sergei]

First of, before randomly replacing sensors check the VF output in diag. connector (multimeter in 20V range).
If the output is 2.5V then everything is OK and most likely you have heavy foot or not measuring right.
The 3SGE should take around 10L/100km with average driving around town.
First thing I would blame stuck thermostat.

Now back to VF, it is a very useful output - it basically shows how much ECU is compensating from base fuel map:
0V it thinks it is running very lean, so it dumps fuel, and/or it is in the open loop mode
1.25V it thinks it is running lean, so it adds a bit more fuel
2.5V no deviation from base fuel map
3.75V it thinks it is running rich and reduces a bit of fuel
5V it thinks it is running very rich and reduces a fair bit of fuel

If your VF is in 0V range, check your OX1 output, if that is fluctuating between 0V and 1V (need to set multimeter to 2V range), then your oxygen sensor is OK, and something else is stuffed (open thermostat, or WTS is out of spec.)
If it is not fluctuating, your OX sensor is either stuffed or clogged. To check it remove the OX sensor, place it in such way so you can have multimeter hooked up and ability to heat it up with butane torch to red hot (the working end of course). Multimeter should be set in 2V mode and connected to white and blue wire (or gray wires), basically the wires which are not heater wires.
Once you start heating the OX sensor, if sensor is OK it should read 1V while you apply gas flame on to it.

[~SlideWays~]

First of, before randomly replacing sensors check the VF output in diag. connector (multimeter in 20V range).
If the output is 2.5V then everything is OK and most likely you have heavy foot or not measuring right.
The 3SGE should take around 10L/100km with average driving around town.
First thing I would blame stuck thermostat.

Now back to VF, it is a very useful output - it basically shows how much ECU is compensating from base fuel map:
0V it thinks it is running very lean, so it dumps fuel, and/or it is in the open loop mode
1.25V it thinks it is running lean, so it adds a bit more fuel
2.5V no deviation from base fuel map
3.75V it thinks it is running rich and reduces a bit of fuel
5V it thinks it is running very rich and reduces a fair bit of fuel

If your VF is in 0V range, check your OX1 output, if that is fluctuating between 0V and 1V (need to set multimeter to 2V range), then your oxygen sensor is OK, and something else is stuffed (open thermostat, or WTS is out of spec.)
If it is not fluctuating, your OX sensor is either stuffed or clogged. To check it remove the OX sensor, place it in such way so you can have multimeter hooked up and ability to heat it up with butane torch to red hot (the working end of course). Multimeter should be set in 2V mode and connected to white and blue wire (or gray wires), basically the wires which are not heater wires.
Once you start heating the OX sensor, if sensor is OK it should read 1V while you apply gas flame on to it.

Great post Sergei, I'll see what I find tonight. Cheers

[~SlideWays~]

Hmmm interesting.

VF1 is reading less than 0.1v while cold and no different after a drive.

OX1 after a drive to warm up sensor and idling for a few minutes is between 0.01 and 0.20.

So from that I can assume the o2 sensor is OK.

It gets up to temperature very quickly and doesn't budge from middle of temp gauge so I can assume the thermostat is OK too.

So the VF1 reading would explain it using more fuel than expected.

Does a 3sge have just the one water temp sensor or one for the gauge and one for ECU?

[~SlideWays~]

...or not measuring right.

Filled to top, reset trip meter, driven for a week and filled at same station. Divide total fill litres by trip meter km's.

Did that two weeks in a row and get consistent 9km/l.

[sergei]

...or not measuring right.

Filled to top, reset trip meter, driven for a week and filled at same station. Divide total fill litres by trip meter km's.

Did that two weeks in a row and get consistent 9km/l.

good , what is the temperature like and does it go down on highway?

[~SlideWays~]

...or not measuring right.

Filled to top, reset trip meter, driven for a week and filled at same station. Divide total fill litres by trip meter km's.

Did that two weeks in a row and get consistent 9km/l.

good , what is the temperature like and does it go down on highway?

Not sure if you saw my other post but its consistent temp bang on the middle of gauge and gets up to temp quickly.

It does idle a bit high at operating temp too around 1100 to 1200rpm which i noticed Tues and Wednesday, today the headlights/wipers/heater are all on so its about 800rpm because of load on alternator.

Could possibly point to Water temp sensor?

[sergei]

...or not measuring right.

Filled to top, reset trip meter, driven for a week and filled at same station. Divide total fill litres by trip meter km's.

Did that two weeks in a row and get consistent 9km/l.

good , what is the temperature like and does it go down on highway?

Not sure if you saw my other post but its consistent temp bang on the middle of gauge and gets up to temp quickly.

It does idle a bit high at operating temp too around 1100 to 1200rpm which i noticed Tues and Wednesday, today the headlights/wipers/heater are all on so its about 800rpm because of load on alternator.

Could possibly point to Water temp sensor?

It is difficult to say until you test the WTS. You can test it with a household thermometer and ohm meter and some hot water.
Here is the info on how to do it (at the end of the article):
http://www.autoshop101.com/forms/h32.pdf