Causes for slight rpm surges in park/neutral/drive while sitting

[rwh963]

2007 v6 w/255k. been noticing this for a couple of years. don't notice anything driving. rpm's bump up from about 800 to about 1100 while sitting. any ideas why?

 

[Hungryhawk]

In former vehicles that was a sign of IAC valve getting a carbon build up inside it or Throttle Body. Does your truck have an Intake Air Control Valve?
I use a bottle of Techron in gas tank every oil change to stay ahead of carbon build up.

 

[riceandpho]

i just changed my pcv valve on the 4.0 v6, not sure if that is also a cause. i did the vent hose too, also have you kept up with your maintenance? spark plugs? i have 238200ish miles.

Part No.: 12261-31030
HOSE, VENTILATION, N
Replaced by: 12261-0P010

Part No.: 12204-31030
VALVE SUB-ASSY, VENT

 

[sundance21]

AC cycling off and on.

The 4th gen has a harsher step up than the 5th gen. AC will cycle on and off if you have it in Auto climate setting unless you click the AC button to turn it off.

That is the only thing I know that would cause a 300 rpm swing. My penny.

 

[Schmutz]

In former vehicles that was a sign of IAC valve getting a carbon build up inside it or Throttle Body. Does your truck have an Intake Air Control Valve?
I use a bottle of Techron in gas tank every oil change to stay ahead of carbon build up.

We had the idle surging problem with my sons 1st gen v6 3.0. I realize this is the 4th gen thread, but is it possible that your comment equally applies? Thanks

 

[rwh963]

thx for the replies. AC is off, so that should not be an issue. at 255k now. plugs replaced at 200k. throttle body and MAF in April 2022 at about 230k.

 

[Moist]

2007 v6 w/255k. been noticing this for a couple of years. don't notice anything driving. rpm's bump up from about 800 to about 1100 while sitting. any ideas why?

The V8 Does this too. I've got a non-TTVI v8.
I had always thought it just did that to warm the engine up. I've noticed it doesn't do it on a hot engine. It also might do it to calibrate to new fuel but I'm not sure.
My A/C line ruptured and it no longer engages at all, so I think it's the ECU making it do it. Thats my 2 cents at least.

 

[riceandpho]

try to change out the pcv valve, its less than 10 bucks to do on your own. i was squeezing the hose and had a similar effect.

 

[rwh963]

my engine air filter is dirty. changed it. that might be the issue (gasping for air!).

 

[rwh963]

my engine air filter is dirty. changed it. that might be the issue (gasping for air!). also put in a new cabin filter.