2000 LS keeps Stalling??????

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strokin95

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Hey guys I need alittle help. My girlfriend owns a 2000 LS when she starts it up and puts it in a gear (drive or reverse) ,takes off from a stop light it stalls. It started as an occasional thing but now it almost everytime. I have replaced the fuel pump and filter no change. Her coils were replaced about a year ago. There are not and codes. I think it might be a vac. leak but not sure the best way to check that. This thing has been a pita since she got it. I love the way it drives and looks but its a pos.

Thanks in advance
Robert
 
sorry - didn't read this thread....

If the car can idle - then likely your vacuum is ok (should be between -18hg - 21hg of mercury or -9.5psi to -10.5psi at idle). At least your mechanical vacuum - gaskets, fittings, ...etc are ok.

I'm thinking if it idles but stall as soon as you try to move - it's the IAC valve. So the little motor in the IAC is not adjusting and staying open. So it stay open (like at idle) and when you put the engine under slight load, or a little gas the IAC is not closing - so more air is coming into the intake than what is going through the throttle (bypassing by going through the IAC) and therefore stalling the car.

The pre-03 LSes use a weird IAC vavle that not only leaks air past the Throttle plate on idle but also feeds air to the fuel injectors to better atomize the fuel.


Check the IAC valve.
 
Ok I took the iac off it had a bit of carbon build up on it I cleaned it put it back on and it didnt stall untill just a bit ago. When you look at the valve when its ogg should it be closed or open? It looked as if it was about half and half.
 
With the IAC valve disconnected seasure IAC valve resistance - it should be between 6.0 and 13.0 ohms - if not - swap it.

Then check it of a short by measuring the resistance from either IAC valve pin to IAC valve case. if the resistance is less than 10,000 ohms - swap it.
 
Key on, engine off - measure voltage on IAC circuit between PCM harness connector pin and battery negative post. If voltage is not less than 1.0 volt - then you may have a short somewhere....

Measure resistance between IAC and PWR GND circuits at the PCM harness connector. If each resistance is not greater than 10,000 ohms - then you may have a short somewhere....

the other step needs a scan tool to read the IAC duty cycle:
- Reconnect IAC valve. Key on, engine running. With engine at normal operating temperature, accessories OFF and at closed throttle, the IAC duty cycle must be between approximately 22 percent and 45 percent.
Slowly increase engine speed to 3000 rpm and return to closed throttle.

If the IAC duty cycle within specification at closed throttle or the duty cycle does not respond to the change in rpm -swap the valve
 
Quik LS said:
Key on, engine off - measure voltage on IAC circuit between PCM harness connector pin and battery negative post. If voltage is not less than 1.0 volt - then you may have a short somewhere....

Measure resistance between IAC and PWR GND circuits at the PCM harness connector. If each resistance is not greater than 10,000 ohms - then you may have a short somewhere....

the other step needs a scan tool to read the IAC duty cycle:
- Reconnect IAC valve. Key on, engine running. With engine at normal operating temperature, accessories OFF and at closed throttle, the IAC duty cycle must be between approximately 22 percent and 45 percent.
Slowly increase engine speed to 3000 rpm and return to closed throttle.

If the IAC duty cycle within specification at closed throttle or the duty cycle does not respond to the change in rpm -swap the valve
Click to expand...

How much is this valve. I am starting to have a hesitation problem also, but no codes have been thrown.
 
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