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Discussion Starter #1
Re: 2014 JSW DSG
So everywhere I read the temp gauge is not what it appears - not to be trusted.
So, what is the lowdown?
- Is it a gauge or no?
- A glorified idiot light?
- Shows low temp variations but tops out center scale?
- Is it a "dumb sensor" issue?
- Many places say it does not track with VCDS. I have to believe them...
- Where is VCDS getting the data? (same sensor?, different sensor?)
- Is the ECU purposefully "hiding" the data from the gauge?
- Any workaround using existing instruments (I don't want an an additional gauge there)
- When will the gauge move off-center
- how hot will it get before issuing a warning?
And of course, the overarching question, the one no one has the answer for: Why?
[sarc] Do gauges and MT count as driver distractions these days? [/sarc]
frank
ps. (if we get some good answers here, might be a sticky??)
 

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The temp gauge is more like an idiot light that happens to have a needle. When it registers straight up, the actual temp can be way different. VCDS does register the actual temperature, though.

Why? Just makes the temp gauge less distracting. If it starts to climb, you have a problem. If it points straight up, you are within a safe temp range.

A sticky? Not really. Dub temp gauges have been like this for a few generations know.
 

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So first of all, be happy you have a temp gauge. a few jetta sedans from a couple years ago do not even have one.

the temp gauge, like all the gauges on your dash, and all the lights, and all the digital graphic displays, are computer output devices.

the computer has a program that determines what they show you.

there is a little program that takes the values of the temperature read from a sensor in the coolant as it exits the engine, and converts it to a reading to display.

if you were to plot the actual temperature (you can hook up one of several devices to the OBD connector and access the coolant temp from the cars CAN bus) against displayed temperature, it would have a flat spot. based on actual reading, the gauge starts to move from 120 around 120, but moves faster than it needs to, so it reads straight up 190 from when the coolant is over around 165 and until it gets close to 225 or so. this temperature range is well within normal, and we suspect they chose this to not alarm the casual driver for no reason. if the gauge starts to go higher than the indicated 190, it does not mean it is automatically an issue. if you were driving up a mountain with a full load in the heat of summer, it could head up without a problem. if it gets to the scale marked in red, you should slow down a bit and let it cool off.

the engine will ring beeps and display a message if you exceed the safe temperatur, so don't worry.

if you want to keep a clean dash and be able to see the actual coolant temperature, and other cool parameters. (which may lead to distracted driving, so you need to take care)

you can buy a PF03 and install it on your car.

http://www.polar-fis.com/

a nice guy in PA sells these in the US.

http://dieseldubs.com/epages/34a903b2-878b-4f62-bbfe-116c3f42b6af.sf/en_US/?ObjectPath=/Shops/34a903b2-878b-4f62-bbfe-116c3f42b6af/Categories/Imprint

Call Les and he can give you pricing.

if you want to take a road trip to inside the northern virginia DC beltway, i would be happy to show you the one in my car.
 

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there is one coolant sensor. ( ok, some cars have a second sensor at the radiator, which can also be accessed, but not mine, and I think perhaps not yours)

the same coolant sensor, G62, is used to generate messages on the CAN bus that tell the various computers and processes in the car what the coolant temp is.

this feeds the process that drives the dash temp gauge, and also feeds responses to queries via the OBD connector, which is how VCDS gets to the info ( or other methods, like a scangauge, OBD wireless dongle to smart phone, or other OBD code reade)
 

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Discussion Starter #5
Thanks Mike and Ol'Rattler.
Way back when, I can't remember which, be it Ford Chrysler or Chevy, had a temp gauge in the dash, but was connected similarly.

Why do I get the feeling the car companies all want to treat us like children -
"there, there, don't worry your pretty little head about something like temperature! " with the pat on the head.

The reason a sticky, is that with two posts (Ol'Rattler and Mikes) I, and just about everyone else, would have a firm grasp on what how, and maybe even why, rather than reading through an endless series of posts with folks meandering this way and that on/off topic.

I just traded in a BMW740 for the JSW TDI for my wife. Her choice. (one with which I agreed).
So I started looking into what I could know about the VW cars. Diagnostics...

