Throttle position sensor wiring help....

[97GsXfreak]

Alright I bought my car with a 75mm throttle body on it so it used a mustang throttle position sensor. Now my problem is I went back to a 1g throttle body in my 2g so I could get a better idle but I have to cut off the mustang tps connector inorder to hook the wires up to the 2g throttle position sensor. I dont know if I should use the 1g tps or the 2g one and how to wire in a connector or hardwire or something.. Thanks

 

[Kevin Jewer]

I don't have any wiring schematics in front of me, but if this is a 2g car I can tell you that you need a 2g TPS. Well, you could use a 1g TPS and wire in the 1g throttle closed switch, but I don't see the point. Either way, the ECU won't go into closed loop idle speed control without that throttle closed signal.

 

[97GsXfreak]

Alright i got a 2g throttle position sensor and I also have the connector so the only thing i need to do is find out which wires connect to the connector wires. So if anyone has a wiring diagram or anything...also another question, I dont have my fiav blocked off nor do I have coolant lines going to my t/b because i couldnt get 2 of the screws out so i just blocked off the coolant nipples on the throttle body is that going to be a big problem? Thanks

 

[Kevin Jewer]

The FIAV will always be open, so it will always be trying to fast idle, even when it warms up. I would either connect the coolant lines or block it off.

 

[dieseltech]

The coolant lines help prevent ice from forming in the throttle body. Yes I said ice. When air passes through the throttle body it speeds up and becomes super cooled air. It can produce ice and cause your car to die when you let your foot off of it. Of course you will only have this problem when there is moisture in the air. If you live in an area where the air is usually dry, such as arizona or texas, you probably won't have any issues. I hope this helps you understand why you have coolant lines running to your throttle body.

 

[Kevin Jewer]

I'm going to dissagree. There are too many poeple running up here in new england through the winters without the FIAV hooked up and having no problems. The manifold and TB are warm to the touch even without the coolant lines connected. The coolant lines are only to operate the wax type valve (like a thermostat) that bypasses more air around the throttle plate and raises idle speed when coolant temps are cold. The speed of air doesn't change it's temperature either, and with the small surface area exposed I doubt it is capable of pulling an appreciable amount of heat out of the TB at any speed.

 

[dieseltech]

http://www.engineeringtalk.com/news/bsc/bsc113.html

Or google Throttle Body Icing.

 

[Kevin Jewer]

I still dissagree. Doesn't mean I'm right of course. But I'll just ramble on a couple of points.

-Without the coolant lines hooked up the TB is still warm to the touch in cold weather, in my personal experience.

-I've never heard of anyone that is not running coolant lines to the TB, or running an aftermarket TB, that has had the TB freeze.

-Our cars pull intake air from the engine bay. Even in sub zero weather the intake temps are significantly warmer.

-The turbo should do a good job of heating the air as it comes in, though at cruise maybe not so much. The turbo is still heated by the exhaust, I'm sure some of that transfers over though. Who knows.

-If the coolant was there specifically to warm the TB, would it not then be circulated through it? It's only fed to the FIAV, and just so happens to warm the TB up some.


I'm just thinking out loud here. Obviously I'm not a Mitsu engineer nor do I claim to know what they were thinking when they designed this system. Even though I didn't run my 2g without the FIAV in below freezing temps, I trust my personal experience and that of others over simply reading about a topic on the internet though. I do intend to eliminate the FIAV on my EVO next week and drive it through the winter, since it interferes with my idle tuning with the AEM...

 

[97GsXfreak]

Alright well i got my tps wired in and everything but still dont have coolant lines hooked up to my throttle body because there are no lines that go to it....the previous owner must have eliminated them. So my question is whats going to happen if i dont put a fiav block off plate because I can't get the bottom half of the t/b off for the life of me?

 

[Kevin Jewer]

The FIAV will always be "open," giving you a constant high idle. The ECU will attempt to compensate with the ISC, hopefully it has enough range. Unlikely though. You might try closing the BISS all the way to help out.

Are you sure the line isn't just looped around? There is one connection on the heat line that comes back from the front water pipe, and the other is on the back of the tstat housing. If they are just capped or looped and not permanently sealed a little 3/8th coolant line will get this project done.

 

[97GsXfreak]

Thanks guys my idle is killing me so hopefully this will do it. Alright I am not sure if this is right but there is a line going from the back of my thermostat housing to almost the end of the waterpipe....is that where the guy looped the connections for the throttle body??? If thats the right connections which line goes to which nipple on the throttle body...a line from the back of the tstat housing goes where and a line from the water pipe goes where??

 

[Kevin Jewer]

That sounds like the right lines. IIRC, the upper one from the Tstat housing goes to the upper TB port, and the lower one from the heater portion of the main water pipe goes to the TB's lower port.

 

[97GsXfreak]

Thanks man I got everything hooked up and its idleing alot better now