Has anyone had issues with an aftermarket IAC valve???

I'm stumped....I'm sure some of you have seen my threads regarding my idle problem.

Still having the same issue...high idle at cold start and between gear changes until I shut off the engine and restart. I've cleaned the throttle body, installed new TPS sensor, and replaced the IAC twice with aftermarket part from local part store.

The idle was worse with new IAC, would not idle at all. The truck idle would bounce back and fourth and then stall with either of the new IACs. Ended up putting the old (OEM Ford) IAC back on and idle went back to idling high until restart. After restart Idle is great no problems. I can drive all day and not have idle problems unless I let the truck get cold. If I let it get cold I have to do the restart reprocess again and the idle is fine.

I would agree with some that say this is vacum leak, but I would think if it were a vacum leak it would still have the high idle after restart.

 

What brand is the IAC? The only aftermarket one I would get is BWD. Its made here not overseas.

Maybe your truck has a vacuum leak.

 

Both of the iac valves I got were bwd. You think it would be a vac. leak even though the idle problem stops upon restart? If it were a vacuum leak wouldnt it have high idle all the time?

 

Basically you restart it after it's warm the idle will be fine.

 

A hunting idle is typically caused by a sticky/faulty IAC and/or a vacuum leak. If the idle speed goes back to normal after a cycle of the key switch it's something electronic, typically the TPS. Was the TPS replaced? Was it an aftermarket? Have you measured it with a DVM?

 

Yes, tps was replaced with aftermarket part from autozone. No, I've no tested the dvm. Is the dvm adjustable on an 89?

 

Ford Fuel Injection » Throttle Position Sensor (TPS) Here is how to check and set the TPS. DVM is Digital Volt Meter which can be used to check the voltages at the TPS.

 

Good information....if I'm reading the info correctly. Turning the mounting screws is what adjusts the tps sensor? Is that right?

 

Some TPS sensors have slotted holes in them which enables them to be adjusted. Loosening the mounting the screws then turn the sensor. There is very little adjustment required. As long as the closed throttle voltage is between 0.6 to 1.00 VDC you are good. Then use that Digital Volt Meter to measure the voltage as the throttle is slowly opened to full throttle. Do it a few times, watch the output signal closely for signs of dips or spikes.

Great info in this thread from another forum: Ultimate Throttle Position Sensor (TPS) Thread - FSB Forums