Stock Intake Sensor Reacton Test
 

I had my IC out and decided to do a reaction test for the intake sensor. I have the sensor located in the post IC piping. I ran a hairdrier through it and dataloged it. It seemed to take around 70 seconds to get up to full temp. Here is a pic of the log.

That sucks are the aftermarket ones any quicker to react I wonder.
stupid air, and its stupid low specific heat

want me to test my GM sensor?

Please! I am planning on getting the GM one. I hear it is the same resistance values and does react quicker. Can you log it?

Just to chime in, I've done similar tests as follows:

* I removed the sensor from the UIM and suspended it upright using a pair of compression clamps, gripping the connector and not the brass base
* I placed a 70mm IC tube around the sensor so it was floating inside the tube but not touching the walls
* I took my girlfriend's industrial-strength hair dryer and blew it down the tube

The dryer managed to raise the temperature of the sensor to 60C (according to the PFC commander). It took about 4-5 seconds for the sensor to react; after that it climbed at about 3-4 degrees C per second to 60C starting from around 18C. This meant it took well over a minute to read the actual temperature of the incoming air (which was hot enough to be very uncomfortable directly on your hand.)

I then ran two cool-down tests. I let the sensor cool with natural convection (no air flow) and then reheated to 60C and let it cool with forced convection (the hair dryer on with no heat).

In the first case, it took over ten minutes for the sensor to drop from 60C to 37C. In the second case, it took two minutes for the sensor to drop from 60C to 35C. I believe that the second test more closely approximates how the sensor reacts in the stock configuration.

That said, a ramp-up time of 4-5 seconds is totally unacceptable. In my opinion, the function of the stock air sensor is to determine when the IC is heat soaked which takes a relatively long time to occur. The danger here is when large, efficient intercoolers are used that can drop the intake charge very rapidly, say in a track setting. In this case, the sensor may still be reading high temps while the IC outlet may be much colder and more dense. This will cause a lean condition. This situation is exacerbated by the metal-on-metal heat transfer to the sensor in the UIM.

So it's my hope that the GM sensor, mounted right after the IC outlet in a very thin-wall bung, will provide a better reading of intake charge temperature.

-ch

Well one cannot exactly expect instant heat transfer through the brass probe, to affect resistance values, when we're dealing with air here.

The best bet is to find a sensor with the absolutely fastest response (which would mean the most heat conductive probe) and install it in the IC outlet tank.

Also remember, it's better to register colder than it actually is rather than the converse.

Where did you buy it?
 

I want to get the GM fast(er) sensor asap - where can I acquire one? Anyone have a part number?

thx.

Beast

the GM sensor i have is not a brass probe, it is more like a carrot peeler, it has a filament suspended between two points if i remember correctly

www.k2rd.com

Sounds different compared to these
 

This was posted on the datalogit forum:


http://www.034efi.com/components.html http://www.034efi.com/images/airtemp.JPG

Yours sounds different compared to this one, which looks very similar to the stock thermosensor.

?

Also, I don't see the sensor listed on k2rd's site. I have done business with them in the past - is this something they have that isn't on their website?

thx.

Beast

Sounds like a thermocouple would work well here, but to set it up & tune it might take a bit of work.


Brief oversimplified explanation: Thermocouples are formed by fusing two wires (made of different materials) together, and subjecting them to the same temperature. A voltage difference will be induced, it's more accurate than using thermistors (conventional temp. sensors). Unfortuneately , they're sensitive to the temperatures of the entire length of wire, so you'll get some interference from the heat of the engine bay, unless you can find a very good way to isolate the wires from the engine bay's heat. It's also difficult to set up, because they traditionally measure the difference in temperature between the hot end and the cold end. Your readings would change as the temp. on both sides of the wire change.


On second thought, don't worry about thermocouples for now...



Maybe a thinner thermistor might work well, something with more surface area and less material to retain heat. Modifying (shaving) the existing thermistor will change it's resistance though, you'd have to re-calibrate your display. It would be best to find a thermistor that is made of thin material, but still rated for the same range (resistance) as the stock one.


-scott-

^ that is going way out of the way, you just have to use exisiting sensors

http://www.k2rd.com/haltech/accessories.html

Compatitble with PFC?
 

Ok, sorry to be a worry-wart here, but I just want to make sure that the ait listed isn't Haltech specific, but works using the standard scale and is universally recognized by either ecu system.

thx.

