Forrest Gump 9

Hehe

The last couple days I've been testing out my self made in car AIT monitor. With the car always display the outside temp on the cluster so I figure why not there, on the cluster.

A piece of double electrical wire about 8 feet long and 4 electrical splices are all you need.

Get under your car, locate the out side temp sensor (driver fog light area), unplug the sensor (save it somewhere so you can reuse later), use two splices and tap into the sensor harness, run the wire up to the engine bay. Use the other two splices to tap into the AIT sensor (it locate in the y hardpipe). That's it you're done.

Turn on the car and your AIT should display, if you run the wires wrong it should show 185 degree. If that the case just switch the wires.

There are two problems I found so far with this. One, the temp will display in Celcius even though the display say F. Two, you no longer can read the ouside temp. But this can be easily fix. Enjoys!!

Evolved8

Nice thinking Pham

nanayaw6

Does this influence the a/c and heater auto controls in anyway or those work solely with the in-car temp senser

Forrest Gump 9

AC has been fine. Stage II I'll have the outside temp sensor hook back up so I can toggle between the two. Heck I'll even go and add a third sensor for the rear tank temp while I'm at it, but I'm too lazy now .

shardul

iTrader: (1)

Hope you are aware of the fact that the ecu selects ign and fuel maps based on the ambient temp reading in conjunction with the a I t reading

Forrest Gump 9

Really? That I did not know. Well, it's easily reverse. And once I hook the outside sensor back then it'll be the same as stock. I'll just toggle it back to see the ait.

GT-ER

How sure are you of this? I have yet to see a single vehicle that used ambient temps for it's tune. Only IAT.

Jakpro1

Not positive but I have heard that as well

urbamworm

Yeah me either, I am not so sure about the validity of that.

pearlpower

Easy way to compare the two; either way like your out of the box thinking.

AMGPilot

Exactly, it's looking for the delta to pick the timing basemap. This isn't a good idea

Forrest Gump 9

Actually after a little thinking, I don't think this is bad at all. If this is true, the ecu will advance timing, right? So in a way I'm fooling the ecu. May be next time I'm at the dyno I'll see if there's any power gain. And just as a precaution may be I'll splash couple gallons of race gas in there.

AMGPilot

No it will pull timing and dump fuel. This is a REALLY bad idea

Forrest Gump 9

Why? I thought the cooler the ait the more timing and fuel right?

On a normal car, AIT always higher than ambient air right? By doing this I'm fooling the ecu to think AIT is as cool as ambient, hence advance timing and add fuel. Wouldn't that means more power?

Forrest Gump 9

The lowest ait I see thus far is 11 degree Celcius. Traction was a major problem .

GT-ER

Again, this is the first time I EVER hear of ambien air temp being used....and I've tuned quite a few cars. Why would ambient even matter? IAT is the only air the engine is seeing.

Jakpro1

HUH, I guess you do learn something new everyday. The Bimmer guys had this same arguement.

http://www.e46fanatics.com/forum/sho...d.php?t=817911

This was posted below and seems pretty valid. Not sure what it means in the end though. The car IS dependent on the sensor or not????

Ambient temperature sensor

The ambient temperature sensor is not directly linked to the engine control unit but to the instrument cluster. The value of the ambient temperature is sent to the engine control unit via CAN bus. In the event of a fault, the instrument cluster sends a characteristic value which the DME interprets as a fault.

If a fault is entered, a substitute value is calculated for the ambient temperature from the intake-air temperature. The ambient temperature is required for many functions in the engine control unit that contain temperature-dependent parameters.

GT-ER

Yes, and I know this to be true but have never seen it affect timing or fuel. Only the IAT does that...at least that's my experience.

xpl0sive

so it seems like my ambient temp sensor has died, or is somehow malfunctioning... it's showing 47 degrees celcius when it's really like 10 outside lol... so my car runs worse? i haven't really noticed a difference.... does anyone have the part number for the ambient temp sensor?

AKnight55

Mine is being weird too.. I think i must have done something when I installed my low beam and fog HIDs, because its reading way higher than it should.. Must be touching something that gets hot

GT-ER

The ambient temp sensor should not affect how the engine runs. I ran mine disconnected for a few days and everything worked perfectly ( except the outside temp obviously ). Even in WOT the car ran just fine with no issues.

xpl0sive

i find that when my ambient temp sensor starts acting up, my AC kicks on... like i have my interior temp set at 22 degrees and when it's just 5 degrees outside it blows warm air. but when the temp sensor starts showing that is 48 degrees outside, my ac starts blowing cold air...