Odometer Test Mode Temperature Chart

UK forum for general and technical discussion about the Z3 roadster

Moderator: Gazza

Post Reply
User avatar
Brian H
zroadster sponsor
Joined: Tue 16 Dec, 2008 19:55
Posts: 2502

  Z3 roadster 3.0i

Odometer Test Mode Temperature Chart

Post by Brian H » Sun 14 Apr, 2013 14:27

Using the test mode for the odometer it is possible to determine the running temp of the engine coolant. There are 2 different versions of the test mode depending upon the age of your vehicle, the 15 test mode type and the 19 test mode type. The following test will allow you to determine if you have a engine thermostat issue or temp gauge issue using the 15 test mode type odometer. The 19 test mode type odometer displays the temperature as degrees celsius in test 7.0.

The temperature gauge is a buffered gauge so with the needle sat right in the middle there is a range of 45degrees. Below is a diagram of the gauge and where the needle should sit in relation to the Hex codes given in the test mode on the 15 test mode type odometer.

Image

The following link will show you how to use the test mode Odometer test mode, On the 15 test mode type odometer the test function shows the temperature displayed in Hexadecimal code, the table below translates the Hex codes in to both Celsius and Fahrenheit.
.
Hex CodeCelsiusFahrenheitHex CodeCelsiusFahrenheitHex CodeCelsiusFahrenheit
6D451134F7516722120248
6C46114.84E76168.821121249.8
6B47116.64D77170.620122251.6
6A48118.44C78172.41F123253.4
6949120.24B79174.21E124255.2
68501224A801761D125257
6751123.84981177.81C126258.8
6652125.64882179.61B127260.6
6553127.44783181.41A128262.4
6454129.24684183.219129264.2
6355131458518518130266
6256132.84486186.8
6157134.64387188.6Range11Degrees
6058136.44288190.4
5F59138.24189192.2
5E601404090194
5D61141.83F91195.8
5C62143.63E92197.6
5B63145.43D93199.4
5A64147.23C94201.2
59651493B95203
5866150.83A96204.8
5767152.63997206.6
5668154.43898208.4
5569156.23799210.2
547015836100212
5371159.835101213.8
5272161.634102215.6
5173163.433103217.4
5074165.232104219.2
31105221
Range30Degrees30106222.8
2F107224.6
2E108226.4
2D109228.2
2C110230
2B111231.8
2A112233.6
29113235.4
28114237.2
27115239
26116240.8
25117242.6
24118244.4
23119246.2
.
Range45Degrees
Last edited by Brian H on Mon 15 Apr, 2013 20:06, edited 4 times in total.

User avatar
Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 9984

  Z3 roadster 1.9
Location: Cheshire

Re: Odometer Test Mode Temperature Chart

Post by Robert T » Sun 14 Apr, 2013 23:30

Great work, Brian. :thumb:

I'll give others a chance to comment, then move this to the KB.

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Image

User avatar
Deano1712
Z Register organiser
Joined: Sat 05 Aug, 2006 13:56
Posts: 1392

  M roadster S50
Location: Leeds

Re: Odometer Test Mode Temperature Chart

Post by Deano1712 » Mon 15 Apr, 2013 03:41

It seems odd that the engine temp hex code is falling with rising temperature.
I find it difficult to believe that the needle stays central until 119degC. That is very hot. In my V8 conversion I have the Bmw sensor in the head alongside the GM sensor. The gauge moves off centre anywhere above 98, which is my fan trigger temperature.

Sent from my GT-I9100 using Tapatalk 2
Z3M with a few mods...and a little bit more power

User avatar
XVar
Joined: Thu 24 Mar, 2011 17:58
Posts: 475

  Z3 roadster 2.8
Location: Derby

Re: Odometer Test Mode Temperature Chart

Post by XVar » Mon 15 Apr, 2013 13:31

I think the part about the needle staying central until the engine gets very hot is probably correct, I've read that the Z3 temperature needle scale is weighted so that it's central even when it's hotter or colder than the optimal operating temperature, as long as it's in a pre-defined range. 119c does seem rather high as the upper limit though.
Image
1997 2.8 Z3 | Gallery Thread

User avatar
Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 9984

  Z3 roadster 1.9
Location: Cheshire

Re: Odometer Test Mode Temperature Chart

Post by Robert T » Mon 15 Apr, 2013 16:26

Having the hex values decreasing rather than increasing might seem a little illogical, but it just means that the sensor is likely to be a thermistor with a negative temperature coefficient.

A little maths shows that:

t = 154 - h

where 't' is temperature in Celsius and 'h' is the hex figure (after converting it to decimal).

I too am a little puzzled as 119C being the highest safe value. I would expect the highest value to be a little over the 100C that water normally boils at - it is under pressure in the radiator, so will consequently have a higher boiling point, but to reach 119C without boiling, it would need to be under about 1.7 bar of pressure, which is close to what you put in your tyres! I know coolant is not just water, but contains antifreeze and other additives, but I would not expect it to be quite so high. I run my frog with the fan set to come on at 190F (88C), but that will be a lower pressure system than on the zeds.

