High idle

[90GSX16g'd]

Ok guys here's my problem.. i just got my enigne back in and started it up.... instanly it rev's really high. I'm not sure how high because the tach went out all of a sudden. It use to work fine when i tore it apart. So i am asking what could make it idle so high and make the tach quit working too.

Thanks,
Scott

 

[awdrst]

It could be your throttle cable stuck or not adjusted properly. It could be a vacuum leak if its pretty big. Maybe your isc is stuck open. Thats about all i can think of right now if i can come up with any more ideas i'll let you know. Im dealing with the same problem right now. When i figure it out i'll post it also.

 

[90GSX16g'd]

the throttle cable is not stuck but how would you know if it was adjusted properly... and i can't find any vaccum leaks.

 

[awdrst]

You just want to make sure that the throttle cable is not so tight that it holds the throttle plate open. Have you tried to set your idle with by adjusting the biss screw?

 

[90GSX16g'd]

not yet ... it revy's up to quick and i don't wanna blow the motor so i shut it down pretty quickly

 

[BaddAssGst]

check your high idle switch... i know when i first start mine, it wants to idle at like 2500 but once it gets warm, it idles about 900. the switch sits on top of the throttle body, on the firewall side. i just leave mine unplugged because if i plug it in, it surges all the time.

 

[Turbo Talon DL]

Check your fast idle air valve(the thing that the coolant lines run into on the t-body). THAT MUST have the coolant lines running to it or your car wont idle properly. Next, check your idle switch like the previous post said. If you dont plug this in, your idle will be pretty high. I had lots of problems like this and it took a while to work them all gone. Try those things first before you start buying stuff

 

[fastwaytech]

With my 90 NT car, I put my foot under the gas pedal, and lift up, and the idle went down. THat's how I found out it was throttle cable.

This is after monkeyinf with all the other shit; ISC, TPS, etc..

Cable is the easiest thing too!

 

[90GSX16g'd]

Well i checked the throttle cable and the sensors and none of that made a difference.

 

[92redman]

check your high idle switch... i know when i first start mine, it wants to idle at like 2500 but once it gets warm, it idles about 900. the switch sits on top of the throttle body, on the firewall side. i just leave mine unplugged because if i plug it in, it surges all the time.

That is just a bandaide for the real problem. This switch let's your ECU know when you are at idle so it can adjust outputs accordingly. You really should leave it hooked up.

Try this instead:http://www.vfaq.com/mods/BISS-1G.html
Once your idle is screw is set properly: http://www.dsmtuners.com/forums/search.php?searchid=644347 read through some other people's solutions to idle problems.

 

[awdrst]

I just wanted to post up that i figured out my high idle problem. It turned out to be my fast idle air valve. I blocked it off and my car idles perfect now.

 

[90GSX16g'd]

I finally figured mine out... it was a seal in between the injectors and the head that i had forgot to put in so i had a major vacuum leak and wanted to keep reeving up... but now it's fixed