High Long Term Fuel Trims - why?

[glenhendry]

This is a screen shot of my Torque app after about a 20km drive. As you can see my LTFTs are both up high and are staying there. They have been there for days. I believe that means that fuel is being added to the default fual map, and fuel consumption figures agree.

What I dont know is which sensor is out of true. No fault codes are being thrown. The minimum value on the MAF looks slightly low? I know the O2 sensors are good, and they are staying 0.0-0.8 for a long time, rarely getting to 0.9, which I believe they are supposed to.

If they MAF is reading low, would that result is less fuel injected and then a lean reading on the O2 sensor which causes the high LTFT? The MAF is only a few months old, and is genuine.

Note: she is running very well on all other accounts.

[Keithy P38]

O2 2x1 is reading much higher than the other, is there a reason for it? Your stft on that bank is reflecting such.

I'm not a guru so feel free to put me in line if I have stated something silly!

[glenhendry]

Nah Keithy, the O2s flick from 0.0-0.9 every second or so, and should do. The snapshot in time isnt important on that particular guage. The min and max values over time is important though, for this investigation (I think) :)

[Hoges]

The O2 sensors have a heating element. Perhaps the element of the lower reading one is not operating as it should.

I'd suggest a steady 25km (each way!) run down the nearby freeway and then recheck the numbers. A 20km one-way trip is probably the bare minimum to stabilise the system, even in SEQ balmy weather!:D

You reset the adaptive fuel values to zero with a Nanocom or Faultmate... can you do the same with the Torque app... start the re-learn process?

BTW is the screen shot looks great! is it from your phone or a Tablet?

[glenhendry]

The O2 sensors have a heating element. Perhaps the element of the lower reading one is not operating as it should.

I'd suggest a steady 25km (each way!) run down the nearby freeway and then recheck the numbers. A 20km one-way trip is probably the bare minimum to stabilise the system, even in SEQ balmy weather!:D

You reset the adaptive fuel values to zero with a Nanocom or Faultmate... can you do the same with the Torque app... start the re-learn process?

BTW is the screen shot looks great! is it from your phone or a Tablet?


The O2s heating elements throw codes if it cant pass the ECU tests I believe. The fact that its bas on both banks suggests to me intake air leak or MAF, but the intake is pretty solid, and I am sick of changing MAFs! :)

The LTFTs have been that way for a couple of weeks now, even after 100km trips to Sunny coast and back.

I have reset adaptive values with FaultMate, the LTFTs end up back where they are.

Screen shot is from Torque on android, listening to a Kiwi OBD bluetooth dongle - the Kiwi device is good, but Torque can only reset fault codes, not reset adaptive values.

[benji]

I'm not quite up with O2 sensors and how they operate, so I may be barking up the wrong tree.

Your water temp on the pic being 85 is too cold. I know the GEMS system starts richening the mixture up at 87 to get the motor back to temperature.
Does it heat up to where it should be?

[glenhendry]

Very good question Benji, no, it doesnt. That is the temp that it runs at since putting in a new water pump and radiator last month. It gets up to that temp quickly though, which suggests the thermostat is closing and opening?

I am suspicious about the low value for the MAF. I believe MAFs fail "low" when they fail so can someone please run Torque across an OBD adaptor for a longish trip and tell me what their MAF reads as a low value?

Once I can confirm that low value (I am getting 5-6, and I think from memory it should be 9 or 12) is ok, I will look into that temp suggestion.

[Fitzy2011]

Hi Glen

I have a spare MAF if you want to try it for a while.
Ken

[glenhendry]

Hi Glen
I have a spare MAF if you want to try it for a while.
Ken

Wow, great idea - why didnt I think of that?!

Tell you what, if I can borrow it for a few days, I will commit to recording min and max values for various MAFs under various temp conditions and record them here for posterity. We have a few threads around with voltages, but it will be much easier and more useful in the future with grams/sec over commonly available smartphone technology.

[Fitzy2011]

I,ll call you Thursday and drop it off to you.
Ken

[PhilipA]

Although I appreciate that you want everything to be correct, it doesn't matter too much if the MAF is low reading as the o2 sensors will correct the mixture as they are doing.
The only time it may be a problem is when the sensors are cold and the vehicle is running off the MAF, generally a few minutes after cold start.

Regards Philip A

[glenhendry]

Your water temp on the pic being 85 is too cold. I know the GEMS system starts richening the mixture up at 87 to get the motor back to temperature.
Does it heat up to where it should be?

Thanks for this. The thor thermostat opens at 84, so on a cold day the engine coolant it may not get any warmer than this.

[davidsonsm]

This is a screen shot of my Torque app after about a 20km drive. As you can see my LTFTs are both up high and are staying there. They have been there for days. I believe that means that fuel is being added to the default fual map, and fuel consumption figures agree.

What I dont know is which sensor is out of true. No fault codes are being thrown. The minimum value on the MAF looks slightly low? I know the O2 sensors are good, and they are staying 0.0-0.8 for a long time, rarely getting to 0.9, which I believe they are supposed to.

If they MAF is reading low, would that result is less fuel injected and then a lean reading on the O2 sensor which causes the high LTFT? The MAF is only a few months old, and is genuine.

Note: she is running very well on all other accounts.


Which torque app do you use?

[Cannon]

It's the Android app;

https://play.google.com/store/apps/details?id=org.prowl.torquefree

I use it too & it's great :)

[davidsonsm]

Thanks - just downloaded myself to a new level of geekery. Incredible. Bluetooth DIP II ordered. Just need to learn how not to scare myself interpreting the readings. Or more importantly, when I should take note.

