- Jul 11, 2013
- 183
are this readings high? ltft stft , and mpg , i have high fuel consumption
- Thread starter yazan
- Start date
The screenshots you showed do not indicate STFT is going to 7. The highest seen is 0.78.
The mpg displayed by Torque is not to be trusted on its own. Only after checking mileage through several tankfulls would I rate my vehicles mpg.
What is of some concern in the images is the coolant temperature. It seems low to me. More commonly seen temperatures for coolant would be say 206° to 212° F.
- Jul 11, 2013
- 183
not shown in the screenshots , but it was , its jumping and playing between numbers -/+
If you are interested in digging deeper into this fuel trim thing here is some little talked about pieces of information. There is not just one set of fuel trim values. In fact there are over a dozen. The values seen at idle are not the values seen while cruising or the values seen under accelration or the values seen under deceleration etc. There is a parameter called fuel trim cell and another called fuel trim index. Many of the DTC codes for lean or rich mixture will use fuel trim index as the definitive parameter. Though I cannot say the PIDs for these that are called out in the "More PIDs for Torque" thread will work for later years, I know they work on the 2002 P10 PCM.
Torque Pro is a fine app but frankly it sucks for data acquisition and analysis. I use Car Scanner Pro when I need to look beyond merely seeing snapshots of values. I think I would record STFT, LTFT, Fuel Trim Cell, Fuel Trim Index, MAP, Throttle position, RPM, and perhaps a few others for review.
I have an errand to run just now, think I will do just that, a recording of values just to see where mine is at right now....
Will post results later today
Torque Pro is a fine app but frankly it sucks for data acquisition and analysis. I use Car Scanner Pro when I need to look beyond merely seeing snapshots of values. I think I would record STFT, LTFT, Fuel Trim Cell, Fuel Trim Index, MAP, Throttle position, RPM, and perhaps a few others for review.
I have an errand to run just now, think I will do just that, a recording of values just to see where mine is at right now....
Will post results later today
- Jul 11, 2013
- 183
i will try to add this in torque app , and please do you mean this app by ovz , there is many similar name apps in play store
https://play.google.com/store/apps/details?id=com.ovz.carscanner
thanks for all the helpfull info up , i just learned the mpg by torque is not accurate .
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and thanks , that app guided me to this topic about choosing obd elm adapters , there is some good info there
Choosing OBDII adapter – Car Scanner ELM OBD2
www.carscanner.info
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You need to look at similar things at a constant medium throttle, hopefully while running down the road (get a hands helper if necessary). The STFT will "oscillate" as that is what the PCM uses to try maintain some air fuel mixture as designed. The LTFT is typically more stable. At idle, one might expect it to be near 0 but it depends on some other operating parameters also. Based on my limited experience / monitoring, your throttle position seems some what low. I have seen normal idle (600ish rpm) at about 20%. Of course, the value can be different as it is more about the PCM attempting to maintain some form of "standard idle" which yours seems to be OK. An important factor in all this is vacuum which you have not posted / captured. That may give further clues. Still further, does your truck have both a MAP AND MAF. IF so, the MAP is used primarily at idle while the MAF has more impact at speeds / running.... but they are "combined" with other things to get to the appropriate cells as was mentioned. IF it only has a MAP, then it is using a "speed density calculation" (iirc) to set running characteristics at various points.
As mentioned, IF the posted data was a result of a good warmup run, then perhaps your coolant temperature is a bit low... but that depends on where you are weather wise although I do see that the intake air temp is quite high so that would likely mean a warm environment which leads to the question of coolant temperature as was questioned previously.
As mentioned, IF the posted data was a result of a good warmup run, then perhaps your coolant temperature is a bit low... but that depends on where you are weather wise although I do see that the intake air temp is quite high so that would likely mean a warm environment which leads to the question of coolant temperature as was questioned previously.
So for an example of the capabilites of CarScanner Pro, and an example of the relationship between LTFT, STFT, and Fuel Trim Index, here is a short snippet of data recorded at a constant 40 mph. The data recording and graphing is done within the CarScanner app as well so it can be handled quite nicely without requiring a helper. Select items to view and concentrate on driving. The data can be selectively graphed later.
