Fast Idle at Startup

[Doug H]

When my Sport Trac sits for a three or four days or more, and I start it, the engine races for the 1st few seconds. If I drive the Trac daily startup is normal. I'm wondering if an injector is leaking gas into the engine causing the fast idle at startup. Any thoughts?



Thanks

Doug in NC

 

[Rodger Tellefson]

Have you done this project?

 

[Doug H]

Yes, I've completed this project.

Thanks

Doug in NC

 

[EddieS'04]

I drive my trac daily. It has always raced to 1400rpm @ startup. In a few seconds it drops to 1000rpm. Then to 900rpm. As It gets to normal operating temp, it drops to 750rpm.

 

[Doug H]

I've had this truck since new in 2004 and it just started doing this. Maybe I'll go by autozone and see if there are any check codes stored in the computer.



Doug in NC

 

[scott degroot]

How long is a few seconds....3???

 

[Doug H]

Maybe 5 is reves up very fast then immediately drops to a normal idle. I'm concerned because the oil pressure isn't built up at that moment.



Thanks

Doug in NC

 

[scott degroot]

5 seconds @ 1400 rpm seems a bit much. An injector leaking would cause it to flood and start hard, not idle high. It's puzzling though that it only does this after sitting for a few days. If it just sits overnight is it ok? How's the battery?

 

[Kevin Palmer]

Could be a small vacuum leak. I think it would be worth plugging in with a reader to see what the temp sensor is saying the engine temp is BEFORE you start it, then look at it as soon as you start it.



Could be lazy/slow or simply defective but within range. If it is not accurate, it will tell the ECM one thing when it is really a different temp. Thus the IAC acting like it does until additional input gets to the ECM.

 

[Doug H]

Thanks for the replies.



When just sitting overnight, the starts are normal. Seems that it has to sit 3 or 4 days before the really fast idle at start will occur.



Doug in NC