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Brad
Dodge Dakota
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11/03/2004
11:19:58
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 Subject: Intake air temp
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Message:
Can anyone explain why it is an advantage to move the sensor located on the intake of number 2 cylinder on a 5.2, and position it in the air intake plastic piping?
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99bludak
Dodge Dakota
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11/03/2004
12:10:29
|  RE: Intake air temp
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The premise is that the engine will read a lower air temp and increase the fuel in the mixture. It works, but I don't think that you will get any huge gains or anything, and you could possible end up using more gas. It is located in the intake so that the truck knows the temp of the air just before it enters the cylinders so that right amount of fuel can be added by the injectors. I haven't moved mine on my 5.2 and don't plan to. Others have moved it and said they saw a performance increase, but I think it is all subjective.
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daffydak
GenIII
11/03/2004
13:00:38
| RE: Intake air temp
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the main reason that people move it, is that it gets a more accurate reading. it sits in the intake manifold that reaches 195+ degrees, so the computer thinks it's intake air is really hot. so the PCM leans the fuel mixture slightly, and causing a slight loss of performance once the engine is warmed up. If the IAT is relocated into your intake tubing it's isolated from the hot intake manifold, and able to read closer to the actual air temp.. I'm pretty sure all it does is richen the fuel mixture slightly, but I think you may gain a tiny bit of timing as well...
00 CC Sport Plus 4.7L 4X4 Auto, 3:55 LSD
Flowmaster orig. 40 series (2 chamber) muffler, adjusted tps to .76V, ported TB, home brew intake setup w/K&N filter, more mods to come!!!
Dan
MOPAR=More Power!!
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99bludak
Dodge Dakota
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11/03/2004
13:37:44
| RE: Intake air temp
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I have to disagree. I don't think that you will gain timing from making the mix richer. Also, that sensor is in the correct place. The air passing through the manifold will rise to approximatelty the same temperature of the intake itself. Also, that sensor has a plastic housing which isolates it from the manifold so it doesn't draw too much heat from the metal. The actual sensor sits out in the open of the manifold, so it is measuring the temperature of the air as it enters the cylinder, which is what the computer needs to add the correct amount of fuel. Not saying that some get improvment from moving it, but it is only due to more gas in the mix, which in the long run is not good on the engine.
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daffydak
GenIII
11/03/2004
14:15:28
| RE: Intake air temp
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Message:
thanks for clearting up the timing issue with that, I thought the IAT could slightly control timing as well. my mistake...
There has to be at least some heat conducted to the sensor from the manifold... check the resistance of the sensor, and compare it to an IAT resistance/temp chart. I did this when I had my 3.9L, and it read somewhere in the 170-190 range (its hard to get an exact reading) and I had a 180* thermostat in that truck...
just my .02
00 CC Sport Plus 4.7L 4X4 Auto, 3:55 LSD
Flowmaster orig. 40 series (2 chamber) muffler, adjusted tps to .76V, ported TB, home brew intake setup w/K&N filter, more mods to come!!!
Dan
MOPAR=More Power!!
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99bludak
Dodge Dakota
JOIN HERE
11/03/2004
14:58:20
| RE: Intake air temp
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Message:
True, there is some temp transferred to the sensor I am sure. However, you have to remember that the air is flowing through that manifold and picking up the heat from it, so it is reaching near the temp of that manifold before it enters the cylinders. It is just my opinion (and probably that of the engineers that placed the sensor) that the computer needs to know what the temp of the air is just before it enters the cylinders in order to keep the mixture right.
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waste of time
Dodge Dakota
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11/03/2004
15:54:35
| RE: Intake air temp
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From Service Manual
During Closed Loop modes, the PCM will monitor
the oxygen (O2S) sensors input. This input indicates
to the PCM whether or not the calculated injector
pulse width results in the ideal air-fuel ratio. This
ratio is 14.7 parts air-to-1 part fuel. By monitoring
the exhaust oxygen content through the O2S sensor,
the PCM can fine tune the injector pulse width. This
is done to achieve optimum fuel economy combined
with low emission engine performance.
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daddio
Dodge Dakota
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11/03/2004
16:04:59
| RE: Intake air temp
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Message:
moved my IAT from the intake to the airbox. no performance gain but, took a hit in mpg so i moved it back. i've read on here that some trucks like it and others don't. it's not hard to reverse if you want to try it for yourself.
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daffydak
GenIII
11/04/2004
00:22:26
| RE: Intake air temp
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Message:
ooohhh 99bludak, I see what you mean now. the PCM needs the temp of the air as it enters the cylinder. I don't know why I didn't think of that myself :-P
00 CC Sport Plus 4.7L 4X4 Auto, 3:55 LSD
Flowmaster orig. 40 series (2 chamber) muffler, adjusted tps to .76V, ported TB, home brew intake setup w/K&N filter, more mods to come!!!
Dan
MOPAR=More Power!!
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