SG II Accuracy?
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
Ok will try to make sense of this if possible. Drove about 40 miles.
1. first 5 miles in town really didn't pay much attention .
2. 15 miles interstate 65 mph EOT 204*, fWT 188* constent, ECT 194*-196* this was the mth + 6.
3. 15 miles back with mth normal code. EOT 204*, fWT 188*-190* a few times mainly stayed at 188*. ECT 194*-196* mainly stayed at 196*.
4. 5 miles in town EOT 201* ,fwt 190*-191*, ECT 192*-193*. also mth normal code.
1. first 5 miles in town really didn't pay much attention .
2. 15 miles interstate 65 mph EOT 204*, fWT 188* constent, ECT 194*-196* this was the mth + 6.
3. 15 miles back with mth normal code. EOT 204*, fWT 188*-190* a few times mainly stayed at 188*. ECT 194*-196* mainly stayed at 196*.
4. 5 miles in town EOT 201* ,fwt 190*-191*, ECT 192*-193*. also mth normal code.
Edit: In addition, if the fWT is the value from the PCM times 2, how is it we see a fWT of 191? Odd numbers shouldn't be possible.
New User
Joined: Feb 2007
Posts: 8
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These are the ones that concern me. Presumably the pre-programmed fWT and the user programmed ECT should be reading the same PID from the PCM and doing the same math, yet in this case at least they are producing different results.
Edit: In addition, if the fWT is the value from the PCM times 2, how is it we see a fWT of 191? Odd numbers shouldn't be possible.
Edit: In addition, if the fWT is the value from the PCM times 2, how is it we see a fWT of 191? Odd numbers shouldn't be possible.
fWT is a standard OBDII Parameter ID (PID 05) that was defined by the SAE (Society of Automotive Engineers - which is the group that defined the OBDII Standard) and not by Ford. fWT uses a conversion where you essentially multiply by 1.8 and subtract 40, so odd numbers are possible.
Ford includes PID 1139 to report it's own enhanced version of Engine Coolant Temperature. I'm not sure if Ford uses a different sensor located somewhere else in the cooling system for ECT than what's used to report the OBDII Standard Coolant Temperature, but if they did it would explain the difference between the two.
Edit: Tested ECT and fWT on a Ford F150 I have access to, and both were exactly the same a good portion of the time from ambient (55 degrees) to cruising on the highway (194 degrees). When they were different it was only by 1-2 degrees. Most likely the discrepancy has to do with the fact that fWT has somewhat finer resolution and that the ScanGauge will round fWT to the nearest whole number.
Senior User
Joined: Jul 2005
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I am experiencing the same issues with my ECT readings. New Tstat, due to having low readings on the Scangauge. Now with new one, still only make 192 at best driving it hard. Mostly it sits around 188F. I kind of give up, and I am happy the delta never exceeds 7-8 degrees.
Freshman User
Joined: Feb 2011
Posts: 49
Likes: 0
Thank you!
Mr. DeLong, please accept our thanks for taking the time to chime in, even if you've helped to clarify that my idea was way off base!
So would you reccomend we use the ECT code found here in the thread or the fWT for the best accuracy for our engines?
Also, I know the latest flash programming for our engines monitors the delta between the EOT and ECT, sets a CEL if it gets too high. Would that be something the Scangauge could monitor? That might also help us, being able to see what the engine computer sees and is monitoring.
I don't know if there's a PID for that but I think it would be very helpful!
Thanks again!
So would you reccomend we use the ECT code found here in the thread or the fWT for the best accuracy for our engines?
Also, I know the latest flash programming for our engines monitors the delta between the EOT and ECT, sets a CEL if it gets too high. Would that be something the Scangauge could monitor? That might also help us, being able to see what the engine computer sees and is monitoring.
I don't know if there's a PID for that but I think it would be very helpful!
Thanks again!
