RPM's drop 600 when I start the truck

[Greg Jorczyk]

My 2003 Sport trac has 110,000 on it. When cold and I start the truck the RPM's go up to about 1500 for a second, then drop to around 600RPM for a second, then the truck almost wants to stall, then goes to a smooth idle at 1000RPM's. When the truck has been driven for a while I do not have the problem when I restart it.



I have replaced the fuel filter, spark plugs, pvc and air filter. Any suggestion what I might check as to why the RPM's drop to about 600 for a second when cold and truck almost wants to stall?



Thanks for the help



Greg

 

[swshawaii]

Clean the IAC first, followed by the throttle body, and MAF.

Never hurts to check the PCV elbow while you're in there.

 

[John G]

Agree to start with cleaning the Idle Air Control Valve.



A very common problem for a 1st generation truck that has trouble idling when cold. Costs pretty much nothing to clean it. In my case, the problem recurred after one year, and then more frequently after that, so I ended up replacing the IAC valve and that solved the idling problem more permanently.

 

[John G]

Agree to start with cleaning the Idle Air Control Valve.



A very common problem for a 1st generation truck that has trouble idling when cold. Costs pretty much nothing to clean it. In my case, the problem recurred after one year, and then more frequently after that, so I ended up replacing the IAC valve and that solved the idling problem more permanently.

 

[Greg Jorczyk]

I first cleaned the IAC which made it worse at startup, then cleaned the throttle body which was in pretty bad shape. It then started flawlessly and idles like it is brand new. Just one last question what is the MAF?



Again thanks for the help, it is greatly appreciated



Greg

 

[swshawaii]

The expensive Mass Air Flow sensor is very delicate and should be cleaned carefully.

I would NOT remove it from the housing, just use the long spray tube supplied.

Loosen the intake hose from the air box and check your filter while you're at it. GL



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