94 3.0 Rev up to high after replacement of IAC Valve

[technikant]

Hi everybody,
I am the owner of one of the three remaining 94 Ranger splash 3.0L in Germany. Due to preventing Maintenance I have replaced the idle air control valve. Since that day the engine revs up much to high (about 3000 RPM) at cold start (about 40°F). RPM drop then slowly to high idle for cold engine. Question :
- bad aftermarket IAC?
- Missing any signal for the ECM? Coolant temperature sensor was replaced month ago already.
Any ideas?
Greetings from Germany
Dieter

 

[Uncle Gump]

Welcome to TRS...

From the Good old USA

My first thought... non of the engine sensors should be changed as preventative maintenance. Exception would be O2 sensors... as they have life span.

My suggestion would be to put the IAC back on and see if it changes back to a better place. I hope you didn't toss it in the garbage.

Many of the replacement parts on the market these days are just rubbish.

 

[technikant]

Thanks for the advice.
Yes, I still have the old one. This engine is 30 years old now and has 178 k miles on the odo. My thinking was to do it some good now because more and more parts are disappearing from the market. I read an article somewhere, that old IAC's can get stuck and fry your ECM because of overcurrent. That's the reason why I did it.
And yes, both O2 sensors I replaced last year already because of lack of performance.