Idle position
#1
09-30-2011, 07:15 PM
Idle position
Ok, Ive been messing with the camaro and I have it where I can fire it up and it idles at 900-1000 rpms. I can drive it around get it warmed up and the idle goes to 1700-2000. if I let it set there and idle for a few min it will finally come back down, but takes a while. Would that be a faulty Idle sensor?
Oh no engine light. Runs great tho.
Oh no engine light. Runs great tho.
#2
09-30-2011, 08:47 PM
I think what you are referring to is the Idle Air Control (IAC) valve. The PCM controls the idle speed by opening and closing the valve. If the throttle valve does not close fully, or if there are vacuum leaks, or if the IAC valve is dirty or malfunctioning, the PCM will have problems controlling the idle speed. There is also a throttle position sensor (TPS). This sensor tells the PCM the position of the throttle blades, and the PCM makes fast adjustments to the injector pulse width. Basically, the other sensors are not fast enough to keep up with the speed of the throttle valve motion, so the TPS gives the PCM a heads up on what to expect. If you are familiar with carbs, TPS function is similar to the function of the accelerator pump,except that it works both ways, closing and opening of the throttle valve. Generally, if the TPS is bad, the engine will have problem with stumbling when you stab the gas pedal.
Last edited by z28pete; 09-30-2011 at 09:03 PM.
#3
09-30-2011, 09:15 PM
I think what you are referring to is the Idle Air Control (IAC) valve. The PCM controls the idle speed by opening and closing the valve. If the throttle valve does not close fully, or if there are vacuum leaks, or if the IAC valve is dirty or malfunctioning, the PCM will have problems controlling the idle speed. There is also a throttle position sensor (TPS). This sensor tells the PCM the position of the throttle blades, and the PCM makes fast adjustments to the injector pulse width. Basically, the other sensors are not fast enough to keep up with the speed of the throttle valve motion, so the TPS gives the PCM a heads up on what to expect. If you are familiar with carbs, TPS function is similar to the function of the accelerator pump,except that it works both ways, closing and opening of the throttle valve. Generally, if the TPS is bad, the engine will have problem with stumbling when you stab the gas pedal.
#4
09-30-2011, 09:51 PM
Yes, and also make sure the throttle valve itself is closing all the way without sticking. No air should go through the throttle valve when it is closed, all idle air should go through the IAC only.
#5
09-30-2011, 10:25 PM
I can't remember if it was on this forum or another, but I was told that the TB blades should NOT close all the way...? Was told they need to be opened ever so slightly and not fully closed. I had to do a lot of work on my TB to slowly smooth out the inside because my blades were ALWAYS sticking it seemed like. Now it doesn't stick but I was still told not to have them fully closed....so now I've seen two contradicting pieces of info. Can you clear it up?
#6
09-30-2011, 10:47 PM
If you read the FSM, it shows that a rubber like coating is applied to the inside of the TB to ensure a complete seal and to prevent sticking. Cleaning of the TB with materials that remove the coating damaged the TB. The TB stops are set at the factory so that the TB closes fully without going through the coating, and should not be adjusted.
#10
10-01-2011, 05:16 PM
IDK if that is just poor sound quality in the video, but it sounds like it's real rough or there is a lot of vibration noise in the video. I've also read/been told that with modifications like heads, headers, both intake and tb ported, and a cam that it will run a little higher in the 1000rpm range...idk if it is normal or just accepted.