air temp sesor mod w/resistor

[robertwb70]

I know this has already been done but I cant find much on it-I searched and only got tidbitsI understand the computer thinks cold air and adds fuel+timing-which is good(stock cars are tuned conservetively)someone said just turn the initial timing up for same effect-I know some computer cars advance timing as much as possible at all times others can only retard timing and still others do both but are limited in the amount they can adjust--does anyone KNOW how our cars work?----no speculation please--if you know for sure educate us if not dont add to the confusion

I want to try the resister just for fun what are the specifics?(ohms)

[Aries]

you can't find much info on it because it was found to cause blown motors.

[PGZX3]

sooo advancing timing on a stock car is bad but retarding timing and running a 500 shot of nitrous is fine?????? Sorry, I'm new to the KA24DE....

[Aries]

the problem is that the resistor works fine in warm weather, but when it gets really cold, the computer does not get the signal to add more fuel for the condition and detonation occurs.

[:: orion ::]

Maybe it's different for S13s, but the S14 FSM *clearly* says the Intake Air Temp Sensor is for diagnostic only. No effect on tuning, power, mileage, anything...

So what advantage could this have???

I think this is a myth, perpetuated by the Honda guys who may actually see a gain b/c the MAP based engine management - Our ECU doesn't need to know the intake air temp b/c the MAF measures the mass of air (no matter how hot or cold), with no reference to the temp sensor.

Anyone ever measure gains on the dyno after doing this???

Later - Brian

[Aries]

don't think so Brian.

[:: orion ::]

Care to elaborate?

Maybe dyno #s before and after?

Or any other supporting evidence that the ECU evens uses the IAT sensor for tuning?

Educate me...please.

[Aries]

I mean, I don't think anyone has dynoed the results.

[:: orion ::]

Ok...cool.

I thought for a second you meant "don't think so" as in "you don't know what you're talking about"...

ALSO: My IAT sensor has been off the car for 6-8months with no CEL and no bad running issues, etc...but it is with a JWT ECU, which it seems is a little more 'lenient' about CELs and removing emmisions control and such.

Later - Brian

[yellow_jacket]

I thought people were talking about modifying the coolant temp sensor? Either way it is a bad idea.

[robertwb70]

well,I feel kinda silly as I just remembered at WOT the computer goes into open loop and uses pre-programed data-not the sensors so it really is useless to try this

[Aries]

true

[Calvin]

Maybe it's different for S13s, but the S14 FSM *clearly* says the Intake Air Temp Sensor is for diagnostic only. No effect on tuning, power, mileage, anything...

My '90 has the sensor, but any mention of it is conspicuously absent from the '90 FSM.

[:: orion ::]

IIRC in late '89 they added the IAT sensor and dropped the compression to 8.6:1 or something...I'll see if I can dig up the pic of the service bulletin.

You can tell if you have the lower compression SOHC by the IAT sensor and a couple other things...

They probably had the FSMs printed before the change...

Later - Brian

[:: orion ::]

Here's the pic (borrowed from Asad's pics over on Freshalloy):

[silviaNE]

Hey orion, how are you running hacked maf in conjunction with jwt ecu?

[:: orion ::]

Same as with any stock ECU...

I don't have the JWT turbo program - I still run the JWT N/A upgrade, which is for stock MAF and injectors on a KA.

The timing is WAY too advanced for a turbo application, so I have my base timing at 15btdc to cmpensate and not blow things up.

Based on data logging I've done with a palm pilot, at WOT my total timing is at 28...not too bad for 8psi.

Later - Brian

[Rownan]

I did the resistor mod.. I hate to say it, but I did. Hear me out though hahah. When fudging with my intake system I broke a wire on the intake temp sensor, and had no way to fix it, so I just drove around with the sensor unplugged.. It was giving me an ECU code for this, so in an effort to stop the code from being thrown, I wired in a 3.3k ohm resistor to the harness, bundled the thing in electrical tape and stuffed it where it can't be seen.

Made no difference at all, except the code was no longer tripping. Problem solved!

Timhttp://www.projectaspec.com

[U12 2NR]

Hi guys,

The air temperature sensor DOES play a pretty signifigant role in protecting your engine. It's absolutely true that you won't ever gain power from it.

Your air temp sensor is there to monitor for overly high air temps, in which case the ecu adjust timing to prevent detonation. That is it's only function.

Putting a resistor in it's place is detrimental to your motor because if the air is too warm, the ecu won't be able to tell and you run the risk of detonating. We all know how bad detonation is.

Detonation was what Nissan had in mind when they added the Air temp sensor to the SOHC's because the SOHC's don't have a knock sensor. So this sensor is there to keep detonation in check.