free (almost) timing advance "kit"

[ka24de_510]

ok guys, here it is.the kit that people pay as much as $20 for on ebay...

parts:a 3.3K ohm resistor. go down to radio shack. you'll most likely have to buy a set of them, it should run about $1.29. if you can buy only one from somewhere (anywhere) besides radio shaft, a single should cost 5 cents. the colors for this resistor should be orange, orange, red, and the last color isn't all too important.

directions: bend resistor into U-shape. find your air temp sensor, it should be right next to your MAFS. disconnect the harness from the ATS. there should only be two wires attached to it. (if there are three, you've got the MAFS. put it back.) insert one lead of the resistor into one plug, and the other lead into the other plug. it doesn't matter which way. tape it all over with electrical tape so that it stays clean and put together.

that's it! make sure your loose unused harness stays out of the way of belts and other goodies. I would recommend leaving the harness in the engine bay so that you can quickly go back to stock if necessary.

other side notes:as mentioned previously by someone: try a potentiometer- cheap variable engine timing.from the inside of the intake hose, the air temp sensor looks like a little bridge attached to the side of the hose. there is a thermistor (little orangish temp-sensitive resistor) underneath the bridge, along with some other little thing. (capacitor?)

[Streets_of_Fire]

so what exactly does this do pelase?? thanks!!

[s13sr20chris]

ok, just to be clear nissan says the intake air temp sensor is only for diagnostics of engine coolant temp sensor. that would mean that it has absolutely no effect on ignition timing or a/f ratio. now, some guys swear that they have made gains with this mod. i cant prove them wrong. nissans ecm logic is proprietary and they have been known to keep a lot of stuff private so maybe there is some secret ign changes made according to the iat value. just so thats clear, i have never been a believer in this mod. please dont take offense as i am very glad you are thinking about your car and trying stuff. also note that many other manufacturers openly use the iat for a/f and ign timing.

[InsanityInc]

I'm guessing that OBD1 240's don't have an air temp sensor?

[s13sr20chris]

i dont remember which ones do and which ones dont. its the little two wire connector with the sensor that is in the airbox. i think my 89 did not have it as i dont remember throwing it out ever.

[benemorius]

My '90 has it.

[p00t]

i dont remember which ones do and which ones dont. its the little two wire connector with the sensor that is in the airbox. i think my 89 did not have it as i dont remember throwing it out ever.

This whole IAT sensor situation is alittle confusing... however I have a theory, and well, I'm gonna make you listen to it!

Theres a technical bulletin from nissan pertaining to the early 240sx. It shows the changes make to 89.5 and 90 year SOHC. It shows the compression change from 9.0 -> 8.7. As well as the addition of an IAT sensor. Im also guessing along with it....an ECU reprogram to use the sensor OR that the ECU does read it if its there... but can function without it. My car is a 93 and it does not have the temp sensor but does have the harness connector... My friends 91 does have the sensor. I believe nissan changed over to IAT for 89.5 - 91/92, then changed back during 92 and 93.

Not sure why...

But what i dont understand is why you would mess with resistors to raise your timing... when theres a timing adjustable distributor right infront of you... get a timing light and do it right!

EDIT:whoops also forgot to mention that if you have an IAT sensor your SOHC has 8.7:1 compression. while the earlier 89's without it have 9.0:1.

also a link to the bulletin (mid page) http://wac.addr.com/auto/240sx/240sx.html

[s13sr20chris]

hey poot, do you know if the change in compression was due to different pistons or head or what? i am wondering where the comp change occured.

[p00t]

hey poot, do you know if the change in compression was due to different pistons or head or what? i am wondering where the comp change occured.

99% sure it was just the pistons. Im assuming this because if you swap either piston into the DOHC you get around 11.1:1 or 11.5:1 compression. The only thing changing in that case is the piston itself... nothing else.