austinglk350

The summer heat is here in Texas and I realize the outside temp reading on the gauge is actually higher than the local forecast and my BMW 325i.

The temp reading on the gauge is 101F
Local weather temp from Radio station is 97F
My BMW 325i temp is 98F

Anyone seeing the same discrepancy? Still think the temp reading higher than the actual. Need some feedback from other folks and on other temp range in other places.

NYCGLK

It all depends where the sensor is and where you park and it also depends where radio's sensor is. 4 degree error is not statistically significant when it comes to weather. Also they are all digital anyways so that adds to an error as well.

TXGLK

i wonder if your GLK's paint color would also affect how slight difference from what the radio is reporting?

Tate

My temp gauge is usually 1-2C degress below what the radio station is reporting. My GLK is steel gray.

I am not too concerned over the 1-2C degrees delta. But it is good to know the temp outside so you can dress up/down when getting out of the car, or know when the road is close to freezing

austinglk350

I have the Artic White on my GLK. Thats is the right color in Texas to deal with summer heat.

Baby G

Depending on where the car is parked and what angle the reading is being done by the sensor usually has the variation. My infiniti is usually of by 1-2 C, but on days on days where I park the car in direct sunlight in summer (past week was just beautiful - 30-34 C), it can go up by 3-4 C. At the end your color also plays its part.

drcollie

Its because the temp sensors are located near the lower part of the front bumper and picking up the heat off the blacktop. That's all it is....

NYCGLK

Silver is good too as it reflects most of the sunlight. I drove silver E-class in summer in southern Europe and car stayed pretty cool in direct summer light (better than my white Toyota). I still haven't had enough sun to figure out if GLK's glass is heat insulated (my guess it's not due to cost saving), I believe that was main reason E-class stayed cool, as even black seats did not heat as much when exposed to sun through the glass.

fraublucher

Temp sensor inaccuracies are deliberate and due to emissions systems. This is not the same as the standard IAT sensor, but an OBD-II integration. They figure that ambient air temps are affecting other componentry such as intake air manifold (under the hood from sunlight) and catalytic efficiency due to roadway temperature.

So by integrating an algorithm (the Benz engineers in der Fatherland showed me the schematic and some coding and then I promptly fell asleep), the system determines other factors which control emissions and power output.

The tip that was slipped to me, and I will be trying this out, is to move the outside air temp sensor to a cooler location. What I really want to do is move it to one of the air conditioning ducts and freeze that sucker. If I can "trick" the OBD system, so the logic goes, my GLK should be able to pick up power. In all my previous Benzes, they run stronger in winter. Chilling the exterior temp sensor may produce an erroneous result on the display, but I will take that ignorance any day for more power. R-R-R-R!!!

Besides, if I really want to know the outside temperature, I trust those dial stick-ons better and will put one on the driver's mirror. Either that, or I can just drive by a bank and look at their sign. If I want to get real high-tech, I've been eyeing these babies for awhile:



I'm off to Germany again after the 4th, so the power-R-R-R-R experiment may wait until after that.

austinglk350

Wow..that's kind of explain why my Accord check engine light went off during winter time and pass all inspection without any porblem. Once the weather get warmer, the check engine light will come back. Been doing that for last 3 years. Very interesting information and definately open the option to get more power...zoom...zoom....

fraublucher

Oh yah, forgot to say... that's why the magazine test cars are always some flashy color, they are faster. The "bad *** black" ones draaaag on hot days.

NYCGLK

I call some and maybe a lot of BS. Any engine runs better in cooler weather, has nothing to do with engineering, has to do with physics. Why do you think we have cooling system and intercoolers for FI ingines. 2 stroke gokart engines run better in cooler weather.

I also find it VERY hard to believe that there is one temp sensor. The sensor measuring temp of coolant is the one that should affect the engine not the one measuring how hot is the air. They can't be the same one sensor.

And white cars are faster than black cars, yea right, maybe by .00001 sec since they do get a bit warmer in the sun.

Manback

while sitting in the sun I believe that cars with outside temp usually are closer to the heat index, and not the acutal temp.

holycaoAMG

Going Off Topic here. but yes this is totally true. Colder weather means colder air. Colder air equals more air ppm(parts per mill). More air ppm means an overall higher combustion. More combustion equals more.. ZRrrooommm!
...just a lil chem and physics explanation

My car is black on black, its the 'hottest' car out there when the sun hits. LOL

fraublucher

Who said 1 temp sensor? The GLK actually has 5 (or 6, I lose track)... the primary IAT (Intake Air Temperature) sensor, the ATS (Ambient Air Temperature - the one that gives the signal we are talking about!), two EGT (Exhaust Gas Temp) sensors, the WT (Water Temperature), and OT (Oil Temperature) sensor.

I have a friend who says "ya gotta type it in crayon". We're talking about the algorithmic A/F (Air/Fuel) ratio change adjustments made by the temperature that provides the exterior temperature display. If you read what I wrote, I think that's pretty clear.

My buddies in Germany are engineers and software developers for Mercedes and they let these tidbits loose to me every now and then.

They have promised me some "easter eggs", little tricks you can do with the computer for extra features that are standard on German market models.

Baby G

Definitely interested in the easter eggs so please pass them on eh..

drcollie

Agreed, in part. But do you not think that Mass Air Flo Sensor is affected by temperature degradation due to rising values in barometric pressure that can affect the Sigma value of the Algoritmic A/G ratio? I sure do....and when that occurs we all know what can happen to the engine....its toast, pure and simple.

NYCGLK

I guess I am not really sure how air/fuel ratio change adjustment affect what you see on the display as outside temperature. And if there are 5-6 sensors as you said then wouldn't there be just one dedicated sensor for ourside temp?

fraublucher

You might be sure if you read all the words in my previous posts, I'm pretty sure I've explained it twice now.

fraublucher

I'll ask my buddies in Germany about the Sigma value.

I'm still going to try it, I don't care if I blow something up, they can get me the "hot" Euro market motor with the "real" hp that our USA cars don't get.

NYCGLK

I see it now

NYCGLK

Looking forward to easter eggs.
Can your buddies confrim that euro features are not on US glk vs. they are there and locked (aka auto closing sun roof in rain, auto tilting mirrors in reverse and whatever else there might be). Maybe they can also confrim "launch control" on GLK that is supposedly locked on US GLK.

reyoasian

It depends on how much sun your car got. When I park my car in the sun (it's black on black), it gets really hot inside. Most of the time in the summer when I just opened my car door and sit in, it feels like I'm in a sauna. Due to the sun, the PARKED car gets really hot, so the car's temperature display is increased by quite a bit once you just start your engine, but once you drive it for a while it becomes more accurate.

P.S. Even from weather forecasts (I don't know about you), I get a "actual temperature" and a "feels like" temperature. In the summer, the "feels like" temperature is mostly higher than the "actual" temperature due to sun, and same with winter it's lower due to windchill.