Pulsing Idle Disappears when Idle Air Control Valve is Disconnected

2knob · 04-16-2008, 08:46 PM

So what does that mean?

I rebuilt the motor recently, with Atkins 3mm parts, silicone vacuum, HKS downpipe, PFC, and a few new parts. It started the first time, and needed no adjustments. It's run perfectly until a few weeks ago, when I took it down to work on the upholstery, pulling the stock radio/CD in the process.

I start it, accelerated warm-up is fine, but when at temperature, it pulses between 800-1400 rpm. I swapped the Idle Air Control Valve, same problem. I adjust the TPS (narrow=1, full=.44), through the PFC, but no change. Electrical loads and air conditioning appear to have no effect on the problem.

I unplugged the Idle Air Control Valve and the problem, along with the accelerated warm-up, disappears. It idles (without A/C) and runs as good as ever.

So where does one go now? What inputs contribute to the IAC actions?

Thanks for any help...

04-16-2008, 08:46 PM	#1
2knob The Newbie Join Date: Feb 2008 Location: Bay Area, CA Posts: 18 Rep Power: 0	Pulsing Idle Disappears when Idle Air Control Valve is Disconnected So what does that mean? I rebuilt the motor recently, with Atkins 3mm parts, silicone vacuum, HKS downpipe, PFC, and a few new parts. It started the first time, and needed no adjustments. It's run perfectly until a few weeks ago, when I took it down to work on the upholstery, pulling the stock radio/CD in the process. I start it, accelerated warm-up is fine, but when at temperature, it pulses between 800-1400 rpm. I swapped the Idle Air Control Valve, same problem. I adjust the TPS (narrow=1, full=.44), through the PFC, but no change. Electrical loads and air conditioning appear to have no effect on the problem. I unplugged the Idle Air Control Valve and the problem, along with the accelerated warm-up, disappears. It idles (without A/C) and runs as good as ever. So where does one go now? What inputs contribute to the IAC actions? Thanks for any help...