supergreenNA1

you guys know what i'm talking about. after a few serious engine mods, you fire up the engine and after it warms up... the idle goes up and down.. up and down.. up and down.. up and down. wtf is the deal here? i know someone out there has figured this one out... time to step forward.

jdblack1

standalone

I've heard everything from new map sensors to EACVs and temp senders. I dont know how to fix it. I just hope the standalone will correct it.

Kataku2K3

check these few things to make sure everything is running correctly IACV, PCV valve, FITV, low on coolant, ECT sensor, and the one that has always cost me the most trouble is the TPS. It's kinda good cuz it's easy to fix if it's the problem. Make sure the TPS signal wire has 0.5 volts coming out of it at idle and about 4.5-5.0 at WOT. If it reads 0.5 or above it's most likely something else. If not then slot the two screws that hold it in and back them out a bit till you can rotate the sensor until it reads 0.5 volts. Have fun!

sparkz

The 3 majors things i've seen that cause it are these (usually fixed in this order)

FITV (fast idle thermo valvle) - unbolt the 3 bolts that connect the the underside of hte throttlebody, the whole piece comes off. then unbolt the 2 10mm botls that hold the metal plate. inside, there is a plastic piece inside. just get a flat head and screw it back in.

EACV - just replace with a known good one

TPS - not really usually the case ubt probably needs adjusting.

Chiovnidca

Air in the cooling system and a missadjusted throttle cable can also cause that problem.

Jackson

Or even just set your idle per helms manual.

smokin rubber

so for the fast idle valve fix you just block off the opening?

REX VT

Solder the fuel relay

Jackson

The FITV is self adjusting with the coolant temp, but sometimes can come all the way unscrewed out of the threads to where it cant adjust, so it just stays open.

supergreenNA1

here's an interesting tid bit of info regarding the problem on my car. when i disconnect the connection from the wiring harness to the IAC valve (aka EAVC), the problem instantly stops. in the past i have put a thin piece of metal in between the valve and the intake manifold.. which solves the problem, but i have to give it throttle when the car is warming up or the engine will die. what i would really like to do is fix whatever is wrong so it idles like it did fresh off the showroom floor.