RE: Intake Air temp sensor question

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RE: Intake Air temp sensor question

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RE: Intake Air temp sensor question - 8/28/2006 3:30:05 PM

ChevyHighPerformance

Posts: 159
Joined: 7/5/2006
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quote:

ORIGINAL: HummerGuy

I took the entire intake system apart last weekend, and there is no temp sensor, just the air intake sensor. There might be a sensor integrated into the throttle body but I doubt it. By that time it probably doesn't matter.

The MAF sensor is removable as shown in Dennis's post. If you still have the stock intake it will be right next to the air box. The connector has five leads. Here is the wiring diagram. The tan and black wires on one end goto the IAT sensor. The other three are for the MAF.

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Post #: 16

RE: Intake Air temp sensor question - 8/28/2006 3:36:31 PM

HummerGuy

Posts: 6684
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Thanks. We appreciate all of this detailed technical information you have for us. It's a great help. How did you get to learn so much about this stuff, or should we not ask and just enjoy the great advice

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Post #: 17

RE: Intake Air temp sensor question - 8/28/2006 3:36:49 PM

ChevyHighPerformance

Posts: 159
Joined: 7/5/2006
Status: offline

Here are two IAT timing adder tables. One from a Silverado SS and the other from a Colorado I5. On the Colorado table below 104 F no timing is added. On the Silverado SS table, below 86F no timing is added until 23F then timing is added. If the Colorado tune is like H3, then unless your IATs are above 104 then any IAT skewing will not be effective while you are moving. I did some testing and with the stock air box, the air temp can get this high (+104F) after sitting at a long red light while it is about 80 F outside. The IAT skewing for me removed the sluggeshness when pulling out.

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Post #: 18

RE: Intake Air temp sensor question - 8/28/2006 4:04:01 PM

HummerGuy

Posts: 6684
Status: offline

So what you are saying is adjustments aren't really made unless the air going into the engine is warmer then 104? Does the MAF sensor have a temp sensor built into it? Where is the temp sensor?

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Post #: 19

RE: Intake Air temp sensor question - 8/28/2006 4:06:14 PM

Dennis

Posts: 7584
Status: offline

Yes....

This is the MAF and intergated into this very same thing is the IAT sensor too.

5 wire connector

The gimmicks on Ebay are a fixed resistor to tell the PCM the intake air temp is cold...so as you see from the schematic (thanks to Chevy) the IAT is shown as a variable resistor on the tan and black wires..as it heats up the resistance goes down.

< Message edited by Dennis -- 8/28/2006 4:15:58 PM >

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Post #: 20

RE: Intake Air temp sensor question - 8/28/2006 4:12:47 PM

HummerGuy

Posts: 6684
Status: offline

Just remember, I am used to working on import engines, so i'm starting to learn that the the way GM air intake sensors are is different then imports. With the imports I have had, there is the mass airflow sensor, then the temperature sensor, and sometimes a third one (that slips my mind right now) all in the air duct.

I have to get my mind out of import mode and learn the American way of doing things

(or GM way)

Thanks for being patient with me. No wonder ImportKiller has that name :)

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Post #: 21

RE: Intake Air temp sensor question - 8/28/2006 4:19:19 PM

Dennis

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No worries Mike..I didn't know either until Chevy mentioned that the MAF and IAT was all in one...

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Post #: 22

RE: Intake Air temp sensor question - 8/28/2006 5:04:54 PM

ChevyHighPerformance

Posts: 159
Joined: 7/5/2006
Status: offline

quote:

ORIGINAL: HummerGuy

Just remember, I am used to working on import engines, so i'm starting to learn that the the way GM air intake sensors are is different then imports. With the imports I have had, there is the mass airflow sensor, then the temperature sensor, and sometimes a third one (that slips my mind right now) all in the air duct.

I have to get my mind out of import mode and learn the American way of doing things (or GM way)

Thanks for being patient with me. No wonder ImportKiller has that name :)

Recently, GM had a separate MAF and IAT. At that time the MAF was in its own housing - the IAT poked into the air box to measure incoming air temps. Then the IAT got integrated into the MAF. Then the MAF/IAT became a separate unit that got installed into an orifice like on the H3.

