Air Charge Temp Sensor Install

[A.J.]

I know a lot of people have posted some pics on what they've done but not a walk through write up. This is for those that haven't done it yet. The (what pin does the charge temp sensor go to on the 60 pin connector) crowd. Doing my own cals now I'm going to turn on the IAT (Intake Air Temp) sensor. I want to only have to have one cal for summer and winter. The summer time I stand a higher chance of detonation with it about 115 in the summer. So I'm hoping the IAT sensor will help that out. I've read some people relocating it to the intercooler plumbing so that's where I decided to put it.

I cut the boss from some metal stock I had lying around with a cut of wheel.
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Any kind of fabricating needs a drill press.
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I highly suggest cutting oil, for cutting, drilling, or tapping. It saves the tool your using and helps speed up the cutting also.
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After tapping
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I cut a groove to fit on the i.c. pipe.
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On the 60 pi connector the IAT sensor uses pin # 21. On my van with a T-I harness the #21 pin needed to be drilled out. Sorry for the bad picture. The other wire on the IAT sensor goes to PCM ground/pin#4. I just tapped into the Black/Light Blue wire off of the TPS.
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I have a bunch of wiring harnesses I robbed a pin out of.
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A.J.

[johnl]

Nice work AJ. Thanks for taking the time, planning the pics, posting up.

[BadAssPerformance]

Nice job :clap:

Looks like an article for the KC

[A.J.]

Something I forgot. The '88 charge temp sensor and the '89 charge temp sensor are two different part numbers. '88 is a metal housing and '89 is plastic. The aftermarket makes plug pig tails for most GM style weather pack connectors. I went with the '89 sensor because I had that end. I got it off of an Isuzu V-6 (they use GM connectors) when I was working for an Import junk yard. I have the part number at my shop for the '89 pig tail. I'll try to remember it tomorrow and post it for those that can't find one in the junk yard. The charge temp sensor you can get from TU or any parts store.

A.J.

[cordes]

Nice writeup. You have been busy with these lately. :thumb:

[JuXsA]

nice writeup. I plan on doing this in the next few weeks myself

[A.J.]

Nice writeup. You have been busy with these lately. :thumb:

I'm self employed (auto repair shop) and it's slow so I have time to work on my own stuff.

The part number I got from Car Quest for the '89 sensor pigtail is S-556 which crosses over to 57-4501.

http://i42.photobucket.com/albums/e301/thebest4/DSCF0058-1.jpg

http://i42.photobucket.com/albums/e301/thebest4/DSCF0060.jpg

A.J.

[88shadowpjct]

does it matter which wire from the pigtail goes to #21 and which one goes to ground?

[rbryant]

does it matter which wire from the pigtail goes to #21 and which one goes to ground?

It doesn't actually matter which wire you connect to ground vs the computer. The sensor is just a variable resistor so it will read the same either way.

Generally the ground wire will be black with a blue tracer if just to keep things consistent.

One other thing to note is that not all sensors have the same ohm range. For instance the GM sensors have the same connector but they won't read the right temperature because they have a different range. Our sensors read around 10k ohms at room temp.

I am actually running a Cherokee sensor on my build because it is a 1/4 NPT thread which I already had on my intake manifold. I think the Neon sensor is also 1/4 NPT which will also work.

-Rich

[Stinkbox]

I just threaded mine into the extra plugged hole on the side of my aftermarket Vacuum block.

[RoadWarrior222]

Nice work, I'd just be all: sensor, thin nut, washer, rubber washer, hole, rubber washer, washer, thin nut, tighten, done.

[rbryant]

I just threaded mine into the extra plugged hole on the side of my aftermarket Vacuum block.

Honestly, that doesn't seem like a good way to do it. I would recommend against that and I would move it to a location on the intake or the post intercooler charge pipe.


The vacuum block will get the correct vacuum and pressure but the air is likely very stagnant in the block and is unlikely to be the same temperature as what the engine is consuming.

The CTS needs to be somewhere that air actually flows by it so that it accurately represents the air flowing into the intake ports.

-Rich

[shadow88]

Another FYI, if anyone has an O2 sensor bung, it's the same thread as the charge temp sensor.

[RoadWarrior222]

IF you force it....

O2 bung should be M18x(I forgot) whereas CTSs are 3/8 or 1/4 NPT.

[rbryant]

IF you force it....

O2 bung should be M18x(I forgot) whereas CTSs are 3/8 or 1/4 NPT.

Most race shops also sell NPT bungs. I have used aluminum weld bungs from summit on a bunch of stuff and they are nice and easy to work with.

-Rich

[cordes]

+1 for the charge temp sensors being NPT. All of mine are 3/8ths.

[zin]

As a side note, if you want it to respond to changes quicker, you can spin it in a lathe (or the T-M equivalent) to thin out the tip, less material means the response time will be reduced, moving it up stream will give it a head start with similar effects... Of course, it seems like the code might be using this input more as an "Intake Manifold" temp sensor, rather than an actual "Charge" Temp Sensor... BUT, I'm not to the point I'm doing my own cals yet, just a "dangerous idiot"*

Mike

*Dangerous Idiot: One who possess the knowledge to re-adjust things without sufficient knowledge to know the exact effects of said adjustment!:evil:

[rbryant]

As a side note, if you want it to respond to changes quicker, you can spin it in a lathe (or the T-M equivalent) to thin out the tip, less material means the response time will be reduced, moving it up stream will give it a head start with similar effects... Of course, it seems like the code might be using this input more as an "Intake Manifold" temp sensor, rather than an actual "Charge" Temp Sensor... BUT, I'm not to the point I'm doing my own cals yet, just a "dangerous idiot"*

Mike


The charge temperature sensor should already be open element with the actual sensor exposed and only enclosed by an open plastic cage.

