89IROKCONVERT

I havnt been able to find the info im looking for now az and advanced say the air intake temp sensor is the same as the engine temp sensor but alll the air intake sensors iv seen look the same and look nothing like the temp sensor i go to gm and they pull up a pic that looks just as i thought it would (the cage style sensor with the little ball inside )but of course its discontinued so whats the deal

Guest

The IAT (intake air temp) and the CTS (coolant temperature sensor) are identical in function. Some of the IAT's have a cage with the sensor exposed, some are encased in brass. Either one will work fine, but the open one will of course report the temp changes quicker. Not sure that matters, most of the cars the IAT does little if anything to the fuel and spark.

JakeJr

Max, I've got to question you on that. From a few posts I've read, the PCM uses the IAT reading to adjust the injector "On" time and can richen the mixture measurably in COLD area, up north, where temps can drop to below zero F.

There's another issue, too, that, for example when installing a TPIS MiniRam, the IAT on a L98 gets moved to upstream of the MAF as opposed to being mounted on the underside of the plenum. Also, GM moved the IAT on the LT1to the same area, at least on the 96 they did.

Share with me some more details on your position on this. Thanks

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!

89IROKCONVERT

summit has an msd air intake temp sensor (part # 2320) that looks like it will fit and looks like the oem sensor id like to try this one what do you think

89IROKCONVERT

also does anyone know how i can find out how much my car cost when it was new?

Orr89RocZ

iTrader: (20)

Is there a difference in IAT sensors between the years? I thought some later year cars may have installed the IAT in front of the TB and some are in the plenum. I know some of the newer late model cars use IAT's in the air intake ducting, not the plenum

89IROKCONVERT

well i cant find anything to tell me weather the difference between these two sensors will change how my girl runs i cant belive the aftermarket sensor is as good can anyone tell me what there sensor looks like ?

89IROKCONVERT

she runs like a scalded dog when its cold out but seems hesitant when the temp is above 60 thats probably a sensor somewhere right?

redltcamaro

So what im reading is that i can use a cts in place of an iat sensor? Are they the same part number? I got these two sensors in the same box and cant tell them apart thanks

Damon

One of the things I did to my TPI cars was move the sensor up into the air box. Screwed into the underside of the plenum it would often read just astoundingly high temps esp. after sitting hot for a while in a parking lot, etc. What I did was unplug the original, leaving it in place, buy a new one and extend the wiring up to it.

I can't say the car ran any faster but it seemed much more consistent when it got hot. The difference in observed temps was BIG- like 50* or more in some cases vs. having it in the air filter box. The aluminum plenum area above the engine is very susceptible to heat soak.

Can't say that I agree that a CTS is the same sensor as an MAT (IAT) sensor, though. The mere fact they look different and were clearly intended for different applications would give me pause.

Later cars, like my 94 Formula LT1 had the sensor moved to the rubber intake elbow in front of the TB. Seemed to have less problem with heat soak, but still not great, so I moved it to the snout of the conical air filter I was using as a cold air intake system. Again, not much difference, but maybe a little more consistent when hot.

Which gives me another idea for you- what about a later model LT1 IAT sensor? Sure, it's different than a TPI but that's mostly becuase they aren't screwed into metal- just squeezed into a rubber grommet. But I bet the calibration is still the same as a TPI sensor and it uses the same weatherpack 2-wire connector.

redltcamaro

I don't understand on tpiparts.net it shows both sensors with I believe the same part number please explain how the look different so I can install the right one in the right place thanks

Guest

They're not different on a TPI car, I dont know why Damon is saying they're different. They're not. At least some of the V6 cars (maybe all, I dont know) and the later LT1's (not thirdgens nor TPI) used a sensor where the element was in an open plastic cage, rather than encased in the brass housing. That may be what he is confusing, GM has always specified exactly the same part for both on a TPI car and that is the one that does not have the open plastic cage element.

Here's a reference to just one of many places that will tell you the same thing
http://www.compnine.com/index.php?u=...00&grouptype=B
The parts in question are 14 and 82, both the same AC Delco number. Back when I was selling AC Delco parts in the early to mid 90's, they were the same part number then as well.

