Air Intake Temperature Sensor

[grammawagen]

Hey guys, no time no see!

My buddy was telling me about how on the Saturns, if you do a CAI, the air intake temp sensor needs to be relocated from the inner fender to the tube on the CAI to retain good fuel mileage.

I removed the air silencer, and I have noticed a bit of a drop in MPG. What would removing the air silencer have to do with MPG and the temp sensor???

A bit confused,
THANKS!!

[loudsho92]

Removing the silencer would have no affect. You might want to pull codes to see whats going on. Maybe its the O2s.

[grammawagen]

Hmmm... I just checked the codes, and nothing came up. My mechanic checked the o2 sensors a month ago. Thanks for the advice!!

[qwertz9586]

Could be a placebo effect or bad gas. Removing the silencer would not do anything for power or gas mileage.

[barticus]

could be you like the sound after removing intake silencer so you are hittin higher rpms on average to hear that sound. that was my problem until gas shot up. was gettin about 220 miles to a full tank and recently i have been gettin about 330 miles for just 3/4 of a tank for the last 2 fill ups.

[Sorian]

Lucky if on average I see 240 miles for a MPG of 17-18. I need to see if the o2 needs to be replaced.

[grammawagen]

Thanks for the info, Gentlemen!!

[shoz123]

I have my IAT right before the throttle body. This gives the PCM the most accurate info.

[coneynew]

In searching for some IAT info, I found this thread - so I'll post my question here vs starting a new one.

I have removed a 99 Tec Throttle body, bracketry, air tube and upper air box lid w/ the tec MAF. I also have a spare UIM for a 97 Vulcan. I bolted up the Tec setup to the vulcan intake using the tec gasket w/ almost looks like aluminum. I know I will need to reverse the plug on the TPS, get the cables connected properly and work w/ the Vulcan UIM to open it up the best I can (enlarging the opening). If I do ever install this setup on my 97 Vulcan, I know it won't run right w/o a tune.

Question. The Vulcan IAT is located near the TB on air intake tube, but on the tec setup, the IAT is location on the upper air box lid. I can lengthen the IAT plug harness to reach it, but will this be a concern (being that the IAT is no further awat from the T ?

PS. Another question re: the Composite UIM manifold swap - I know the Gen IV Vulcan composite intake needs some extra fab to work (EGR tube, etc), but did they ever make a composite UIM for the Vulcan exactly like the original metal one ?

[silvapain]

IAT sensors are thermistors, and have a resistance change of roughly 70 Ohms/degree change (ie, for every degree increase in temperature, the resistance drops 70 Ohms). I can't remember the gauge of the IAT wires, but 18 gaguge wire has a resistance of roughly 0.0069 Ohms/foot.

So, you'll need 10 thousand feet of 18 gauge wire to skew the IAT sensor by one degree F. Obviously that's not a problem.

As for the placement of the IAT itself; I don't think it makes much of a difference either way if the IAT is on the filter box or in the air intake tube. The SHO IAT is in the same location as the Duratec (I think they use the same box). The reason might be that the SHO TB is heated with coolant, and the radiant heat from the TB might skew the IAT readings. I'm sure Paul has actually tested placing the IAT in various locations (I know he has placed thermocouples all around the engine to measure underhood temps before) and has used that to determine that by the TB is the best place, so I would defer to his recommendation on that.

AFAIK, the Gen 4 composite UIM is the closest match for the Gen 3 Vulcans. The EGR tube can be customized with two EGR tubes and some TIG welding (I think Hamal was going to try to braze them together). I have used a 3/8" brass compression coupling before to hold two EGR tube halves together in a pinch - not the prettiest, but it works.