Engine Start Transient

[ssfrebo]

I don't like the way my 99 4.0 SOHC starts...it shoots up to almost 2000 RPM when cold before it quickly returns to normal idle, and is not quite so bad when hot. Is there anyway or anything to adjust to limit the RPM startup transient? I guess I was spoiled by my previous vehicle, a 96 Blazer, which just started like a normal engine. My gut feeling is that this is a computer controlled thing, but I'm asking the forum anyway just in case there is a way.......

PS: Just bought this vehicle a few weeks ago. I had not owned a Ford since 1991 when we bought a new silver and black explorer.

 

[TPLYNCH]

That's normal for the engine. Ford's way of getting oil to the top of the engine as quickly as possible....

 

[Opera House]

If it really bothers you

I heard of a guy that was having noises from his IAC. He removed it and cut a gasket for it that had the air holes 1/3 the size of the ones on the IAC. He said this got rid of his noise. Always thought that was quite creative. That same method would also limit the top speed at idle. Might make starting mixture initially a tad richer. Don't see a problem there. Sounds like a good science experiment. Why don't you try it and tell us how it works. A resistor in series with the IAC might also work. My guess is about 3.9 ohms @ 1 watt for a first try.

 

[ssfrebo]

I think its worth a try, I always enjoy a little experimenting....