(aside - One thing that bothered me was the amount of c^*P that was going on in the 740 AFTER I walked away. Stuff would run for a full 30 minutes from last close of a door or trunk. Actually 30 minutes! Something was sucking down the battery - whether it was the new short commutes, or something. I'd get in the car, and get the Trans Prog message on the dash - transmission limp mode. Of course, right after she brought it home, no problem.**

On the diagnostic machine, the trans controller was found to have gone into limp mode over 1000 times. They were just about to replace the controller, when they noticed the battery was low. Dead, actually. After 5 mos. New battery, no trans prog errors for a long time. Then they started again. Long and short of it, the 740 really doesn't charge the battery until the engine gets to 2k rpm. If the battery voltage falls low, trans goes into limp mode. The CAN BUS "knows" the battery is low, so rather than - lets say delay the shift a little to keep the battery up, or even DISPLAY A MESSAGE THAT THE BATTERY IS LOW, it instead causes the Trans Prog to display. Diagnostics through mis-direction!

** Why when she got back home I see no problem? She just ran the car, and the battery was up! We got to the point where if the message came up, I'd "race" the engine (all of 2.5k rpm) for 30 seconds, shut it off, and restart. Voila! No more Trans Prog message!
)

So if you have the information, JUST GIVE IT TO ME! I'm a BIG BOY NOW! I CAN TAKE IT! (without running the car into a bridge abutment)

Ok Back OT...
Of course, having a temp gauge like that does save the tech support folks at VW a lot rather than trying to explain how one or two needle widths is normal, so don't worry! to the retentive types. Increases customer satisfaction.

So now that the car has almost 4 digits on the odometer, (not counting 10ths) and suffered it's first wreck, I've been looking at diagnostics (thanks for the segue, Mike!) available
Of course VCDS. Doesn't work on my '99 e39 wagon, though...
Torque. Documentation is scarce, and I'd jump if RELIABLE modules weren't $60+... But it would do s-o-m-e-t-h-i-n-g on my e39, but how much on the JSW? Documentation void. Pay to play.
So, Mike, you bring up Polar-fis. From a guy in PA who seems to have near god-like status for TDIs, and you're willing to show it to me? Heck yes! PM me.

Even if it takes a trip across the Mighty Potomac Ocean and venture into the Commonwealth of Virginnee to see such a contraption.
I'll even buy you a pint or two.

frank
 

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Note that the PF03 is made by some folks in Spain, they sell around the globe, and have a dedicated forum.

rather than a sticky, perhaps an article for the TDI Wiki. You can start if you like. :)
 

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Discussion Starter #7
Sounds like you're right about the WIKI.
 

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You can start a page if you like. feel free to use this if you want.



I came up with this sitting in my driveway, idling. then put the temps in a spreadsheet. bottom is in degrees C from VCDS.. side is reading from dash gauge Degrees F.

( I guess I could have blocked the radiator or inplugged the fan and kept going, but did not want to.) (also could hook up a spare sensor to wiring and put in something that can get hotter, could use a heat gun if the point is to calibrate gauge against what the sensor reports on the data buss.)

I also have seen some photos of the gauge with photoshopped calibration.
 

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Discussion Starter #9
Very cool. One of tomorrow's projects. Merci!
 

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The Polar FIS is greeat, and I am happy to have it. I would say however that if you intend to maintain your VW yourself, VCDS should be your first priority. It is invaluable when it comes to diagnostics. Not to mention all the coold modifications you can do with ti. My .02 :)
 

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http://www.myturbodiesel.com/gallery/photos/dash-reading-vs-coolant-temp.1276/

local copy of the figure



This is only the bottom half of the scale,

and mixed a bit, since the bottom is degrees c from the VCDS, and left scale is indicated temp from the gauge, which starts at 120, and has 190 at the top.

A better graphic I have seen someplace has VCDS coolant temps, converted to degrees F, noted on a photo of the temperature gauge, photoshopped into the picture.
 

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The P3Cars gauge does a nice job with coolant temperature and other things, like EGT or boost. I love mine. And now they have a white and red version that might look even better.

