Scanguage II questions

I just got a scanguage II the other day at advanced auto (they have a online $50 coupon-$116 out the door) and I have a few questions.

Does the instant MPG get more accurate after you do a few fill ups? As its reading 35-38 mpg and I know I've been getting 45-48 MPGs per fill up.

Mine is off (low)by 3 mph based on my gps and my gauge is 4 mph higher then my gps so a 7 mph diffrence from scanguage and gauge.

What gauges are most monitoring?

It's definitely verified that my thermostat is no good. It's reading 160-165 while on the hwy. and the highest it went was today 175 with AC on and in traffic. So time to replace the thermostat.

Hyde7278 said:

I just got a scanguage II the other day at advanced auto (they have a online $50 coupon-$116 out the door) and I have a few questions.
Does the instant MPG get more accurate after you do a few fill ups? As its reading 35-38 mpg and I know I've been getting 45-48 MPGs per fill up.
Mine is off (low)by 3 mph based on my gps and my gauge is 4 mph higher then my gps so a 7 mph diffrence from scanguage and gauge.
What gauges are most monitoring?
It's definitely verified that my thermostat is no good. It's reading 160-165 while on the hwy. and the highest it went was today 175 with AC on and in traffic. So time to replace the thermostat.

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The MPG reading gets more accurate the more fillups it has to base its data off of. As for the MPH variance, that is a common issue on MKIV cars... I didn't bother with instant MPG because I prefer tank averages. Also, did you follow the setup procedure for using the MPG function?

I monitor MAF,MAP, TBO (which I believe is requested boost) and coolant temp.

In regards to coolant temp, those seem on par with what I get. Before my TB etc job my ScanGuage would read 185* consistently. After the TB etc job, now my ScanGuage reads 170--175. I purchased my TB kit from a reputable dealer recommend from TDIClub. I'm not worried about replacing my thermostat.

JDSwan87 said:

The MPG reading gets more accurate the more fillups it has to base its data off of. As for the MPH variance, that is a common issue on MKIV cars... I didn't bother with instant MPG because I prefer tank averages. Also, did you follow the setup procedure for using the MPG function?
I monitor MAF,MAP, TBO (which I believe is requested boost) and coolant temp.
In regards to coolant temp, those seem on par with what I get. Before my TB etc job my ScanGuage would read 185* consistently. After the TB etc job, now my ScanGuage reads 170--175. I purchased my TB kit from a reputable dealer recommend from TDIClub. I'm not worried about replacing my thermostat.

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I haven't done my first fill up set up yet I was at 1/2 tank when I got it. So that will be done this week some time.

I can adjust the mph on the scanguage just checking if others have seen it off this much.

Thanks for the feed back

7mph is a huge difference! mine is only off by 1mph from speedo and dead on with GPS

do you have bigger tires?

No stock size tires.

Did you read the instructions? Follow them and all will be well. Don't worry, it'll get better.

I've went through the instructions a few times just wanted to make sure it was because I haven't filled up yet

When you do the fill up don't adjust the gallons to the amount you put in. Do an average of what the SG "thinks" you used and the actual fill amount. Otherwise for the first couple it tends to way over compensate.
Yes, you stat is shot. Notice how cluster gauge will read 190 when coolant is only about 165*??
My SG speed was closer than my speedometer was/is.

Had an idea my thermostat was shot but never logged the temp with VCDS. Have a new one and housing in my tool box.

Have to double check my tire size to make sure there the right size and calibrate the SG to my actual speed

Thanks for the tip on avereging the fill ups the first few times

It takes a couple fillups before things start to get more accurate. If you change anything, like your IQ, it will throw things off again. I wouldn't worry at this point. Give it a few fillups and see how things are at that point...

jettawreck said:

When you do the fill up don't adjust the gallons to the amount you put in. Do an average of what the SG "thinks" you used and the actual fill amount. Otherwise for the first couple it tends to way over compensate.
Yes, you stat is shot. Notice how cluster gauge will read 190 when coolant is only about 165*??
My SG speed was closer than my speedometer was/is.

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That's what I did........ and, if I use the Scan Gauge on someone's car to do a Scan and then forget to plug it back into my vehicle, I start over as Jettawreck suggests .......... two or three tanks and it's back in the ball park!

jettawreck said:

Yes, you stat is shot. Notice how cluster gauge will read 190 when coolant is only about 165*??

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Not to hijack but would 170-175* be cause for replacement??

JDSwan87 said:

Not to hijack but would 170-175* be cause for replacement??

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Yes, that's pushing the edge of replacement as it appears to be staying open longer or opening sooner or both than it should.

Hotter means more efficient operation, of course, within the OE spec temp.

However, keep in mind, the Scan Gauge is no more accurate than the info being sent to it by the Coolant Temp Sensor.

Example: My ALH Vanagon engine temp kept defaulting to 418f. Prior to this, Scan Gauge was showing the running temp to be anywhere from 188 to 193f........ So, I changed the Temp Sensor and still got the 418f default temp. Upon further investigating, I found a wire splice corroded. So, I repaired the splice and presto, Scan Gauge started showing real numbers ........ but, now they stay 195 to 202f.

I re-installed the old CTS and now Scan Gauge shows 188 to 193.

Bottom line, you need some way to verify the temp before changing anything!

Scan Gauge mpg readings are affected by a lot of things. As mentioned, Injection Quantity, EGR duty cycle, etc. Avoid making adaptation settings until you get your mpg somewhat close. Also, since it "averages" your "average" if you calibrate after doing strictly hiway trip (or strictly city driving) when you typically have a mix it will throw the calibration tank way off. Take "average" drving fill ups to calibrate, and calibrate gradually.
Get your mph speed dialed in first.

JDSwan87 said:

Not to hijack but would 170-175* be cause for replacement??

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That's a pretty typical tired 'stat. Get a new OEM or Wahler one. I tried several aftermarket ones and haven't found one that worked well. Maybe just the luck of the draw, but consistently most were under or over temp and erratic.

Have a new wahler t-stat in my tool box just have to get some time to put it in.

My new (well pretty new) Behr t-stat shows 186ºF when fully warm. Winter weather, idling, stop-n-go, etc. will all affect max temps reached. You're not that low but if you just can't get above your 170-175º under any conditions, I'd certainly suspect a slightly tired t-stat. Assuming you don't have any wiring issues (as Andy Bees suggests), most likely your t-stat has fallen off its peak. Were it me, I'd continue monitoring and consider a replacement if it absolutely refuses to get above your current temps. Some here have not had that great of luck w/the Wahler. Many have complained about other aftermarket brands. I would recommend a Behr if you can find it. AutohausAZ has them for a very reasonable price.

Also have a couple Audi/VW t-stats have to check part #'s to see if any of them are the correct ones. There not hard to change out so worst case ill use the wahler one and keep an eye on it.

The temp has been more in the 160-166 range. It only got to 175 when I had the AC on and was in stop and go construction on the hwy. as soon as the construction ended and was able to get moving 70 mph the temps dropped back into the 160-166 range.