If you have a brass tipped sensor then it is probably actually a coolant temperature sensor. A coolant temp sensor will "work" but it will suffer form slow response times because the brass will act as a heat sink compared to the open element design.

Here is a picture linked from the Megasquirt megamanual. The open element design is on the left and the coolant sensor is on the right. These are GM sensors but you get the idea.

http://www.megamanual.com/v22manual/cltiat.jpg

There were also some enclosed plastic CT sensors on the early T1 cars that are also not as good as the open element ones.

-Rich

[shadow88]

IF you force it....

O2 bung should be M18x(I forgot) whereas CTSs are 3/8 or 1/4 NPT.

Not mine. It goes in by hand easily.

[shelbymonster]

The charge temperature sensor should already be open element with the actual sensor exposed and only enclosed by an open plastic cage.

If you have a brass tipped sensor then it is probably actually a coolant temperature sensor. A coolant temp sensor will "work" but it will suffer form slow response times because the brass will act as a heat sink compared to the open element design.

Here is a picture linked from the Megasquirt megamanual. The open element design is on the left and the coolant sensor is on the right. These are GM sensors but you get the idea.

http://www.megamanual.com/v22manual/cltiat.jpg

There were also some enclosed plastic CT sensors on the early T1 cars that are also not as good as the open element ones.

-Rich

i was wondering the other day wth was that sensor on my t1 log intake , next time ill use that one

[zin]

There were also some enclosed plastic CT sensors on the early T1 cars that are also not as good as the open element ones.

-Rich

Yeah, that's what I've come to expect on GM cars, but it's not what I've seen on the TMs I've messed with... If it's already that way, it's good to go IMO...

Mike

[rbryant]

Yeah, that's what I've come to expect on GM cars, but it's not what I've seen on the TMs I've messed with... If it's already that way, it's good to go IMO...

Mike

There are open element ones for our cars but it might only be on the later TII cars or something.

The Neons also have an open element type as do Cherokees but they are 1/4" NPT.

I have also noticed that some mitsu powered cars don't seem to have the correct ohm range.

-Rich

[zin]

There are open element ones for our cars but it might only be on the later TII cars or something.

The Neons also have an open element type as do Cherokees but they are 1/4" NPT.

I have also noticed that some mitsu powered cars don't seem to have the correct ohm range.

-Rich

Do the Neon one' have the correct resistance/temp range? If so, I have no problem using one, I assume they are more responsive.... BUT, if the code is skewed to take the lag into effect, it might not do much...

Mike

[RoadWarrior222]

Not mine. It goes in by hand easily.

If a spark plug will screw in it, you've got an M18 sensor from somewhere, if it won't, it wasn't an O2 bung...

[rbryant]

Do the Neon one' have the correct resistance/temp range? If so, I have no problem using one, I assume they are more responsive.... BUT, if the code is skewed to take the lag into effect, it might not do much...

Mike

Neon/Cherokee sensors are the same ohm range.

-Rich

[A.J.]

I think the Neon/Cherokee sensors are going to be different ohm/temp range compared to the turbo cars because the air charge will get a lot hotter being under boost.

When I was working for an import yard I did a couple of 3.2 engines in Isuzu Rodeos. They used GM temp sensors so I took them out of the core motors. I hooked up ohm meters to the Isuzu N/A sensor and the Mopar Turbo temp sensor and heated them up. The readings were very different from each other. They gave out different ohm readings for the same temp and I think (not positive this was a couple of years ago I did this test) the N/A sensor didn't change or give a reading at the higher temps like the turbo sensor.

A.J.

[RoadWarrior222]

I think the plenum air temp sensor (3/8 NPT) on early 3.0s is around the same range as the coolant sensor FWIW

[rbryant]

I think the Neon/Cherokee sensors are going to be different ohm/temp range compared to the turbo cars because the air charge will get a lot hotter being under boost.

When I was working for an import yard I did a couple of 3.2 engines in Isuzu Rodeos. They used GM temp sensors so I took them out of the core motors. I hooked up ohm meters to the Isuzu N/A sensor and the Mopar Turbo temp sensor and heated them up. The readings were very different from each other. They gave out different ohm readings for the same temp and I think (not positive this was a couple of years ago I did this test) the N/A sensor didn't change or give a reading at the higher temps like the turbo sensor.

A.J.

The Neon sensor is still a 10k/ohm at ~70 degrees sensor.

I will check to make sure that it has the full temperature range of the TD sensor but I am pretty sure it is the same. There isn't anything really special about a turbo vs NA sensor other than that the turbo really needs it to be open element. I have a heat gun that should get it them hot enough to test and I have two ohm meters so I can heat them both and make sure they track.

The GM sensor is totally different.

-Rich

[rbryant]

I think the plenum air temp sensor (3/8 NPT) on early 3.0s is around the same range as the coolant sensor FWIW

I think I found the 3.0 coolant sensors to be a weird ohm range. I originally grabbed a couple from the junkyard from 3.0 engines and when I ohmed them out they were not 10k (can't remember what they were) so I didn't use them.

Has anyone checked the tables in the 3.0 SMEC vs the 2.2/2.5 SMEC to see if they expect the same or different ohm ranges?

-Rich