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Image

User avatar
Brian H
zroadster sponsor
Joined: Tue 16 Dec, 2008 19:55
Posts: 2502

  Z3 roadster 3.0i

Re: Odometer Test Mode Temperature Chart

Post by Brian H » Mon 15 Apr, 2013 18:37

The hex/temp figures were taken from a BMW Technical Note which for the life of me I cannot now seem to find, the technical note showed temp values agains the hex values when the needle was in the middle position so I calculated from there.

Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Odometer Test Mode Temperature Chart

Post by Dino D » Thu 20 Aug, 2015 00:25

A bit of a thread revival!

I've been looking into my engine coolant temps in preparation for viscous fan removal and found out that my icarsoft code reader was way off so Brian H helpfully pointed out this table and I learned about the dash test.

So from my experience so far I can help answer a few questions raised earlier:
The cooling system is indeed pressurized. It's actually @ 2 bar so essential to ensure that the radiator cap (expansion reservoir cap) is the correct rated 2bar one and not a lower value.

Water should only boil at 121c @ 2 bar pressure (or so the internet tells me).

The temp readings can go as high as 119c and the needle does not move from centre.
(This is on the assumption my coolant temp sensor is working but am in the process of changing that so will see if any change).
According to my dash readout a the car runs around 105c at cruise and as high as 115c at idle. Of course according to the dash gauge this is all normal as he gauge does not move from centre.
Others report their cars running lower temps so I'm looking into why mine is higher.

Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Odometer Test Mode Temperature Chart

Post by Dino D » Thu 20 Aug, 2015 00:28

And here is link to what I think is the technical note:
http://www.bmwmotorsports.org/BMW_docs/ ... verino.pdf
Page 14

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 745

  Z3 roadster 2.8

Re: Odometer Test Mode Temperature Chart

Post by deni2s » Thu 20 Aug, 2015 08:14

Deano1712 wrote:In my V8 conversion I have the Bmw sensor in the head alongside the GM sensor. The gauge moves off centre anywhere above 98, which is my fan trigger temperature.
Fan trigger temperature should be 91C, not 99C if your wiring to fan switch is correct. 91C for low speed and 99C for high speed. Some cars came out of factory with incorrect wiring. Check if brown wire is in the middle otherwise your wiring is wrong and you are at risk of overheating your engine.

Mike Fishwick
Joined: Fri 19 Jun, 2009 11:27
Posts: 1991

  Z3 roadster 2.8
Location: Daglan, France

Re: Odometer Test Mode Temperature Chart

Post by Mike Fishwick » Thu 20 Aug, 2015 11:32

It hardly seems worthwhle to have a temperature guage which is designed to be as inaccurate as this - you may as well just have a warning lamp. Maybe this is why modern BMW cars only have a warning rather than a guage, modern drivers being considered to be incapable of interpreting an accurate guage!
A Z3 is not just for Christmas - it's for life!

User avatar
Robert T
Site Admin
Joined: Mon 12 Jun, 2006 11:35
Posts: 9984

  Z3 roadster 1.9
Location: Cheshire

Re: Odometer Test Mode Temperature Chart

Post by Robert T » Thu 20 Aug, 2015 16:42

Modern drivers are incapable of interpreting traffic lights and indicators. What make you think they will take any notice of warning lights? It won't be long before the car decides it has a problem and either drives itself to a garage or pulls over safely and phones for help.

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
Image

Mike Fishwick
Joined: Fri 19 Jun, 2009 11:27
Posts: 1991

  Z3 roadster 2.8
Location: Daglan, France

Re: Odometer Test Mode Temperature Chart

Post by Mike Fishwick » Fri 21 Aug, 2015 12:14

BMW Connected Drive is almost there already!
A Z3 is not just for Christmas - it's for life!

Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Odometer Test Mode Temperature Chart

Post by Dino D » Fri 21 Aug, 2015 23:51

Found some interesting info relating to higher coolant temps and how BMW now controls them on the N52 engine (3.0 from e90):
http://www.e90post.com/forums/showthread.php?t=829913

Originally Posted by Volasko
A while back a member posted a link to a long detailed report about the N52 engine (http://www.e90post.com/forums/showthread.php?t=788821). There is lots of good info regarding our engines that I found interesting, particularly the design concept of the electric water pump (page 67). It describes that our water pumps move more or less coolant through our engines depending on the situations to maintain different engine temperature setpoints. During spirited driving the temperature of the coolant is kept lower to improve volumetric efficiency and thus more power. During eco mode it keeps it higher to thin out the oil to reduce parasitic losses (ie friction) on the engine to save fuel. Most importantly it shows the different coolant temperature set points and will answer your question quite nicely:

112 deg C ECO Mode
105 deg C Normal Mode
95 deg C Med output mode
80 deg C High output mode

I suggest taking a look yourself as it is described in better detail. Hell you can find out every damn detail about our engines in that report as its 75 pages!! Prepare to spend a few hours reading if you're super technical. Having a degree in mechanical engineering helped

Post Reply

Who is online

Users browsing this forum: Baidu [Spider] and 5 guests