Hotshot
Joined: Apr 2010
Posts: 19,061
Likes: 238
From: Saratoga Springs,UT
Edit: Tested ECT and fWT on a Ford F150 I have access to, and both were exactly the same a good portion of the time from ambient (55 degrees) to cruising on the highway (194 degrees). When they were different it was only by 1-2 degrees. Most likely the discrepancy has to do with the fact that fWT has somewhat finer resolution and that the ScanGauge will round fWT to the nearest whole number.
I watched both of these 2 day as well and came to the same conclusion
fWT and ECT PIDS pretty well mirrored each other and only for a breif 1-2seconds were they diffrent and only by the same 1-2 degrees
And as far as I know the 6.0 only has 1 temp sensor and its right B4 the thermostat
Hotshot
Joined: Dec 2003
Posts: 15,368
Likes: 121
From: Stuttgart, Ar
James D.---Since we don't have access to the PID SGII uses for fWT, how about posting it? The only one I can find is the 1139 that you posted earlier in this thread.
I'm hitting easy street
Joined: Nov 2009
Posts: 6,395
Likes: 27
From: Central Oregon
You are correct sir. It only has one coolant temp. sensor. That's why I wanted to know why two different PID's could read the same sensor, such as MAT/IAT2 that we went through a while back. Same temp reading but they update at a slightly different right.
James D.---Since we don't have access to the PID SGII uses for fWT, how about posting it? The only one I can find is the 1139 that you posted earlier in this thread.
James D.---Since we don't have access to the PID SGII uses for fWT, how about posting it? The only one I can find is the 1139 that you posted earlier in this thread.
Hotshot
Joined: Apr 2010
Posts: 19,061
Likes: 238
From: Saratoga Springs,UT
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I'm hitting easy street
Joined: Nov 2009
Posts: 6,395
Likes: 27
From: Central Oregon
I watch the road all day! 350 - 450 miles a day. I see gauges in my sleep! So, I might as well watch some more on the way home!
And reach down and switch from SGII to Torque APP. Got that down pretty darn good now!
At least, since my TA is on the phone, I'm not talking on it!
And reach down and switch from SGII to Torque APP. Got that down pretty darn good now!
At least, since my TA is on the phone, I'm not talking on it!
Hotshot
Joined: Apr 2010
Posts: 19,061
Likes: 238
From: Saratoga Springs,UT
Sean I would have thought that you would have an OBDII spliter by now
are the spliters expensive????
I'm hitting easy street
Joined: Nov 2009
Posts: 6,395
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From: Central Oregon
Not expensive, just conflicting. Have seen where a few folks have tried them, but they can't read the same pids at the same time, so If I'm comparing, or trying to compare the same PID, it just doesn't work.
So, for now, I'll swap them.
New User
Joined: Feb 2007
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Also, I know the latest flash programming for our engines monitors the delta between the EOT and ECT, sets a CEL if it gets too high. Would that be something the Scangauge could monitor? That might also help us, being able to see what the engine computer sees and is monitoring.
I don't know if there's a PID for that but I think it would be very helpful!
Thanks again!
I don't know if there's a PID for that but I think it would be very helpful!
Thanks again!
Coolant Temperature (Degrees F)
TXD: 07DF0105
RXF: 044105050000
RXD: 2808
MTH: 00090005FFD8
NAM: FWT
Junior User
Joined: Jan 2009
Posts: 60
Likes: 0
From: KCMO
Just checked the cold soak temps on mine.
Last ran yesterday about 1:00pm. Checked this morning at 7:00am.
Ambient - 29
fWT - 36
ECT - 36
EOT - 38.2
TFT - 36
Just from reading this thread, I'm pretty convinced that fWT and ECT are the same readings.
Strange that the EOT is a couple degrees higher, and there are others in this thread that show the same. Is this an issue of the sensitivity of different sending units? And if so, I'm not really ready to say that a couple degrees different is close enough because we have no way of knowing if the couple degree variance is consistent throughout the range or if it's a percentage variance. If it's a percentage, and it's off a couple in the 30's, it's going to be way off when approaching 200's.
