Low RPM at start-up and at low gears.

[itamnala]

Hi Guys,

Appreciate if you could give me your inputs on why my truck has low RPM (about 500) at start-up and slowly goes up to 1000 after a while. I also noticed that when the truck is running and changes to low gears, the RPM goes down to 500 RPM and about to shutdown the engine.

It didnt give-up on me yet since I had to press the gas pedal everytime it occur. Hope you could enlighten me on this one.

Thanking you in advance.

 

[John_Rock]

I could be the IAC(Idle Air Control) valve.

 

[itamnala]

Thanks John, as I am away home now, i'd be glad if you could post a picture of this IAC valve and its location. Furthermore, can this be cleaned or a replacement is a must?

 

[John_Rock]

Here's a picture of mine on my Job 1 Sport Trac. It might be in a slightly different location on a Job 2 Sport Trac. You might have a Job 2 ST.

 

[John_Rock]

But, I have problems with my IAC valve on my 2000 Explorer Limited v8. When it gets colder out the IAC valve seems to get stuck and a good whack with a screw driver unsticks it.

 

[itamnala]

Yes John, I do have a 2002 Explorer ST. Your inputs are highly appreciated. Though I cant do anything now, I will revert to you with some updates when I get home.

 

[itamnala]

I also experienced hard starting of the truck, do you think the battery may also contribute on the problem? How about spark plugs? But as I've said, even if the truck is already in motion, the low RPM occurs in low gears.

 

[John_Rock]

I also experienced hard starting of the truck, do you think the battery may also contribute on the problem? How about spark plugs? But as I've said, even if the truck is already in motion, the low RPM occurs in low gears.

This too can be attributed to the IAC valve not doing it's job.

 

[ncranchero]

X2 what John says. An EGR valve sticking open or partially open can do this also. Do you have a check engine light?

 

[itamnala]

No, I dont have the "check engine light" on the dash. What does EGR stands for and its purpose? Thanks for helping in...

 

[ncranchero]

EGR=Exhaust Gas Recirculation You don't say how many miles are on the truck but the fact that you have no CEL may rule out the EGR. The CEL does light when you first turn the key on doesn't it? Replaced the fuel filter lately?

 

[itamnala]

Yes, the CEL does light when the key is turned but goes out the moment cranking starts. The truck has 64K miles on it. I have not replaced the fuel filter yet. Do you think the fuel filter needs to be replaced?

 

[ncranchero]

If you know it's never been changed then surely @ 64K it needs it. What really needs to be done is the fuel pressure checked to rule out a low pressure issue. That being said, it would probably starve at high RPMS from low fuel pressure. Remove & clean the IAC as first mentioned. Then proceed from there.

 

[itamnala]

Got my truck running back to normal. Followed all your advice and recommendations and it worked. Thank you guys!

 

[Clusterpup]

So what did you do exactly to get it running right??

 

[itamnala]

I just removed and cleaned the IAC. I plan to have the fuel filter replaced on its 65K maintenance.

Again, my thanks to the Mods.