Jake, I've never found an adjustment based on the IAT in the MAF based hack I have, but I'm pretty sure that thing is incomplete. Otherwise, GM would never have installed one in the first place. I'm not sure if things have changed on the PROM board, but everything up to about 3 or so years ago said it was not used for anything on a MAF car. Ok... sure. As far as location, GM set the programming based upon the location it was at, and the sensor used (lazy). If you change the location, you will have to modify accordingly to have the car run correct. IIRC most complaints from moving the sensor were about being rich. Imagine that.

Drew

iTrader: (58)

If there was a benefit to putting the MAT sensor in the air box, the GM engineers would have been aware of it and could have just as easily put it there to begin with. As mentioned, the 2.8 and 3.1 in both the Camaro and the Firebird had the sensor in the air box. I can't see GM putting the sensor in the Tuned Port plenum just to mess with us.

jwande

JakeJr - Congrats to you and your son. My brother was class of 1990. Very prestigious and quite an accomplishment to make it through. Not many people understand what it takes.

johnmcillwain

One of them is one wire witch. Is the one on the side of the head the one on the intake is to wire which tells the computer what to do

stealthroc89

I'm glad I found this, I was wondering the same thing since they look alike. Now, which plug goes to which? IIRC the wires are the same color and both come off the passenger side wiring. If I do have them backwards I can cross that off my list of bad idle culprits lol.

Stephen

iTrader: (12)

I replaced my TPI "IAT" sensor (which is nothing more than a CTS), with a V6 IAT, and relocated it out from under the air, heat soaked aluminum plenum, to between the MAF & the TB. I noticed a markedly more throttle response when the engine was hot, because the IAT was not not heat soaked anymore. And I noticed a recorded MPH increase on average, although just 1 to 2. Before anyone says 1 to 2 is just a fluctuation....Normally you'd be right. In my case though, I had been tracking my MPG for MONTHS, over the exact same route. Did the swap & found my average MPG went up, for months afterward. So yes....I fully believe it gave a MPG increase.

IAT Relocation Writeup

JakeJr

[QUOTE=madmax;4714581
Jake, I've never found an adjustment based on the IAT in the MAF based hack I have, but I'm pretty sure that thing is incomplete. Otherwise, GM would never have installed one in the first place. I'm not sure if things have changed on the PROM board, but everything up to about 3 or so years ago said it was not used for anything on a MAF car. Ok... sure. As far as location, GM set the programming based upon the location it was at, and the sensor used (lazy). If you change the location, you will have to modify accordingly to have the car run correct. IIRC most complaints from moving the sensor were about being rich. Imagine that.[/QUOTE]

I'm not a re-programmer so I can't say what's programmed in the PROM and what's not, not specifically. I just used common knowledge that the air temperature is one of the parameters the ECM and PCM uses in calculating the A/F ratio. Injector "On" time and ignition are two of those. Both systems to which I was referring were/are MAF, not Speed Density.

As far as what re-programming is required once the AT sensor is moved from under the plenum to the front of the engine and with the Mini-Ram installation and kits seen offered in the catalogs, again I don't know, not being a re-programmer.

However, IIRC when I had PCMFORLESS re-program a few PROMS for my L98 I wasn't asked on the order sheet whether I'd moved the AT sensor or not.

Going for memory on this so, of course, I could go back and re-check Alvin's order sheet from the year 2000 or so. Maybe he's asking that question now, I don't know, since I've changed to a LT1 which are re-programmed by Bryan not Alvin.

To avoid un-intended consequences, I always use the sensor/sender designed for the job it's intended to do. Trying to use a sender/sensor/switch in a job it wasn't designed to do just introduces too many variables for me.

Jake

ASE doc

The IAT and CTS are different. They will not interchange. Try plugging the CTS connector into the IAT if you want verification. I have had this issue when trying to use an IAT connector to repair a damaged CTS harness. They look very much alike but youll find them just different enough that they wont work. The CTS connector is black, the IAT connector is gray.

The ECM makes large AFR adjustments to CTS voltage almost linearally. The IAT on the other hand has a small affect inside of extreme cold or hot. Someone mentioned extreme cold climates. That is where the IAT comes more into play, or in extreme heat.