My situation is: running 70-75, no cargo, fWT=182 EOT=202. The highest the fWT got was 186 and EOT was 204, both for a brief second when I hammered down on an incline. Strange that my fWT would stay at 182 when the thermostat doesn't begin to open until 190. I guess that my thermo could be stuck open, but I'd think I would have pretty delayed time for my heater to come up to temp and I'm not experiencing that.
Last ran yesterday about 1:00pm. Checked this morning at 7:00am.
Ambient - 29
fWT - 36
ECT - 36
EOT - 38.2
TFT - 36
Just from reading this thread, I'm pretty convinced that fWT and ECT are the same readings.
Strange that the EOT is a couple degrees higher, and there are others in this thread that show the same. Is this an issue of the sensitivity of different sending units? And if so, I'm not really ready to say that a couple degrees different is close enough because we have no way of knowing if the couple degree variance is consistent throughout the range or if it's a percentage variance. If it's a percentage, and it's off a couple in the 30's, it's going to be way off when approaching 200's.
My situation is: running 70-75, no cargo, fWT=182 EOT=202. The highest the fWT got was 186 and EOT was 204, both for a brief second when I hammered down on an incline. Strange that my fWT would stay at 182 when the thermostat doesn't begin to open until 190. I guess that my thermo could be stuck open, but I'd think I would have pretty delayed time for my heater to come up to temp and I'm not experiencing that.
Freshman User
Joined: Feb 2011
Posts: 49
Likes: 0
Just checked the cold soak temps on mine.
Last ran yesterday about 1:00pm. Checked this morning at 7:00am.
Ambient - 29
fWT - 36
ECT - 36
EOT - 38.2
TFT - 36
Just from reading this thread, I'm pretty convinced that fWT and ECT are the same readings.
Strange that the EOT is a couple degrees higher, and there are others in this thread that show the same. Is this an issue of the sensitivity of different sending units? And if so, I'm not really ready to say that a couple degrees different is close enough because we have no way of knowing if the couple degree variance is consistent throughout the range or if it's a percentage variance. If it's a percentage, and it's off a couple in the 30's, it's going to be way off when approaching 200's.
My situation is: running 70-75, no cargo, fWT=182 EOT=202. The highest the fWT got was 186 and EOT was 204, both for a brief second when I hammered down on an incline. Strange that my fWT would stay at 182 when the thermostat doesn't begin to open until 190. I guess that my thermo could be stuck open, but I'd think I would have pretty delayed time for my heater to come up to temp and I'm not experiencing that.
Last ran yesterday about 1:00pm. Checked this morning at 7:00am.
Ambient - 29
fWT - 36
ECT - 36
EOT - 38.2
TFT - 36
Just from reading this thread, I'm pretty convinced that fWT and ECT are the same readings.
Strange that the EOT is a couple degrees higher, and there are others in this thread that show the same. Is this an issue of the sensitivity of different sending units? And if so, I'm not really ready to say that a couple degrees different is close enough because we have no way of knowing if the couple degree variance is consistent throughout the range or if it's a percentage variance. If it's a percentage, and it's off a couple in the 30's, it's going to be way off when approaching 200's.
My situation is: running 70-75, no cargo, fWT=182 EOT=202. The highest the fWT got was 186 and EOT was 204, both for a brief second when I hammered down on an incline. Strange that my fWT would stay at 182 when the thermostat doesn't begin to open until 190. I guess that my thermo could be stuck open, but I'd think I would have pretty delayed time for my heater to come up to temp and I'm not experiencing that.
Yup, exactly why I jumped in on this thread, and had the theory about the +6 which was shown to be wrong. I know the scangauge is as accurate as the obd2 because they get the same info. At the same time I still keep wondering about the MTH manipulation, and if a teeny bit of tweaking might be beneficial, but I'm not the expert on the math. James is, and I lean towards his expertise, so I have been running the new ECT above and the newer EOT. Not thrilled with the numbers I get and the delta but they are usually within the 15.
Still haven't had a reason to take the truck for a long steady ride for some good numbers just my work commute, got my fingers crossed!