[FANTOM P38]

Purchased the ELM couple of months back & now have the android tablet nice to know which app works well on P38 will put it all together
over the weekend if I get time.
Thanks Cannon

ps Cant help myself when it comes to Gadgets!

[TheTree]

Hi

According to DashCommand on my iPhone i too have pretty high long term fuel trims.

I will be interested to see what happens to them after my service and tuneup.

Steve

[glenhendry]

Hi

According to DashCommand on my iPhone i too have pretty high long term fuel trims.

I will be interested to see what happens to them after my service and tuneup.

Steve

Any change SteveFarmer? I still have this issue, and I suspect low fuel pump or inlet manifold gasket leak. I will be measuring the fuel pump output today.

[clubagreenie]

For reference, the D2 Thor, both 4.0 and 4.6 cuts out cold fuelling at 55degC. Found this out when I was testing the Freelander 82deg thermostat and had consumption issues that turned out to be unrelated.

[TheTree]

Any change SteveFarmer? I still have this issue, and I suspect low fuel pump or inlet manifold gasket leak. I will be measuring the fuel pump output today.

Hi Glen

Unfortunately I currently have no way to reset my long term fuel trims, my nanocom budget has been severely dented by a set of ECB Dimpled and grooved front discs, plus "greenstuff" pads.

So I either need to find someone with the kit, or wait until my budget refills :p

Steve

[clubagreenie]

Where did you get the rotors and pads from.

[Keithy P38]

Sorry to steal the thread, and butt in Steve!

I got drilled and slotted rotors from Island 4x4 - Specialists in Land Rover and Range Rover Parts and accessories for all models. UK and worldwide mail order. - Island 4x4 - Specialists in Land Rover and Range Rover Parts and accessories for all models. UK and worldwide mail order. (http://www.island-4x4.co.uk) and pads as well. Their prices are very good. Freight is a tad exxy, but all up was much cheaper than buying in oz.

Cheers
Keithy

[TheTree]

Hi

I looked at the UK suppliers but then discovered that RDA Rotors & Drums Australia + EBC Brakes, The Big Brakes Company | Home (http://rdabrakes.com.au/) have them in OZ and their prices are pretty good.

So I decided to buy them locally, I like to support local distributors when I can , but am not prepared to pay silly prices !

Steve

[glenhendry]

I got my pads, rotors and calipers from FWD motors in Yeerongpilly Brisbane. Good crew of guys and good prices.

Stevefarmer, your long term fueltrims will definitely display the current situation even without resetting the adaptive values, it just means that it could take days instead of hours.

BTW, my fuel pressure at the rail is 50psi after checking three times with a handheld cheap tyre pressure gauge. I wouldn't bet on super high accuracy with this device, but that seems like good pressure to me for fuel at the rail so now to check the inlet manifold gaskets.

[TheTree]

I got my pads, rotors and calipers from FWD motors in Yeerongpilly Brisbane. Good crew of guys and good prices.

Stevefarmer, your long term fueltrims will definitely display the current situation even without resetting the adaptive values, it just means that it could take days instead of hours.

BTW,my fuel pressure at the rail is 50psi after checking three times with a handheld cheap tyre pressure gauge. I would bet on super accuracy,but that seems like ggood pressure so now to check the inlet manifold gaskets.

Glen

Thanks for that, I will check them again in the next few days

Steve

[Pedro_The_Swift]

Hmm Ok,, so the LTFT are a guide as the O2 sensors fix any faults??? yes?
I'm not sure WHICH O2 sensor ( on the torque app) readout to use,, eqivalent?
but even then any abnormal readings may just be the sensor adjusting for bad LTFTs ???
but they should read 1,, on a good day;)
I am getting faults on both O2's but were only replaced 2 months ago.

fauly codes to come.

and how are all these readings affected by my running LPG??:confused:

[glenhendry]

Your LPG ecu will steal the O2 sensor feeds and then send a bogus O2 signal to the petrol ECU in an attempt to stop the petrol trims movings while running LPG. Note this does NOT work as my Thor ecu is not fooled by the LPG fake signal.

[Pedro_The_Swift]

Hmm ok Glenn,,,,,
so ---
the LTFT display is only ever for PULP??

is there a test for the O2 sensors?

[Hoges]

On the Torque app "Bank1 -sensor 1" is the sensor for cyls 1,3,5 & 7 Bank 2 Sensor 1 cyls. 2,4,6,8 so look at O2 sensor "1" for banks 1&2. There is no sensor "2" because the Aust. market did not require post-cat sensors at that time.

There is a test for the sensors providing the ECU supports it...

If you go to the "Help" button and search on "Test" there's a description of how to go about it for the O2 sensors. I'm indisposed at the moment so can't get to the vehicle to "connect and report"

[bee utey]

Your LPG ecu will steal the O2 sensor feeds and then send a bogus O2 signal to the petrol ECU in an attempt to stop the petrol trims movings while running LPG. Note this does NOT work as my Thor ecu is not fooled by the LPG fake signal.
This should only be true for mixer systems with simple closed loop controllers. Often the problem is that they are fitted to one bank's oxy sensor only instead of both banks. The vapour injection systems I work on have no need for oxygen sensor emulation. Poor calibration of the LPG fuel map will send LTFTs off the scale though, time for a tune up.

[Pedro_The_Swift]

atm mine are -7 and +14
the only O2 reading I can find is 1.1

Faults kept.
po 134 and 154,
both O2 sensor circuit, no activity detected