Idle fluctuates

[valuvan2000]

Most of the time my 92 idles great but sometimes when it's cold it will idle so low it almost dies and sometimes when coming off of the throttle to a stop it will idle around 2000 rpm for several minutes. Any ideas?

 

[Tuna]

2 things come to mind - dirty throttle body and dirty injectors

I'd clean the throttle body first and pay close attention to the Idle Air Circuit.

 

[TedC]

Check the TPS. Monitor volatage from idle position to WOT back to idle. Voltage should increase or decrease smoothly. Analog voltage meter actually works better for this, but a DVOM will work as well. As stated above, throttle body and IAC should also be checked.

 

[valuvan2000]

Thank you, I'll try both of those.

 

[Stogie D]

afternoon all - I'm having a similar problem - when warm sitting at a light in neutral (6 speed) sometimes the idle will fluctuate up & down by 800 to 1000 rpm - sometimes it stays up between 1500/2000 rpm (sometimes it's just fine) - if I tap the gas pedal the idle drops right back to normal - on some days the service engine light comes on, on other days it does not - when it is on, if I turn the car off, then start it back up, the light is off - then it may or may not come back on - I dont have a code reader - any ideas - am reluctant to take it to Chevy as they are KILLIN me over there - this is my first FI 350 & have not had it long - Thanks, D.

 

[valuvan2000]

What I did was remove the throttle body and cleaned it with a toothbrush and some throttle body cleaner. I also replaced the idle air controller as the spring was broke. Put it back together with a new gasket and it's been fine. My wife said her toothbrush tastes funny for some reason, though.:L

 

[Schrade]

afternoon all - I'm having a similar problem - when warm sitting at a light in neutral (6 speed) sometimes the idle will fluctuate up & down by 800 to 1000 rpm - sometimes it stays up between 1500/2000 rpm (sometimes it's just fine) - if I tap the gas pedal the idle drops right back to normal - on some days the service engine light comes on, on other days it does not - when it is on, if I turn the car off, then start it back up, the light is off - then it may or may not come back on - I dont have a code reader - any ideas - am reluctant to take it to Chevy as they are KILLIN me over there - this is my first FI 350 & have not had it long - Thanks, D.

I think you have half a dozen code readers. Here's a couple of brand new ones with the protective insulation wrapper still on them.

1) Grab a pencil and paper.
2) Remove ALL insulation from code reader.
3) Insert into appropriate holes, turn key to 'ON' (not start), observe ALL codes readout on speedo.
4) Start writin'.
5) Post results in CAC forums, get repaired, and DRIVE!!!

 

[Schrade]

My wife said her toothbrush tastes funny for some reason, though.:L

I think she shouldn't knock it. Nothin' like a little carbon/tarter control toothpaste! :L