A 10 days ago I went to the track and experimented with my PR CAI pipe with HKS filter and stock resonator, HKS and resonator, and HKS hybrid. There was no measureable difference so I reverted back to my favorite intake which is the hacked air box with a midpipe. The night I was reinstalling my hacked air box the two wires on my IAT became completely sheared off from the mounting flange/sensor element. They sheared off with no force what so ever which left me to wonder if the wires had been fatigued inside the wire jacket and a slight bump broke the wire jackets. I have removed and reinstalled the IAT many times (probably like 40 time now). Maybe I had a part in fatiguing everything. Being a cheap a$$, I snipped the sensor element off the flange and soldered the sensor element directly to the wires. I then drilled a 1/4" hole through the flange, pushed the sensor element through the flange, positioned the element close to the stock position, and then siliconed the hole securing the wires in place. I then tested the sensor for resistance and everything still worked within spec.

Fast forward to yesterday, I filled up my tank and netted 24.5mpg in 80% city/20 highway driving. This is the same gas station I've always used. The weather has been pretty much the same and I had been doing my usual 2nd and 3rd gear WOT blasts on occassion. For the past year, my MPGs had always been around 21.0-21.5mpg during this kind of driving.

I don't know if the IAT sensor maybe is the culprit, but the car sure seems to be more efficent right now. I doubt the hacked air box changed anything even though the car does feel more lively from 4500-7000rpms.

I suggest you check out your IAT for correct operation. It's a simple test and requires a voltmeter, temp gauge, and hot/cool water.

1) Remove the IAT sensor
2) Fill a cup with hot water to ~160-170 degrees
3) Switch the voltmeter to read OHMs and tap the terminals
4) Put the sensor element in the water. The number should be around .70-.80 OHMs.
5) Pour out the water and add some cool 70 degree water. The number should read ~2.3 OHMs

When I get back home I'll verify the exact OHM numbers.


Dave

 

hmmmm....time to go test at the track again.

 

It would be very interesting to confirm that the IAT does in fact affect performance - there are so many threads out there stating that it gives the ECU information for diagnostic purposes only. Mine is still tied off in the engine bay. I've been lazy and have not yet relocated it yet so it more accurately reads my CAI temp.

 

I notice when mine gets untied and ends up hanging real low nest to the tranny, my throttle response is extremely poor, almost 2 seconds, and actually almost stalls out, and after I move it back to where the cone is, it improves back to normal, wierd weird.

 

Yep, the information concerning this sensor is conflicting. My Chilton's manual says it helps the ECU adjust A/F parameters via air temp readings. The 4th gen FSM says it's used for diagnostic purposes. What exactly Nissan means by diagnostic is not understood, but I do know the dictionary meaning of diagnostic is "the resulting decision". I also know that GM and Subaru systems use the IAT sensors to help adjust A/F. It's not the definitive source for adjusting A/F ratios, but the IAT does help the ECU decide.

These Ebay resistors people put in-line with the IATs are worthless not because the IAT doesn't help the ECU decide A/F, but that the resistor fools the ECU into believing it's colder than it really is. As we know, colder air means the air is more dense with O2 therefore the ECU richens the A/F mixture to compensate for the extra o2 and make more power. If the ambient temp is 90 degrees and the IAT thinks it's 45 degrees, the ECU will run a richer fuel program. Well, a richer fuel program in hot air = crappy performance because of the overly rich A/F. Too many people believe more fuel = more power and that's simply not true.



Dave

 

yeah...report back to us......

 

Are you talking about the ambient temp sensor? Mine is sitting inside the scoop so its getting completely different readings than my intake.

 

Are you saying with the midpipe instead of the resonator? I thought you were all into the resonator?

I need to investigate the temp sensor on my car as I have been getting crappy mileage pretty consistently lately...good info!

 

wow, i barely get 19mpg 99% city

 

That's what I've been getting in mostly city with a few highway runs on the weekend (not many).

 

I was all about the resonator until I went to the track 10 days ago and saw absolutely no change in ET/MPH with or without the resonator. I have since resorted back to my hacked airbox with a midpipe because that's the setup I've always run best with. FYI, the hacked airbox setup wasn't tested that night. The resonator feels better, but that's about it.


Dave

 

Gotcha...thanks.

 

19 mpg is pretty good. 98 se is rated at 21 for city. i sometimes go WOT

 

I get 15-18 MPG mostly city

 

use a bottle of chevron with techron fuel system cleaner. the ones that treat up to 20 gallons. they are 10 bux and come with 3 dollar rebate. its the easiest way to boost ur mpg by 2-3. trust me

i went from 17 mpg to 19 and i only have 25k !

 

The hacked airbox with resonator seem to run better for everyday driving, but not too good for the track IMO. I ran the hacked airbox with resonator at the track a few weeks ago and I was disappointed with the result. I ran faster with my old PR CAI setup. I'm keeping the hacked air box though because I don't go to the track much anyway.

 

I just put my stock air baox back on. Well, sort of. I don't have the bottom half, the one I'm supposed to hack, so it's only the top half. I like it a lot more than the hybrid and to my surprise sounds a lot better than the hybrid too...