Fast Idle Problem - Opinions

[B18BSol]

Thanks for your continued support guys in my on-going quest to fix my POS HONDA! lol just kidding, I love my car...

Anyways, I found this article and it's about Toyota's but I was wondering if it possible could be used to diagnos (spelling?) the problem with mine. Once again, if your new to the board, my engine is a 94 B18B, OBD I of course. Thanks for you opinions here...

Surging Idle

You may encounter a Toyota engine that surges rhythmically up and down between idle speed and about 1800 rpm. The root cause of this problem, which occurs on engines equipped with a coolant-heated fast-idle valve, very often is a low coolant level due to a leak or careless cooling,system service.

Experience shows that this problem is most likely to occur on 1987-91 Corollas, MR2s and FX16s N,,dth the 4AGE engine; 1988-93 Corollas and Celicas with the 4A-FE engine; 1988-94 trucks and 4Runners with the 3N7-1,-E engine; and 1990-94 Tercels mid Paseos xs,th the:3E-E and 5E-FE powerplants.

First of all, the fast-idle valves on these engines, which are mounted on the throttle housing, work in the traditional way. When the engine is cold, the valve opens, bypassing enough air around the throttle blade to establish fast idle. As the engine warms up, coolant heats the valve, gradually closing off this controlled air leA and bringing the engine down to curb idle speed. When these valves fail, they usually stick fully closed (no fast idle) or fully open (high, surging idle speed).

Note that when the fast-idle valve fails to close on a warmed-up engine, the PCM senses a combination of relatively high rpm and a closed-throttle signal at the same time. If the computer detects these two conditions at Operating temperature, it concludes that the engine is decelerating, and begins shutting off injectors-commonly called fuel cut-to reduce decel hydrocarbons (HCs). The fuel cut command causes the engine to surge up and down rhythmically

The easiest way to diagnose this problem is to temporarily remove the closed-throttle signal by opening the IDL contacts inside the TPS/throttle switch assembly. You can do this by opening the throttle slightly or by pulling the harness connector off the TPS/throttle switch. If this stops the surging idle speed, check for low coolant and cooling system leaks first. Maybe someone else serviced the cooling system carelessly and all the system needs is a careful bleeding.

If the fast idle valve still seems to be hanging open, check coolant circulation. Both the inlet and outlet hoses on the valve should feel about the same-- hot. When the fast-idle valve is bolted to the throttle housing on a Toyota equipped with a MAP sensor, testing for a stuck-open valve is easy: just remove the intake tube, start the engine and locate the air inlet hole for the fast-- idle valve inside the throttle housing. If you feel suction at this inlet hole after the engine warms up, it proves that the fast-idle valve is stuck open.

When the fast-idle valve is mounted on the throttle housing of an engine equipped with an airflow sensor, you can't use the test just described because the engine won't run with the air duct disconnected. Instead, wipe off the inlet hole inside the throttle housing with a solvent that dries quickly and leaves no residue. Then cover the inlet hole with a piece of duct tape, reinstall the intake air tube and start the engine. If the engine idles normally with the duct tape in place, that's proof positive that the fast-idle valve is stuck open.

Well, what do you all think?

[302stangGT]

didnt u just post that u fixed it?

[B18BSol]

Originally Posted by 302stangGT

didnt u just post that u fixed it?

It WAS fixed, ran great last night, and then this morning it started doing the same thing again...so I'm about to just find a bridge to jump off of...