Erratic RPM's when in neutral and or Park

[Jose Ayala]

When I took my ST to Ford to check the O/D drivelight blinking, I told them I had some erratic RPM's when ST was on Park or neutral.



This is what is happening, any time I sit on park or neutral, you can here RPM's going up for a couple of seconds and then it come back to normal. This does not happens when in drive or reverse, during these two modes the RPM's are within range and nothing demonstrates something wrong.



When Ford checked, they said nothing was wrong but I think I have a sensor bad or a hose damaged. No code is coming from check engine light.



Any one have had this issue before?



Jose

 

[Scott Heckler]

I would check the IAC and make sure it is clean. Then I would check for a vacuum leak.

 

[Todd Z]

Does the AC compressor kick on when it goes up ????



Todd Z

 

[Jose Ayala]

Todd,



no, A/C is not running at all times, so it happens even when A/C is not on. When compressor is on, I have not seen anything demonstrating something is wrong.



Jose

 

[Todd Z]

But does the compressor come on when the rpms go up, Even if you have the switch off ???



If not then it sounds like the IAC may need a cleaning..





Todd Z

 

[Jose Ayala]

no Todd, compressor is not coming on, so i will clean IAC and see what happens, thanks,



Jose

 

[Paul H]

I had the same problem at my 70,000 overhaul and they changed out the DPFE sensor.

It had very erratic RPM's like almost stalling and then catch itself

Paul H

 

[eric huskey 2]

I had this problem before and it was the intake gasket.

 

[Kevin Palmer]

Jose, in the case of the Trac, the A/C clutch kicks in and out often. It only does NOT in two positions. For example, if you have the defrost on, no matter the temp set, the clutch will kick in often...



This is what Todd is asking, not so much as if you have the A/c on.



I am with the others though, at least clean the IAC as it will only help, it can not hurt...

 

[Jose Ayala]

Coastiejoe,



I will clean IAC and I drove it this morning to work and when in drive gear, everything looks normal, just a litle high for me on the RPM side, it is running around 1k when brake is depressed, and i use to see her down between 750 and or 650, even with AC running.



if not changes are visible after, I will take it back to Ford.



Jose

 

[Todd Z]

I wounder if ford flashed the computer ??? I know you have the xcal, BUT ford may have raised the idle to take away the stalling...



Todd Z

 

[Jose Ayala]

Good question Todd, but no, I re-flashed the ST back to original settings before I took it to them. I re-flashed last night to my custom setting.

 

[Todd Z]

the truck could have been still learning since they disconnect the battery to repair the tranny...



Todd Z

 

[Jose Ayala]

Should i wait for a week before I do something?

 

[MARK CASTANEDA]

i have just gotten my truck out of the shop for a reason like yours. my st o/d light was flashing due to a tranny slip. i had to get my whole tranny overhauled. good thing the warranty covered it . maybe it could be that. dunno. well g/l trying to find out what it is. Marco Castaneda