Relocated IAT affecting gas mileage?
Thread Starter
Race Director
Joined: Sep 2001
Posts: 14,682
Likes: 753
From: NEwhere Ohio
Relocated IAT affecting gas mileage?
Ive been seeing poor highway fuel economy numbers and am wondering if its related to my Inlet air temp sensor relocation.
I have a hotcamm'd, headered 93 Vette - that relies on speed density to supply the reqd amount of fuel.
A couple years ago, I relocated my IAT to right below the air filter instead of in its usual snorkel location.
Lately, Ive been noticing 19 MPG and such for highway trips. I typically hear LT1 and LS1 owners rave about 30 MPG! and such.
I am wondering if the relocation of this sensor is making the computer see lower air temps and send more fuel than is needed.
The other thing too I am wondering about is the extended wires. I think that wire extensions would make for more resistance and also might make the computer think its getting a lower air temp and thus supply more fuel as well. I am assuming higher resistance in the air intake temp sensor means cooler air temps..
However, before any of this, the car has always ran a little rich. I suspect another culprit is my Ed Wright tune.
My question to forum members is...Has anyone here seen better gas mileage when switching their relocated inlet air temp sensor back to the stock location?
I have a hotcamm'd, headered 93 Vette - that relies on speed density to supply the reqd amount of fuel.
A couple years ago, I relocated my IAT to right below the air filter instead of in its usual snorkel location.
Lately, Ive been noticing 19 MPG and such for highway trips. I typically hear LT1 and LS1 owners rave about 30 MPG! and such.
I am wondering if the relocation of this sensor is making the computer see lower air temps and send more fuel than is needed.
The other thing too I am wondering about is the extended wires. I think that wire extensions would make for more resistance and also might make the computer think its getting a lower air temp and thus supply more fuel as well. I am assuming higher resistance in the air intake temp sensor means cooler air temps..
However, before any of this, the car has always ran a little rich. I suspect another culprit is my Ed Wright tune.
My question to forum members is...Has anyone here seen better gas mileage when switching their relocated inlet air temp sensor back to the stock location?
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
I relocated mine back when the car was still pretty much stock, but never really noticed any mileage difference either way. Since modifying and excellent tuning though, I have gotten as good as 26 mpg on the highway which is about the same as it did stock. Mine's an automatic and I assume the guys getting closer to 30 mpg are the 6 speeds, it would make sense. Re/ the wiring, done correctly, one more foot of it should make no measurable difference in resistance. I got a whole new plug w/ leads and so only had one splice per wire instead of the two you would have if you just extend the original one. I'm no expert on this but I've read that there's not really much temperature difference between the two locations but the (air) signal is just more stable, farther forward.
Melting Slicks
Joined: Jun 1999
Posts: 2,949
Likes: 23
From: Bowling Green KY
Basically everything I've read about this mod says don't do it.
If you move it you are no longer measuring the actual temp of the air as it enters the engine, only as it approaches the air filter. The air heats up some before it goes into the engine, this is why that sensor is right in front of the throttle body, to get the most accurate measurement.
These cars run rich anyway (at WOT that is) so moving the IAT only hurts - it thinks the air is cooler than it really is so it provides more fuel than necessary so yes, it could cause a mileage drop.
If you move it you are no longer measuring the actual temp of the air as it enters the engine, only as it approaches the air filter. The air heats up some before it goes into the engine, this is why that sensor is right in front of the throttle body, to get the most accurate measurement.
These cars run rich anyway (at WOT that is) so moving the IAT only hurts - it thinks the air is cooler than it really is so it provides more fuel than necessary so yes, it could cause a mileage drop.
