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I'd rather do it myself
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Discussion Starter #1
I was testing the actual value of the air in the intake and comparing it to the OBDII IAT value. What I found is that the IAT is fairly accurate as to the running temp of the air in the intake, but is is very slow to react to sudden temperature changes.

If I floored it the IAT would take quite a bit of time to change. But the test probe I had showed an immediate drop in temperature.

This was all done with mid 50F ambient temps and the IAT showing ~70F or 15F above ambient. The two temp probes read within 2F of each other when at the same ambient temps.

Anyway, it was surprising to see a big drop to near ambient with in a couple seconds yet the IAT did not budge. Only after the turbo had heated up the air a bit and temps coming out of the IC were around 70F did the IAT start to fall, then go back up, There seems to be a great deal of latency in the factory reading.

So you get a big slug of cold air but the ECU does not see it to adjust the fuel or spark. I would think theres some neck snapping being left on the table here.

I searched and came across a thread about a Fast Acting IAT.

Fast acting IAT sensor [Archive] - Club Protege

They had success using the Triumph 955 IAT sensor.

So I need to see if the resistance readings are the same as ours. They probably are.
 

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Since you were a participant in the high iat thread, do you believe the issue is a slow acting sensor rather than delayed readings due to sensor placement? Do IAT's recorded after the sensor relocation trick still appear to be delayed or will they be fairly immediate?
 

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I'd rather do it myself
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Discussion Starter #3
One of two things. It is either the plastic body surrounding the thermistor or it is a programming delay. I'm betting it is the plastic body at the tip retaining heat.
 

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One of two things. It is either the plastic body surrounding the thermistor or it is a programming delay. I'm betting it is the plastic body at the tip retaining heat.
Given that we've heard positive results with members who have done the IAT relocation trick (logged improvement in timing advance) which combined with your results indicates that the relocation still reads accurate IAT's, is it not possible that the relocation trick removes the effects of a slower heating/cooling manifold on the sensor? The relocation alone seems to improve reaction to temperature changes.
 

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I'd rather do it myself
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Discussion Starter #5
I haven't seen any logs of the IAT relocation that include secondary verification of the IAT temperature reading. I do not think giving the ECU false information is an improvement.

From what I have seen the OEM IAT is relatively accurate, just slow to respond to any temp changes. I cannot see how when using the same IAT module this changes due to the location.
 

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Jedi Master
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I haven't seen any logs of the IAT relocation that include secondary verification of the IAT temperature reading. I do not think giving the ECU false information is an improvement.

From what I have seen the OEM IAT is relatively accurate, just slow to respond to any temp changes. I cannot see how when using the same IAT module this changes due to the location.
do u think haltech has this delay?
 

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I'd rather do it myself
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Discussion Starter #7
I don't know if there is any OEM delay. It is only supposition.

I've programed quite a bit of automated industrial temp control circuits. A buffer is usually used as the temp swings can cause to much unneeded "churning", though it is usually just a few seconds.

I really think it is the way the MAP/IAT is made with the outer plastic sheathing over the thermistor.

Just guessing but I bet you could unsheathe the thermistor and get good results.
 

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Jedi Master
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i wonder, but my meth kit had a instant change. when meth started running my IAT dropped, no delay. Could it be because the water when it sprays against the thermostat it allows to heat trasfer through the plastic faster?
 

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i wonder, but my meth kit had a instant change. when meth started running my IAT dropped, no delay. Could it be because the water when it sprays against the thermostat it allows to heat trasfer through the plastic faster?
I think cold fluids allow for a pretty efficient heat exchange.
 

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I'd rather do it myself
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Discussion Starter #10 (Edited)
Yes you are seeing the effect of evaporation with the meth. And this would be evidence that it is indeed the plastic that is holding the heat.

BTW I scored one of the Triumph 955 IAT sensors.
 

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White 2.0T A/T
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Yes you are seeing the effect of evaporation with the meth. And this would be evidence that it is indeed the plastic that is holding the heat.

BTW I scored one of the Triumph 955 IAT sensors.
nice i shall be watching this thread closely
 

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I'd rather do it myself
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Discussion Starter #12
i wonder, but my meth kit had a instant change. when meth started running my IAT dropped, no delay. Could it be because the water when it sprays against the thermostat it allows to heat trasfer through the plastic faster?
Just an aside, alcohol in the fuel does the same thing. It absorbs more heat than just plain gas and will cool off the charge in the combustion chamber.

Properly tuned 2L can take advantage of that though I don't think any of the canned tunes are targeted for E10 specifically.
 

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I'd rather do it myself
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Discussion Starter #13
I got rid of one of the large vacuum hoses in the brake booster line. It is just one large hose now, the one with the check valve in it (very important). I hoped the steel vacuum nipples were a metric thread but they are a 1/8" - 28 BSTP thread. The IAT I'm getting is a M10x1.25 thread.

So either I have to tap and drill a new hole or I try to tap the already threaded hole for the vacuum nipple. Both the 1/8 -28 and the m10x1.25 take the same size hole. Maybe the I can get the aluminum to mash up enough to retap it with the metric thread? Need something to do a practice tap with.....
 

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I'm sure you already know this, but for the love of God please be careful drilling or even tapping your IM. Take it off the car and make sure you buff or file out any hanging filings/shavings, and try to polish/clean the inside as best you can before reinstalling. I'd hate to hear that a shaving got into a cylinder and wreaked havoc!
 

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I'd rather do it myself
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Discussion Starter #16
Actually the threads are so similar and the OEM ones are so deep that it will more than likely just mash the threads into the new pattern. A minor amount of fine aluminum chips maybe because the bottom of the OEM threads are tapered in. I'll use some grease on the tap to catch the shavings.
 

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You got passed by a Girl.
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Try blowing air over the thermistor using a fan. I tried getting another cars reading at Idle to decrease using a AC vent hose to airbox and it did not budge at idle with the amount of idle air moving over it. Made no sense to me then but now it might have more to do with movement over the wire. Just a idea....
 

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I'd rather do it myself
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Discussion Starter #18 (Edited)
I got the sensor today. A two wire connector with the spring wire clip like what is on the oil temp sensor clips right on.

It does work very fast when connected to an ohm meter.

I figured out too that if I take the TB off I can easily clean up any threading debris.
 
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