- Jul 11, 2013
- 183
If this will show more… This is a new video. The first while parking/idling
the second is while driving with cruise control at 50miles speed with 1500 rpm
If it will help more for better readings.
Another questions. Please. Is this o2 reading are fine?
Engine load?
Regarding The coolant temp? No codes set ever! and some times I feel the hoses are hard ,so it look like the thermostat is working fine!
And its not allways like that. Sometimes while driving in heavy traffic with many stop move and stop lights the temp going to 3/4 the gauge.
MAF?
btw I dont have this kind of maf
I will buy a crc mass air spray cleaner and clean the IAT sensor.
Also I used a can of liqui moly valve cleaner in the fuel tank.
I Replaced fuel filter and changed engine oil.
What else to do?
Thanks all… and sorry for disturbing
Mooseman
Moderator
Those trims look pretty good to me, as well as your coolant temperature. The thermostat has an opening temperature of 190f (88c) so it's spot on. I'm a little concerned about your catalytic converter. In the first video, the #2 sensor which checks the cat's efficiency, is oscillating the same as the #1 sensor however in the second video, it is stable, like it should be. Maybe it was still in warmup.
High fuel consumption can be attributable to a number of things other than the engine itself, like sticking brake calipers, a blocked cat or exhaust or a bad alignment. How much extra fuel consumption are we talking about here? Could also be the weather. IIRC, you're in a hot part of the world? Although your trims are mostly in the negatives, meaning it's taking away fuel, that could be due to thinner hotter air (less air, less fuel needed), which may have the effect of reducing engine efficiency.
Other things to check are the air filter and the plugs. If you do replace them, use only ACDelco 41-103 plugs as this engine is very sensitive to different plugs. Might be worth it clean the throttle body at the same time while disconnecting the battery for at least 30 minutes to reset it.
High fuel consumption can be attributable to a number of things other than the engine itself, like sticking brake calipers, a blocked cat or exhaust or a bad alignment. How much extra fuel consumption are we talking about here? Could also be the weather. IIRC, you're in a hot part of the world? Although your trims are mostly in the negatives, meaning it's taking away fuel, that could be due to thinner hotter air (less air, less fuel needed), which may have the effect of reducing engine efficiency.
Other things to check are the air filter and the plugs. If you do replace them, use only ACDelco 41-103 plugs as this engine is very sensitive to different plugs. Might be worth it clean the throttle body at the same time while disconnecting the battery for at least 30 minutes to reset it.
I don't see anything unusual in the videos. As suggested, you might consider dragging brakes as potentially a cause. Check with a ir temperature reader. You didn't mention what your gas mileage was before you thought someone was "stealing gas".
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Good call on the dragging brakes. I noticed some heat scoring on my front rotors and they were starting to pulse some upon braking. I checked the calipers and they were not releasing very well. I rebuilt all four calipers, front and back. Turned down all four rotors. Greased all the pins and reassembled.
My previous MPG was 16-17 freeway. The last four or five trips over the exact road to my camping spot and back I was getting 19-20. Almost 21 mpg if I wasn't pushing it over 75 mph.
- Jul 11, 2013
- 183
i dont have the DIC in my envoy , so idont know what was the MPG ,and i dont know how can i get the mpg from ? i recently monitor it with torque app but that seem not accurate !
is jacking the car and see if its rotating free is an enough test to know if there is dragging brakes ?
is jacking the car and see if its rotating free is an enough test to know if there is dragging brakes ?
Blckshdw
Moderator
If you have an IR thermometer, you can just check the temperature of the wheels after going for a drive. If one of the calipers is sticking and causing the brakes to drag, it will be considerably hotter than the other wheels.
Mooseman
Moderator
Easiest I found was using the Fuelly website and app.
Fuelly - Track and Compare your MPG
Fuelly allows you to tracks your gas mileage over time, helping you calculate fuel expenses as you drive.
www.fuelly.com