When you install an aftermaket intake like K&N or Volant you remove the MAF/IAT and reinstall it into the new air tube. Sometimes the MAF becomes slightly out of calibration because the aftermarket intake has a slightly different inside diameter/air flow than stock and the MAF only meters a small portion and gets extrapolated to the whole area. For example with my K&N intake, the MAF reads about 5% less air that is actually entering the engine compared to the stock intake. The PCM soon learns this and adds 5% more fuel (increases the fuel injector pulse width by 5% to get 5% more fuel because it learned that the MAF input is 5% low).

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Post #: 23

RE: Intake Air temp sensor question - 8/29/2006 7:38:15 PM

bogy

Posts: 21
Joined: 8/17/2006
Status: offline

CHEVY,
I have to say you are great source of information - THANKS!

I will hook up this thing and let everyone know what happens - I will put some pics up too.

So, if you see an H3 burning or blown up here you will know it's me - LOL

THANKS MAN!

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BOG

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Post #: 24

RE: Intake Air temp sensor question - 8/30/2006 8:52:57 AM

HummerGuy

Posts: 6684
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I posted this on my other thread but it pertains to this subject as well:

Well, last night I disconnected the battery completely and reconnected it this morning. I let the car idle for about ten minutes and drove off. My tank ran dry before that and it is filled with 93 octane. I only have a K@N filter with a stock air box. Here is what I found:

1) The climate control did some goofy diagnostics where all three LEDs blinked for about 20 seconds while it moved all of the vents into every which position they can possible go. It's kinda cool that it has it's own little self-diagnostics. I never saw that before.

2) The engine was throttling down alot faster then it used to. That was when I first started driving it. As the morning progressed, it started going back to it's old ways of taking forever to throttle down, although it is still a little quicker.

3) You can now hear valve ticking which you couldn't hear before, and I have been using 93 octane for weeks before I disconnected the battery. I always pay attention to the noises my H3 makes. I'm not sure if this is good or bad. I'm assuming maybe it's because it doesnt realize it's 93 octane and it's trying to run the car for 89, or it's just running the engine differently because it now is working a different way.

4) A tiny bit of vibration on the wheel and shifter that wasn't there before, but appeared to have smoothed out by the time I got to work.

So, anyway, yes there are definitely small differences after this, so something did get wiped and reset. Now, the whole 25 mile trip to work was unfortunately stop and go traffic for the most part, so I really didn't get to drive it at highway speeds for more then 5 minutes at a time. I'll see if there is any difference in gas mileage over the next week or so. So far, there is a slight power increase, but not too much.

I did the math and with the average amount of gas I use, it costs me about $150 to $200 a year more to use premium gas then regular. I'm willing to spend the money if it means I'm putting better gas in my vehicle. Maybe I'm just stupid (Don't even go there Dennis ) but so far it's different. Whether it's in a good way or a bad way remains to be seen.

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Post #: 25

RE: Intake Air temp sensor question - 8/30/2006 9:31:43 AM

Dennis

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Okay I won't..But I'm compeled to say; it's not better gas, it's just higher octane and burns slower..may cause carbon build up...but I'm not saying anything anymore.

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Post #: 26

RE: Intake Air temp sensor question - 8/30/2006 9:37:16 AM

HummerGuy

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Don't misunderstand me here buddy. I believe you completely. When this tank of 93 octane is gone, I'm going to reset things again and go back to good old regular, because I know what carbon build-up can do. I don't want to take chances and ruin my cylinders. I'm just testing and tweaking. I should probably specify that more. I don't take THOSE kind of chances with my vehicles. I paid way too much money and put too much time into my H3 customizing it just to screw it up.

So, thanks for the advice, and I really do listen and take it seriously. I am just going to burn through this last tank and go back to normal.

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Post #: 27

RE: Intake Air temp sensor question - 8/30/2006 1:58:29 PM

importkiller

Posts: 7254
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one main reason why regular octane is better than plus or premium is because it is fresher.

Regular octane is the most common used and the gas station tanks are filled regularly, premium tanks aren't filled near as often so the gas in those tanks are older. Outboard boat motors have this problem alot, have to run fresh gas or the old stuff will foul the plugs and just run like crap overall.

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