Idle Speed Adjustment '89 Metro - Fuel Economy, Hypermiling, EcoModding News and Forum

SirKeats · 05-23-2008, 09:14 AM

How might I go about adjusting the idle speed in my 89 metro.

After cleaning out all of the blockages in the tubes (see other thread) and replacing the PCV - my engine seems to now be idling faster. I suspect that at some point someone adjusted the idle speed not knowing the engine was being starved for O2... and now that air is flowing properly, the mix ratio is jacked up.

I tried to find instructions in my Chiltons, but as y'all know already - Chilton's blows and I can't seem to find any instructions.

I want to slow the idle down a bit so I'm not wasting so much gas at idle!!

Thanks!

Coyote X · 05-23-2008, 12:34 PM

On the throttle body there is a black cap covering the idle screw. the screw is facing up so it is easy to adjust once you find it. Loosen the jam nut and turn the screw to get it right then tighten the jam nut back. It is easy once you find it

SirKeats · 05-23-2008, 01:07 PM

thanks. just checking... but my 89 has the throttle body right? in my chiltons it says that mine is the EFI which they have in a different category from the throttle body models (think they call it TFI or something like that).

just wanted to make sure we were on the same page. thanks coyote!!!

larryn2o · 05-25-2008, 10:56 AM

some have a screw on the fire wall. it's just 2 hoses and a black tube with a screw. right behind the TBi unit. it only works as a fast idle adjustment.

JohnnyGrey · 05-25-2008, 12:46 PM

Most computer controlled cars have ECU-driven electronic actuators (like stepper motors or solenoids) to control idle. If you've got a stepper, simply unplug it when it's in a position you like. If it's a solenoid, you may have to rig up throttle bypass hoses to get the idle speed you want.

I can't lower my idle below 900 because it will oscillate wildly due to the bouncing of the air to fuel mixture. There are significant fuel savings to be had by lowering the idle. It helps at stops, engine-on P&G and neutral coasting. It's easier to do on some cars than others.

magboy · 01-23-2010, 08:28 PM

I have a 98 Chevy Metro with a 3 cly 5 speed trany I just bought it and it idles a little slow when started, then when it's warmed up it idles way to high. Is the a adjustment somewhere or do I need a whole new throttle body.
Thanks

magboy · 01-27-2010, 08:20 PM

adjusting the TPS, what's the TPS and where is it?
I took off my 1996 TB and was looking it over and where the Throttle cable attaches to the lever that is spring loaded there is a black round knob with a screw end. what is that for? Is it something that will help in the adjusting it? Could someone tell me more about that?
Thanks

magboy · 02-08-2010, 02:23 PM

Now I put on another TB and the idle is a little low when warm, not bad. And a good idle at start up. I ran it for about 20 miles then the engine service soon lite came on. What would of caused that. I did replace the front small vacumme line as it had a small crack in the hose. I cleaned the TB prior. It was in a 96 geo and the lite was not on. Thanks for your help.