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Old 06-22-2010, 09:07 PM   #1
cave dweller
batboy's Avatar
Join Date: Aug 2009
Location: Kansas
Posts: 96
Modding the 2004 LS1 IAT

Please note this is for the 2004 GTO. The 05/06 GTO has the IAT housed with the MAF. That's a different breed of cat, although you can get a breakout harness and a LS1 style IAT, then relocate the IAT on the 05/06. Disclaimer: modify your car at your own risk.

Lately, some folks have been modding their IAT. Basically, you replace the stock thermister with one that reads temp changes faster.

Let's say you are at a long traffic light on a hot summer day and some Mustang in the next lane is throwing you revs or you are staging at the local dragstrip on a hot evening waiting your turn down the track. Most of us know GTOs have issues with heat soak under the hood. A bunch of that hot air is finding its way into your intake. The IAT might be reading 150 degrees on a 90 degree day while idling. Once you get moving, the stock IAT takes a while to cool down. You might be well over halfway down the 1/4 mile before the IAT is reading actual air temp.

There are several thermisters available and I don't intend to debate which is best. I picked the 3,000 ohm model 44005 Omega thermister (see link). It was readily available and fairly cheap. Do some research and find a better one if you so desire.


First thing to do is unplug and remove the stock IAT. I had already relocated mine away from the hot radiator. Carefully use a pair of needle-nose pliers and tug firmly on the connector prongs. The stock thermister should pop out of the housing. The first pic shows the housing with the stock thermister guts removed. The new Omega thermister is shown. You'll need to trim the tiny thin wires on the Omega to the proper length.

Clip off the OEM thermister (the black part). You will need to use something as a heatsink between the thermister and the prong where you need to solder. I used a tiny pair of needle-nose visegrips, but you could use tweezers or surgical hemostats or alligator clip. If you are over 50 like me, a magnifying glass is also helpful. Carefully solder the leads of the new thermister to the prongs. The second pic shows how it will look. No comments about the crappy solder job, it's not pretty, but it works.

Place the new thermister into the IAT housing. Make sure it snaps all the way in. Install the fully assembled IAT on the car and connect the wires. I have HP Tuners, so I was able to confirm my IAT worked.

OPTIONAL On advice of others, I removed the IAT and pulled the thermister back out. I put a dab of silicone on the thermister wires and prongs where it's soldered. I decided that those thermister wires are very thin, so vibrations and bumps and air whistling through the tube at high velocity could cause the thermister wires to eventually break if flexed enough over time. Don't get any of the goop on the tip of the thermister.

2004 torrid red with red interior A4 GTO (1 of 499)
Just bolt-on mods (cam/heads are bolted on, lol)
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