corolla fx16 idle speed varies - Toyota Nation Forum : Toyota Car and Truck Forums

fishgoggles · 10-20-2005, 07:58 PM

my fx16(4age) idles between 400 to 600 rpm high all the time, and seems to vary alot. engine warm, drops to idle, bottoms out about 900, then bounces back up to 1200-1500 rpm. sometimes when it returns to idle, it bounces between 900 and 14-1500rpm repeatedly, but eventually holds steady again at 1200-1500. ignition timing is right on, and diag. doesn't blow any codes. anybody have any clues?
thx.

92MX83 · 10-22-2005, 08:31 PM

Clean out your IASC valve?

AVANT · 10-31-2005, 03:53 AM

Quote:

Originally Posted by fishgoggles

my fx16(4age) idles between 400 to 600 rpm high all the time, and seems to vary alot. engine warm, drops to idle, bottoms out about 900, then bounces back up to 1200-1500 rpm. sometimes when it returns to idle, it bounces between 900 and 14-1500rpm repeatedly, but eventually holds steady again at 1200-1500. ignition timing is right on, and diag. doesn't blow any codes. anybody have any clues?
thx.

It's a coolant related issue. Happens on a lot of 4AGEs. For me, it turned out that it was signs of a blown headgasket

***REN69*** · 10-31-2005, 07:14 AM

Not neccesarily.. I had that problem for a while after I got the intake manifold cleaned out.. my idle bounced up and down from 1000-1300 when I was at a stop light, it was very annoying. The way I finally fixed it was to basically turn up the idle speed with the idle screw while the motor was on, leave it for a few seconds (I had it up to 2000rpm for about 15-20 secs.) then slowly start to drop the idle down with the screw to about 900-1000 and it never gave me that problem again. You're never gonna get rid of the high idle speed on 4AGEs as they like to idle at about 1000rpm normally.

AVANT · 11-02-2005, 04:37 AM

Spec idle for my blue hat 4AGE according to the BYB Toyota Manual is 850.

***REN69*** · 11-02-2005, 06:42 AM

That's the Spec for a brand new 4AGE not a 15yr old motor dude.. ask anyone with a 15++yr old 4AGE what idle speed their motor runs at.. everyone will say 1000rpm.

Trying to get the 4AGE motor to run at 850rpm is a bitch.. it either runs fine at 1000rpm or it runs from 700 all the way down to 550rpm in the summer and then it sounds like its gonna choke and die on you.

AVANT · 11-04-2005, 02:15 AM

I have an 87 FX16 GTS with 291k. Never rebuilt... Idled at 900 just fine, didn't like 850 much though.

But back on topic. If his Ren's idle adjustment doesn't fix your problem, you may need to look at your cooling system. Maybe as simple as needing a new thermostat <$10 part.

Club4ag and MR2OC has a lot of information on 4AGEs, search for "bouncing idle" and youll get plenty of results.

ybzhou · 11-04-2005, 02:55 PM

Quote:

Originally Posted by 92MX83

Clean out your IASC valve?

What is IASC value? Is it something with air intake? How to clean the valve myself?

..yanbo