Beast

try it and see, i do not know

i would imagine it so, make sure you get the connector too if you plan on using it

Threads on the Air Temp Sensor?
 

The stock FD air temp sensor has 10mm X 1.25 threads. None of the "faster" air temp sensors mentioned in this thread have the same threads as stock. For example, the GM sensor has 3/8" NPT threads.

I relocated my stock air temp sensor to near the outlet of my custom SMIC and of course tapped my new location for stock threads. Many others have done the same.

I'm all for more accurate air temp readings but prefer a sensor with the stock threads. Has anyone identified a faster air temp sensor with stock FD threads?

my advice: learn to use a tap

it's not that hard....

What's Up With That?
 

Maybe I don't get it. I just said I tapped the threads when I relocated my stock sensor. So, I do know how to use a tap. If you have some useful advice then I am listening. If you are just trying to be a wise ass then I wish you would just refrain from posting such comments.

no, wasn't trying to be a smartass, i just wouldn't let the threads not fitting stop you. Air temp measured before the throttle body is useless in my opinion for various reasons, so i do not agree with those methods

your post makes less sense than mine does, why do you prefer maintaining that thread pitch? yes i see that you relocated your sensor to read air that is not going into the motor but traveling to a pipe, but i say eliminate that crappy inaccurate sensor and get accurate readings from the engineered location

Well
 

I have no concerns with the new location of my air temp sensor near the outlet of my SMIC and before the throttle body. Many others have done the same.

The reason I prefer maintaining the stock thread pitch is so I don't have to keep plugging unused holes and tapping new ones.

I'm done with this thread!

Will call k2rd
 

OK you two - stop trying to pee in each others shoes :D

:piss:

I appreciate the advice. I too will need to retap or buy another Greddy elbow. No big deal. Anything is better than the slow moving stock unit.

I'll k2rd and see if they already know if it is pfc compatitble. If so, I'll snag the connector, too.

Jonesboro - I'm also in the Sac area, but have not seen your handle on the forum before. If you ever swing by Autonomic (formerly Checkpoint) let me know.

Beast

not pissing on anyone, but i hate it when people insist their mod is justifyable when they haven't tried anything else

he hopped on someone elses bandwagon of relocating the stock sensor, and my point is, there are better and more accurate sensors

the location is trivial, but at best, stock is more than adequate

with the GM sensor, you are tapping to a larger hole, so it's no biggy, nothing to plug

lol ... stock location for the stock AIT sensor is poor. It would work just fine if the chosen sensor or replacement sensor was shielded or insulated from mani. Argue if you like. lol

Anyone got a recommended part# for a replacement AIT with similar voltage output and I'll give you a big shout out!

In the meantime I'm off to GM looking for a new AIT because my stock relocated sensor still sucks the big one.

the GM is insulated if i remember correctly

Does anybody have test data on the GM sensor?

I just read this thread from start to finish for the first time. It was interesting to see how the discussion about the accuracy of the GM sensor progressed. Initially, people were speculating that the GM sensor has a faster reaction time. Then a couple people offered to do some testing. As far as I can tell no testing was done. However, starting about 1/3 of the way down, everyone seems to have concluded that the GM sensor is better.

Personally I need to see some hard data before I go through the trouble of installing the GM sensor.

I imagine a machinest could reduce the diameter of the GM sensor mount and re-thread it to fit in the stock opening.

i think rethreading anything other than the UIM is a bad idea

i am going to get some test data on saturday, too much school stuff today, and i have a job interview :D

This is coppied from the Datalogit list

--- In Datalogit-FD3S@yahoogroups.com, "ennowein" <ennowein@y...> wrote:
> I'd say reasonably close, as stated I held both stock and
> new unit in ice water and measured both resistances
> (after waiting FOREVER for the stock unit to adjust ...).
> Did the same in close-to-boiling water.
> In both cases the measured ohms were very close.
>
> I have been running the new sensor for quite a time now
> and it seems to read very reasonnable temps and reliably so.
> You will need to splice the wiring harness as the connectors
> are different.
>
>
> --- In Datalogit-FD3S@yahoogroups.com, Christopher Heiser
> <hyperion@o...> wrote:
> >
> > This is great! And you've verified that this sensor is the exact
> > same scale as the factory sensor? If that's the case, I'm
ordering one
> > immediately,
> >
> > -ch
> >