Mine in my car and it's reading coolant temperature


New version with white numbers
 

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That is not a VW stereo, is it?
It is! In 2010 you could get the Golf TDI with the RNS-510! I love it! Everyone complained it was too expensive, but it's worth it to me.




on Flickr
 

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Discussion Starter #15
OOoooo! Big screen! Nice looking (not cartoonish) maps. OOOooo.
So, some say the 510 is "slow"... The newer ones with SSD are somewhat faster. Is that an issue for you?

Mine has the RNS315 (2014 JSW TDI w/backup cam ). I find it adequate. Bigger screen would be nice. Ties into the car quite nicely, and really like the SD card slot - fits my entire music collection.
So, is it plug-compatable with the RNS315?
Has anyone upgraded?
What did you gain? (hi-def digital radio?)
Any downsides?

Probably ought to be a new thread... but since I'm the OP, I'm not offended at the change!
Oh yeah, Polar-FIS / KESSY compatible?
frank
 

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^^Hi Frank,

I guess the RNS510 is a little slow, but it doesn't bother me. It can lag with some commands, but mostly I use the steering wheel controls to change stations and that works quickly enough for me. The HD radio with Dynaudio sound is very good when there is good reception. Fortunately I get good HD reception for my entire commute. I would miss that. It's weird how they added HD radio to the newer RCD510, but it's not there in the RNS315. The RNS510 is also beautiful in the car. It just makes everything seem more high end. It also has DVD that can play for the passenger, and a hard drive to store music. I like having different kinds of music stored on the hard drive, the SD card, and an iPod connected with the Midi cable. And the phone can operate through the RNS510, but I use the MFD and steering wheel mostly. It is plug-n-play to add a camera for me, but I haven't done that yet. It looks a little involved running the cables from the hatch to the radio. Maybe one of these days I'll add the camera. The hatch emblem camera for the Golf is really cool.

In 2010 the RNS510 was plug-n-play, but the RNS315 has the bluetooth inside so there isn't a bluetooth device under the passenger seat (I think since 2011 with the RNS315) and that means you need to add that along with a wiring harness. There have also been revisions on the units, both the bluetooth and the RNS510. The revisions added features, but also affect compatibility of the devices. Honestly, I think it looks a little too complicated now unless you're very capable and patient enough to figure out what you need. I think the DIYs on this site detail the swap to the RNS510, but it might be dated now with the revisions that have happened. It really was pretty simple at one time, but the unit itself wasn't/isn't cheap.

I think the Polar-FIS works through the MFD, not the radio. From what I've read, the biggest pain with the Polar-FIS is getting it plugged in under the dash. That's not an easy place to work, at least not for me. Adding the P3Cars gauge is a snap! The P3Cars gauge also looks great in the car.

Ken
 

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Discussion Starter #17
Thanks Ken. Very good info. I had missed the bluetooth change - that would be a PITA. Since the MFD and radio/nav are so integrated, any change to one requires me to enquire about the possible impact it may have on third-party add-ons. I need to look it the P3Cars package just for grins.
frank
 

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Back on the coolant temp topic. There is a claim in the post #3 that the temp gauge needle starts moving up when the coolant temp gets close to 225 or so. However, the other day I was monitoring coolant temp with VCDS while towing and the temp reached 235. The needle has not moved at all. So, we should probably establish new max that triggers the temp gauge needle. I really wonder what that temp will be. Anyone has any clue? Has anyone exceeded 235?
I'm planning to do a test drive next week towing over a longer and steeper hill.
 

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You need to get your motor scanned (preferably with VAG-COM\VCDS) for any error codes logged in the ecu and post them, that will save a lot of guessing and check systems out.
 

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Back on the coolant temp topic. There is a claim in the post #3 that the temp gauge needle starts moving up when the coolant temp gets close to 225 or so. However, the other day I was monitoring coolant temp with VCDS while towing and the temp reached 235. The needle has not moved at all. So, we should probably establish new max that triggers the temp gauge needle. I really wonder what that temp will be. Anyone has any clue? Has anyone exceeded 235?
I'm planning to do a test drive next week towing over a longer and steeper hill.
My needle doesn't start to move from the cold position until around 110F. By 140F it parks at the 190F mark and hasn't gone any higher than that and the highest I have seen is 223F climbing out of Death Valley in June. It was the same thing with my 06 BEW. 235F seems a little high to me.
 
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