Stephen

iTrader: (12)

Apparently I achieved a miracle then, since I did the swap that you say is not possible. Read my post above for a link telling how to do it.

ASE doc

Did I say that swapping in a different IAT sensor was impossible? I dont think so. I said that CTS and IAT are different and they are. They look the same and have the same value range, but they are different. Sure you can modify the connector to fit, but without modification, it doesn't. The ECM also responds quite differently to one than it does to the other.

Good idea to swap in the newer design and move it to the air box. GM thought of the same thing on its later models.

Stephen

iTrader: (12)

Or instead of modding the IAT to fit the connector, just replace the stock IAT connector with the CTS connector.

It is interesting the GM put the IAT in the 3rd gen V6 Camaros filter Y-piece, yet put the IAT under the TPI plenum. So the V8 Camaro guys have it easy. Just grab a 3rd gen V6 filter Y-piece, and put the IAT there.

eagle_eyes

iTrader: (3)

friend of mine used to wire in reisiters inline of his IAT when he went to the track. gave the car more timing that way. you can see an increase in MPG too. there used to be a box you could buy on ebay that did basically the same thing. i wouldn't leave it on all the time though, since it's tricking the sensor.

Guest

Sheesh.

On a V8 TPI car, NO THEY ARE NOT! They are EXACTLY THE SAME PART. GO LOOK IT UP! It is not that hard. Use the GM parts book if you want to, you will find the truth of the matter. SAME PART.

Guest

Oreilly
IAT- BWD WT3000
CTS- BWD WT3000

Autozone
IAT- Duralast SU109
CTS- Duralast SU109

RockAuto
IAT- Standard TX3
AC Delco 213928
Airtex 5S1018
CTS- Standard TX3
AC Delco 213928
Airtex 5S1018

Napa
IAT- MPE TS4052SB
Echlin TS4052

CTS- MPE TS4052SB
Echlin TS4052

Or from AC Delco's website
SENSOR,ENG COOL TEMP
Part Number: 213-928
Product Notes:
[Manif Air Temp Sensor]

Eh? ENG COOL TEMP... Manifold Air Temperature? What a concept.

Come on, this is not rocket science. There's no AC 15326386 for a CTS and AC 15326386 for IAT. Part numbers dont work that way, if its the other sensor like the V6 style (this is the open style with a GRAY connector as opposed to BLACK like TPI cars have) its a different part number. GM only uses 7 or 8 digit codes to identify part numbers. If the 8 digit number is the same, guess what? Same part. Thats why all the part numbers as shown above are exactly the same, because the two parts are IDENTICAL.

ASE doc

Wow! After only 20 years as a GM tech am I really that far off. Read carefully so you dont misinterpret this. The GM IAT has a GRAY connector that without modification will not plug into the BLACK CTS. This is not supposition, this is fact. The aftermarket doesnt support the TPI IAT because it is so similar to the CTS. Therefore they sell a CTS to replace it. In order to use the replacement part you must modify the GRAY factory IAT connector.

However, for several years, GP Sorenson did actually make a replacement IAT, with the GRAY connector receptacle that accepted the factory connector. It was always a PITA to find this part because every dillweed parts counter expert would insist on selling me a CTS.

Im not perfect. I can admit when Im wrong. But on this I am not wrong. I have put together way too many TPIs and have dealt with the difference between IAT and CTS way too many times to mistake the two.

Guest

I dont see you posting up part numbers as proof. Until you do, you dont have much to offer. I posted up numbers, even AC Delco numbers off their own website. The first time I worked on a TPI car was in 1987, so I have more than your 20 years based on what you said. That statement in and of itself is completely meaningless though, because all that matters is the part numbers. Those tell the true story. Go look it up, get a printout of the GM blowup diagrams with the GM part numbers shown on it. Then post that up with your "20 years" of experience as a reply of proof.

Guest

Here's what a TPI IAT looks like in the wild (unfortunately the picture doesnt really show the OE sealant on the sensor but its there), what the OE harness looks like (dust/dirt should be sufficient evidence this part is original), and what the business end of the connector looks like. Funny, this is the same setup my 85, 86, 87, 88, and two 89's have, plus the various other TPI's I've worked on, not to mention the number of TX3's and 213-928's I sold for 7 or so years for replacements as an IAT to repair shops and dealership personnel were never coupled with complaints of me being a "dilweed" nor did they return said parts because they didnt fit. Knowing as you do that the gray colored connector wont just plug into the black sensor, or vice versa, one would think the complaints would have been rolling in repeatedly. Never happened.

Guest

Here's the one off the 88. Black connector. Imagine that.

Somewhere I have the air canister off an 86 2.8 MPFI Firebird that has the gray sensor (what those came with originally) that I will take a shot of as well if I can find it so you can see for yourself what the difference in the connectors is. I'm sure its nothing a knife or dremel cant fix permanently.

stealthroc89

Both were black on mine, before the hsr the sensors hadn't been touched, I swapped them over to the hsr (off the engine) and was left with 2 plugs that are exactly the same. Which goes to which?? Hell if I know! What I know supports madmax's view, so if anyone can prove otherwise please do so, it would help alot of people.

Guest

Ok, found the part.
This is what the gray colored sensor looks like. Note the red dots, I photoshopped those in to show where the black and gray are different. You could either use a drill to round those spots on the sensor, or grind that area away on the black connector and it'll plug in just the same.

Oh BTW... isnt a single person in this post that is 100% correct. (only dancing smilie I could find)

Tony89GTA

iTrader: (7)

I have one of those V6 cage sensors and one thing I can tell ya those things are slow to react to changes in intake temps, on a boost run on my car it might move up a couple of degrees, needless to say I was kind of disappointed.

ASE doc

For those referring to this thread for information on the IAT versus MAT and planning to perform the reloaction, I need to retract my above statements concerning the difference between the MAT sensor and the CTS on the TPI engines. These sensors are the same. GM put the MAT sensor where it is because of concerns with high underhood temps and their affect on MAT air temps.

For those who like myself have addressed the underhood heat issue with functional hood louvers and lower T-stat, cooling fan temps, relocating the IAT could be benefitial. You will find that the later IAT sensor with gray connector will have a nylon tip with screen, surrounding a small thermistor. This design is much more effective at measuring air temp. This gray body sensor will require that you modify the OE connector as prescribed in this thread. I appologize for my ingnorrance and even more for my stubbornness.

Guest

I think GM made a design change in 90 or 91 to the other style. I havent confirmed that yet though.

NufNuffZ28

iTrader: (10)

Yes they did, you're correct. The newer style ones with the gray connceter respond faster and are recomended to be used with megasquirt for that reason.

Standard part number AX1 for the IAT with the gray connecter. The coolant sensor is Delphi part number 213-928.

Also, as you stated I believe, if you go to a parts store and ask for an IAT, you will get the coolant temp sensor...

Guest

I suspect its because the SD cars actually have some use for the IAT beyond startup routines.

MC305SS

Those ebay things are resistor pots.
Just take a 4.7K ohm 1.2 watt resistor and place it inline, no sensor at all.
OBD2 which are much less rudimentary than OBD1 allows a tad more time on the injectors and a tad more timing doing this, but will eventually compensate some for the trickery.
We've data logged this on OBD2 systems in the past and saw just minimal gains to be had. The IAT really doesn't input to much into the overall tune and you can run all the time with just a resistor in place.

ASE doc

Those running an EBL or otherwise programmable ECM will find gains by correcting for inlet air temp. Cooler air has a higher concentration of oxygen molecules and will want more fuel to produce optimum power. In order to benefit from this, you will need to move the IAT to the air inlet tube where it can measure actual incoming air. This move was part of the change made on later models. 90-91 sounds about right.

Of course all of this is really dependant on reducing underhood temps. If your cruising around town on a summer day with your non-functional hood louvers, OE T-stat and 224 degree fan on temp, the air temp in your TPI manifold is so high that your engine almost vaporlocks. That's why the early TPIs had the MAT in the plenum. To compensate for high manifold temps. These cars really benefit from lower operating temps and venting underhood heat.